Wiadomości Chemiczne

Wiadomości Chemiczne, 2008, Vol.62

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  1. The 80th Birthday Anniversary of Professor Lucjan Sobczyk
    Aleksander Koll

  2. Magneto-Structural Correlations for the Molecular Systems of Cu-Picolinate and Cu-Quinaldinate
    Bogumiła Żurowska

  3. Synthesis of Amphiphilic Graft Copolymers VIA Controlled Radical (Co)Polymerization of Hydrophilic Poly(Ethylene Oxide) Macromonomer
    Dorota Neugebauer

  4. Dissociation and Association Effects in Proton Transfer Reactions Between C-Acids and Organic Bases in Aprotic Solvents
    Iwona Nowak, Iwona Binkowska, Małgorzata Stańczyk-Dunaj, Arnold Jarczewski

  5. Chemical Forms of Selected Elements in Plants, Medicinal Plant Raw Materials and Plant Extracts
    Paweł Konieczyński

  6. Chemical Characterization of an Unknown Resinous Material Found in Coal Seams
    Wiesław Z. Antkowiak

  7. Okruchy. "Bełkotka"
    Ignacy Z. Siemion

  8. The 40th Anniversary of the Faculty of Chemical Technoligy of Poznań University of Technology
    Zenon Łukaszewski

  9. The Synthesis of Corroles
    Beata Koszarna, Daniel T. Gryko

  10. Electronic Interactions in Binuclear Molybdenum Nitrosyl Complexes
    Andrzej Włodarczyk, Piotr Romańczyk

  11. Ti(Iv) and Zr(Iv) Alkoxo Complexes Wwith O-Donor Ligands.
    Synthesis, Structural Characterization and Applications
    Piotr Piszczek

  12. Redox-Active Receptors of Cations and Anions
    Katarzyna Zięba, Joanna Taraszewska

  13. Toward a Better Understanding of Phosphoryl Transfer Reaction: The Use of Phosphoroorganic Biocides in Research Studies
    Witold Przychodzeń

  14. Non-Nucleoside Reverse Transcriptase Inhibitors of HIV
    Andrzej Orzeszko

  15. Okrychy. O ogniu greckim i prochu strzelniczym. Wypisy z lektur przygodnych
    Ignacy Z. Siemion

  16. Porphyrin Derivatives with an Acetylene Moiety
    Anna Berlicka, Lechosław Latos-Grażyński

  17. Mesoporous Carbons: Synthesis and Properties
    Jerzy Choma, Mieczysław Jaroniec, Aleksandra Zawiślak

  18. Models of Activated Carbons: Past, the Present and Future
    Piotr A. Gauden, Artur P. Terzyk, Sylwester Furmaniak

  19. Magnetic Interactions through Hydrogen Bonds
    Maria Korabik

  20. Polyyne Compounds and Complexes. Synthetic Strategy and Applications
    Karolina Osowska, Sławomir Szafert

  21. New Antileprosy Drugs
    Krystyna Nowak, Piotr Suryło

  22. Death of the Beautiful Theory Which Says that Carbon Dioxide Governs the Earth Climate
    Przemysław Mastalerz

  23. Okruchy. O ogniu czyśćcowym
    Ignacy Z. Siemion

  24. Chemical Solid-Phase Synthesis of Oligonucleotides. Possibilities and Limitations of Solid-Phase Supports
    Izabela Burzyńska-Pędziwiatr, Lucyna Woźniak

  25. Profile of Statherin - Salivary Protein Involved in Homeostasis in Oral Cavity
    Dominika Jackiewicz-Barańska, Elżbieta Kamysz, Zbigniew Maćkiewicz

  26. MACROCYCLIC COMPLEXES OF RADIONUCLIDES IN NUCLEAR
    Agnieszka Majkowska, Aleksander Bilewicz

  27. Catalytic Activity of Single Enzyme Molecules
    Jolanta Jakubaszek, Andrzej Molski

  28. New Methods of Ultramarine Pigments Synthesis from Zeolites
    Aldona Jankowska, Stanisław Kowalak

  29. Pd-Ag, Pd-Pt, Pd-Au, Pt-Ag, and Pt-Au Bimetallic Systems as Heterogeneous Catalysts of Reactions with Hydrogen
    Piotr Matczak

  30. Determination of the Absolute Configuration by Nuclear Magnetic Resonance
    Renata Kołodziejska, Lidia Jasińska, Aleksandra Karczmarska, Marcin Dramiński

  31. Chromatographic Methods of Air Pollution Analysis at the Communal Management Facilities
    Anna Sadowska-Rociek, Magdalena Kurdziel

  32. Okruchy. VI. Wynalazcy z Nieospolitej Rodziny
    Ignacy Z. Siemion

  33. Application of Desilylative Coupling of Vinylsilanes and Ethynylsilanes in Sequential Reactions in Organic Synthesis
    Wiesław Prukała

  34. Development of the Porous Structure of Active Carbons Obtained by Physical and Chemical Activation of Fossil Coals
    Piotr Nowicki, Helena Wachowska

  35. Anionic Polymerization with Electron-Transfer Reagents
    Zbigniew Grobelny, Andrzej Stolarzewicz, Marcin Szczepański, Beata Piekarnik

  36. Magnesium Compounds with Aryloxo Ligands - Initiators of Lactide Polymerization
    Jolanta Ejfler

  37. Chemistry and Biological Activity of Garlic (ALLIUM SATIVUM)
    Halina Kwiecień

  38. Okruchy. VII. O "Manifeście Pana Aspiryny", "Kwasie Argininobursztynowym" i "Jonizacji".
    Inspiracje chemiczne w sztuce współczesnej

    Ignacy Z. Siemion

  39. Prof. dr. hab. inż. Józef J. Ziółkowski, Dr.H.C. Mult, (1934-2008)- An Obituary
    Anna Maria Trzeciak

  40. Bridged Polysilsesquioxanes - Synthesis, Structure and Adsorption Properties
    Mariusz Barczak, Andrzej Dąbrowski

  41. Modified Active Carbons - Preparation and Prospective Application
    Piotr Nowicki, Helena Wachowska

  42. Contemporary and Prospective Explosives
    Stanisław Cudziło

  43. Combretastatin A-4 (Ca-4) and its Analogues. Synthesis and Biological Activity
    Krystyna Dzierzbicka, Paweł Kubacka, Seweryna Renusz, Aleksander M. Kołodziejczyk

  44. Role of Hipoxia in Advances in New Anticancer Diagnostics and Therapy
    Katarzyna Błaszczak-Świątkiewicz, Elżbieta Mikiciuk-Olasik

  45. Peptide-Oligonucleotide Conjugates: Synthesis And Applications
    Renata Kaczmarek, Ewa Radzikowska, Janina Baraniak

  46. Okruchy VIII. Chemia a polityka
    Ignacy Z. Siemion

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THE 80TH BIRTHDAY ANNIVERSARY OF PROFESSOR LUCJAN SOBCZYK

Aleksander Koll

Wydział Chemii, Uniwersytet Wrocławski, ul. F.Joliot-Curie 14, 50-383 Wrocław



Wiadomości Chemiczne, 2008, 62, 1.
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MAGNETO-STRUCTURAL CORRELATIONS FOR THE MOLECULAR SYSTEMS OF Cu-PICOLINATE
AND Cu-QUINALDINATE

Bogumiła Żurowska

Wydział Chemii Uniwersytetu Wrocławskiego, ul. F. Joliot-Curie 14, 50-383 Wrocław


This article concerns information on a synthesis, and structural and magnetic characterization of copper(II) compounds based on two classes of carboxylate ligands containing heterocyclic nitrogen atom of pyridine and quinoline i.e. pyridylo-2-carboxylate (2-picolinate, 2-pic) and quinolilo-2-carboxylate (2-chinaldynate, 2-qic), (Fig. 1, Tab. 1). Such compounds are products of a direct reaction of picolinate or chinaldynate acids with copper(II) salts [19, 37, 45, 48, 50, 51] and the hydrolytic [20, 52] and non hydrolytic [53] decomposition of ligands. Picolinate ion forms compounds of the general formula Cu(2-pic)2·2H2O (1) or [Cu(2-pic)2Br2][(2-picH)2] (2). The compound of the formula Cu(pyridylo-2-carboxylate)2 exists in three polymorphic forms: monomeric (Cu(N2O2) chromophore) (3), and two (4 and 5) polymeric (1D) (Cu(N2O4) chromophore). With halide ions isostructural polymeric (2D) compounds of the formula Cu(2-pic)X, X= Cl (6) or Br (10) are formed (Cu(N2O2X) chromophore). However, with chinaldynate ion exist compounds of the stoichiometries: two isomeric forms of Cu(2-qic)2·H2O (7 and 8), which involve the same CuN2O3 chromophore (distortion isomers), and Cu(2-qic)X, X = Cl (9) and Br (11) compounds. The chloride and bromide (9 and 11) polymeric (2D) Cu(2-qic)X compounds, which crystal structure consists of two different chromophore Cu(N2O2X) and Cu(O2X2) are isostructural. Crystal structure of these copper-picolinate and copper-quinaldinate systems indicate, that carboxylate group in both ligands offers a variety of coordination modes leading to the formation of mononuclear and polynuclear compounds. The monomeric form of Cu(2-pic)2 (3) is an example of a square-planar copper(II) compound in which structure is achieved by important π-π stacking intermolecular interaction. This interaction leads to antiferromagnetic coupling (J = -0.76 cm-1) [129]. The polymeric compounds of the formula Cu(2-pic)2 (4 and 5) are an example of an out-of-plane double carboxylato-bridged copper(II) compound resulting in the formation of an infinite chain. The magnetic properties revealed a weak intrachain antiferromagnetic coupling in both compounds (J = -0.73 and -1.04 cm-1 for 4 [48] and 5 [49], respectively). The structures of Cu(2-pic)X (6 and 10) and Cu(2-qic)X (9 and 11) compounds are based on syn-anti carboxylate bridge and additionally on halido-bridge. The carboxylate bridges transmit a weak ferromagnetic exchange (J < 0.5 cm-1) in both compounds [46, 47, 50]. For Cu(2-pic)X observed ferromagnetic coupling through dichloro-bridge (J = 15 cm-1) [46] is stronger than that through dibromo-bridge in bromide analog (J = 8.31 cm-1) [50]. For Cu(2-qic)X observed strong antiferromagnetic coupling through the single chloro-bridge (J = -57 cm-1) [47] is much weaker than that transmitted by the single bromo-bridge (J = -102.5 cm-1) [50]. The magnitude of the magnetic coupling through the non-covalent interactions (hydrogen bonds and π-π stacking) is also discussed on the basis of the structural data [48, 49, 129, 130]. The magnitude of the exchange interactions between copper(II) ions are discussed on the basis of the molecular and crystal structures, in terms of bond properties and known theory of exchange [62-65, 100-104].
 
Keywords: copper(II), carboxylate ligands, halide ligands, structure, magnetism


Wiadomości Chemiczne, 2008, 62, 9.
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SYNTHESIS OF AMPHIPHILIC GRAFT COPOLYMERS VIA CONTROLLED RADICAL (CO)POLYMERIZATION OF HYDROPHILIC POLY(ETHYLENE OXIDE) MACROMONOMER

Dorota Neugebauer

Instytut Nauki o Materiałach, Uniwersytet Śląski, ul. Bankowa 14, 40-007 Katowice


A combination of hydrophilic and hydrophobic characters in one macromolecule of a polymer provides amphiphilic behavior [1, 2]. Such unique properties, which have found significant interest, are exhibited by graft copolymers containing poly(ethylene oxide) (PEO) as side chains attached to the backbone (Scheme 1) [20]. They have greatly expanded a class of materials important for science and biomedicine. This review article describes the PEO graft copolymers prepared by a variety of synthetic procedures used for the atom transfer radical (co)polymerization (ATRP) (Scheme 2) [15-17], i.e. directly by the grafting through, which is also named as the macromonomer method or by the grafting from technique, which requires the use of a multifunctional macroinitiator.

Densely homografted copolymers also called molecular brushes [21-25] were obtained by homopolymerization of PEO macromonomer (Scheme 3). The density of PEO grafts was decreased in the copolymerization of PEO macromonomer with a low molecular weight comonomer resulting in loosely grafted copolymers contai-ning uniform PEO side chains (Scheme 4) [46-48]. Consequently, the copolymerization of two macromonomers yielded heterografted brushes (Scheme 5) [21, 23, 26, 45, 53-57]. In this case, the composition of copolymers was designed by the selection of proper comonomers with comparable (rM1 = rM2/rM1 ~ rM2) or different (rM1 > rM2, rM1 < rM2) reactivity ratios, which can form alternating/ random copolymers or spontaneous gradient of PEO chains along backbone, respectively. Using monofunctional macroinitiators with comb or linear composition for polymerization of PEO macromonomer resulted in comb-comb [31] or semi-comb diblock copolymers [21, 23, 27-30]. The reverse structures were also obtained, when the PEO graft copolymers were applied as the monofunctional macroinitiators [31, 32].

The use of polymeric multifunctional macroinitiators (graft or linear) in the polymerization of monomer or macromonomer led to the heterografted copolymers (Scheme 4) [32, 50, 51] or more complexed double grafted copolymers (Scheme 3) [25].

The applications of the PEO graft copolymers in numerous fields are also presented to show their versatile potential [25, 26, 46, 53, 55, 56, 68-76].
 
Keywords: graft copolymers, amphiphilicity, PEO, ATRP


Wiadomości Chemiczne, 2008, 62, 49.
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DISSOCIATION AND ASSOCIATION EFFECTS IN PROTON TRANSFER REACTIONS BETWEEN C-ACIDS AND ORGANIC BASES IN APROTIC SOLVENTS

Iwona Nowak, Iwona Binkowska, Małgorzata Stańczyk-Dunaj, Arnold Jarczewski

Zakład Chemii Ogólnej, Wydział Chemii, Uniwersytet im A.Mickiewicza
ul. Grunwaldzka 6, 60-780 Poznań


The proton transfer reactions in solutions have attracted the attention of a number of laboratories for many years. These processes seem to be quite simple as they proceed without perturbation of bounding electrons and have low steric demands what enables study of their mechanism. However, many factors influences the mechanisms of these reactions. Among them and not the trifling ones, are dissociation-association effects accompanying them.

The definition, behavior and reactivity of carbon acids (C-acids) depending on the type of electron withdrawing group are given [1-57]. Also the values of dissociation constants of C-acids in protic and aprotic solvents are collated in Tables 4, 5 and 7 [11, 38, 49].

The nature of products, free ions and ion pairs, of proton transfer reactions of various C-acids and strong organic bases are carefully discussed. Also their spectral characteristics are given. The equilibria and the possible routes between the substrates and the products of these reactions are also shown [58-66].

The reasons of the homoconjugation effects as a result of an association of the ionic products of the proton transfer reactions in different solvents are discussed in the context of their solvation abilities [67-86].

The formation constants of the homoconjugation complexes of amidine and guanidine bases in relation to their pKα values are quoted in Table 6 [87-95].

The nature of heteroconjugation complexes formed as the result of hydrogen bonding of different entities in the system of proton transfer reactions is discussed [96-116].

The pKα values of a number of C-acids, derivatives of nitromethane, measured in acetonitrile by potentiometric method, are given in Table 7. The pKα values of these derivatives measured in DMSO/H2O systems are compared with those obtained in acetonitrile [18, 38]. The general view of these problems is discussed and carefully reviewed.
 
Keywords: proton transfer, C-acids, strong organic bases, dissociation, association, homo and heteroconjugation constants


Wiadomości Chemiczne, 2008, 62, 67.
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CHEMICAL FORMS OF SELECTED ELEMENTS IN PLANTS, MEDICINAL PLANT RAW MATERIALS AND PLANT EXTRACTS

Paweł Konieczyński

Wydział Farmaceutyczny, Akademia Medyczna w Gdańsku, Al. Gen. J. Hallera 107, 80-416 Gdańsk


In this article, the chemical forms of selected essential elements - non-metals and metals - in plants, medicinal plant raw materials and plant extracts, are discussed. The introduction contains the description of basic terms used within the text, such as speciation, speciation analysis, hyphenated techniques, as well as provides the information on the reason of the studies on the chemical forms of selected elements [1-5].

In the Chapters 1, 2 and 3, the characterization of three essential non-metallic elements - nitrogen, phosphorus and sulphur, is presented. The importance of non-metals for life, especially their involvement in ATP, ADP, nucleic acids, proteins, phospholipides and sulpholipides, is highlighted. From the analyzed chemical forms of nitrogen, the most important from the point of speciation analysis, are nitrite and nitrate form of this element. Within the Chapter 1, the studies on the former are reviewed, with the accent on their analysis (Table 1) in medicinal plant raw materials and in herbal drugs [29-35]. Chapter 2 describes the investigation on chemical forms of phosphorus, from them the most important - inorganic phosphate phosphorus [38-41, 46]. The chemical forms of nitrogen and phosphorus are related also to the indexes of ADI and RDA, to give the knowledge on their potential impact on human's health. Chapter 3 is focussed on sulphur and its chemical forms - inorganic and organic sulphur in plant material [53, 54]. Special attention to potentially dangerous for human chemical form of sulphur - SO2 in several Chinese herbs [59] is paid on.

Chapter 4 concerns the analysis of chemical forms of iron, selected as characteristic example of an essential metallic elements, and is based on the studies of Fe and other metals concentration in crude drugs as well as in infusions, decoctions and herbal teas (Table 2), providing also evaluation of the extraction efficacy of iron with the comparison with the other important elements [65, 66].

In the Chapter 5, the examples of speciation studies of other metals (Mn, Zn, Mg, Pt and other) are discussed [82-101]. The analytical methodology, including speciation scheme for selected metals, especially in plant materials used in medicine, is given. Hyphe-nated techniques, such as HPLC with combination of different detection techniques (spectroscopic, electrochemical) applied for the speciation analysis of metals in plant material, are reviewed.

The Summary contains the final remarks and conclusions on the described examples of speciation studies of nitrogen, phosphorus, sulphur, iron and other selected metallic elements important for life, as well as perspectives for the further development of analysis of their chemical forms in the future.
 
Keywords: Chemical forms of N, P, S and Fe, speciation analysis, plant material, medicinal plant raw materials, herbal drugs


Wiadomości Chemiczne, 2008, 62, 97.
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CHEMICAL CHARACTERIZATION OF AN UNKNOWN RESINOUS MATERIAL FOUND IN COAL SEAMS

Wiesław Z. Antkowiak

Wydział Chemii, Uniwersytet im. Adama Mickiewicza, ul. Grunwaldzka 6, 60-780 Poznań


An inhomogeneous resinous material of a yellow to tea-like colour and of an elastic to hard consistency was found as a thin layer inserted between coal seams. An explanation of its origin and chemical composition is now being of particular interest to geologists. The resin was found to be composed of carbon, hydrogen, nitrogen and, by assumption, oxygen. The radiocarbon dating measurement carried out on the raw resin gave a value of 8490 ± 50 years BP and an explanation of this result is suggested. Only about one third of the raw resin was soluble in organic solvents at temperatures below 100°C. The etched insoluble amorphous residue that stays solid up to 260°C and reveals carbonyl absorption in IR, when subjected to transesterification in methanol at reflux in the presence of sodium methoxide yielded quantitatively a soluble in chloroform product, which shows an optical activity and proved to be a difficult to separate mixture of methyl esters and alcoholic moiety. The etching of the raw resin with hot water gave an optically inactive mixture of double homologues of poly(oxyethylene)-poly(oxypropylene) glycol structure, that differ one from the other in a number of methylene and oxyethylene groups. The product revealed a characteristic ESI-MS spectrum, the pattern of which could be seen in almost every fraction obtained by extraction of the raw resin with different organic solvents or its transesterification product mixture. The physical properties, other than ESI-MS, showed in the resinous material the presence of some additional components different from polyethylene-polypropylene glycol homologues. The polyurethane character of the resin was demonstrated by identification of bis(4-isocyanatophenyl)methane in the chloroform extract of the raw resin as a secondary product formed in the thermal conditions of GC-MS, and of bis[4-(methoxycarbonylamino)phenyl]methane which occurred in the transesterification product mixture. Additionally, the presence of methyl 9-octadecenoate, accompanied by methyl esters of other fatty acids, was also determined. Finally, after several repeated column and plate chromatographic separations, two "homogeneous" substances of [α]D = +25.7° and +20.2°, respectively, the main components responsible for the optical activity of most resinous fractions, were isolated from the transesterification product mixture. The principal products of these "chromatographically pure" substances turned out to have the adduct structure of methyl ricinoleate and bis(4-isocyanatophenyl)methane. It was proved that in the case of a compound revealing the higher specific rotation, two molecules of methyl ricinoleate were bound, using their OH functions, to one molecule of diisocyanate, giving bis[4-(1-methoxy-1-oxo-9-octadecen-12-yloxycarbonylamino)phenyl]methane. The molecular structure of a compound with lower specific rotation was composed of one molecule of methyl ricinoleate and one molecule of methanol, both bound to diisocyanate to give [4-(1-methoxycarbonylamino)phenyl][4-(1-methoxy-1-oxo-9-octadecen-12-yloxycarbonylamino)phenyl]methane. No components were found of a struc-ture which might indicate the ancient, natural origin of the resinous material.
 
Keywords: resinous inclusions in coal, poly(oxyethylene)-poly(oxypropylene) glycol, double homologue mixture, methyl ricinoleate, urethanes derived from bis(4-isocyanatophenyl)methane, ESI mass spectra


Wiadomości Chemiczne, 2008, 62, 115.
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OKRUCHY. "BEŁKOTKA"

Ignacy Z. Siemion

Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław



Wiadomości Chemiczne, 2008, 62, 135.
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THE 40TH ANNIVERSARY OF THE FACULTY OF CHEMICAL TECHNOLIGY OF POZNAŃ UNIVERSITY OF TECHNOLOGY

Zenon Łukaszewski

Wydział Technologii Chemicznej, Politechnika Poznańska



Wiadomości Chemiczne, 2008, 62, 143.
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THE SYNTHESIS OF CORROLES

Beata Koszarna, Daniel T. Gryko

Instytut Chemii Organicznej PAN, ul. Kasprzaka 44 /52, 01-224 Warszawa
daniel@icho.edu.pl


Corroles, one carbon shorter analogues of porphyrins emerged a few years ago as an independent research area (Fig. 1) [1-3]. Their coordination chemistry, photophysics, synthesis, chemical transformations, electrochemistry and other properties have recently been studied in great detail [7-11]. Discovered in 1964 [15], for many years they have been mainly synthesized via a,c-biladienes cyclization [19-20]. Multistep a,c-biladienes preparation discouraged broader range of chemists from studying corroles (Scheme 2).

Since initial reports by Gross [17, 18] and Paolesse [16] revealing one-pot syntheses of meso-substituted corroles from aldehydes and pyrrole, this reaction has been subjected to many refining studies (Scheme 4, 5; Table 2) [23-28]. As a result yields have been improved to ~ 15%. The one-pot synthesis of meso-substitued A3-corroles from aldehydes and pyrroles consists of two independent steps. The first step is an acid-mediated electrophilic substitution to yield a mixture of various aldehyde-pyrrole oligocondensates including bilane (tetrapyrrane) - the direct precursor of corrole (Scheme 6). The second step is the oxidative ring-closure. Maximizing bilane formation while minimizing the formation of dipyrromethanes, tripyrrane and higher oligocondensate is a difficult task due to the similar reactivity of all these compounds [30-32].

Recently new and efficient conditions for the synthesis of meso-substituted corroles have been developed [33]. The first step, namely the reaction of aldehydes with pyrrole, was carried out in a water-methanol mixture in the presence of HCl. A relatively narrow distribution of aldehyde-pyrrole oligocondensates was controlled by their solubility in the reaction medium. After thorough optimization of various reaction parameters high yields of bilanes were obtained. As a result, many A3-corroles were obtained in the highest yield (~25-30%) reported to date.

Corroles bearing two various substituents at meso positions were synthesized for the first time from dipyrromethanes and aldehydes (Scheme 10) [35]. This method continues to prevail in the literature [36-38]. Performance of this reaction in H2O/MeOH/HCl mixtures allows to obtain trans-A2B-corroles in yields up to 56% (Scheme 11) [33]. Last developments in the chemistry of corroles make these compounds more accessible than respective porphyrins.
 
Keywords: corroles, porphyrins, electrophilic substitution, macrocyclization, oxidation.


Wiadomości Chemiczne, 2008, 62,165 .
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ELECTRONIC INTERACTIONS IN BINUCLEAR MOLYBDENUM NITROSYL COMPLEXES

Andrzej Włodarczyk, Piotr Romańczyk

Zakład Chemii Fizycznej, Wydział Inżynierii i Technologii Chemicznej
Politechnika Krakowska ul. Warszawska 24, 31-155 Kraków


Design and synthesis of redox active binuclear complexes in which metal centres are linked via bridging ligands enabling electronic and magnetic interactions between them are crucial for an understanding of key processes in chemistry and biology. In biological systems, such as proteins, electron transfer involves a charge transport over a considerable distance (>10 Å) [8-11,13-19]. On the other hand, long range electronic interactions are central in the development of potential elements for molecular electronics like molecule-sized wires, diodes, light activated switches, transistors (Fig. 1), logic gates etc. [1-7].

This article reviews some of the work performed in the area of bimetallic nitrosyl molybdenum complexes containing tris(3,5-dimethylpyrazol-1-yl)hydroborato ligand (Fig. 4). Numerous examples of mixed-valence species have been described, showing a wide range of behaviour from fully delocalized to valence-trapped systems of which electrochemical (voltammetry, Fig. 3), spectroscopic (EPR (Fig. 5), IR and UV-Vis/NIR spectroscopy) and magnetic susceptibility were studied. These results are summarised in Table 1. Many such complexes show exceptionally strong electrochemical (ΔEf) and magnetic exchange interactions (J) between metal centres depending on the features of the bridging ligand such as length, degree of conjugation, dihedral angles between aromatic rings, substitution pattern, and symmetry [28, 41]. For example, in [{Mo(NO)(TpMe2)Cl}2{4,4'-bipy}] (Fig. 9) ΔEf equals 765 mV, being an order of magnitude greater when compared to the {Ru(NH3)5}2+/3+ analogue, and J = -33 cm-1 [43, 68, 69]. Using 3,3'-dimethyl-4,4'-bipy as a bridge forces a twist between the two pyridyl rings and decreases both ΔEf and J down to 380 mV and 3.5 cm-1, respectively [42, 71]. The introduction of a saturated section into the bridge, which breaks the conjugation, e.g. in 1,2-bis(4-pyridyl)ethane ligand, considerably decreases ΔEf (105 mV) but does not exclude electronic and magnetic through-bridge interactions [43]. Recently a series of bimetallic complexes based on {Mo(NO)(TpMe2)}2+ centres comprising n-alkanediolate bridges (Fig. 12) have been prepared. These species exhibited intermediate metal-metal interactions (310 mV in ethane-1,2-diolate) [54, 55] which prompted investigation of electronic interactions through saturated alkyl chains by DFT [64].
 
Keywords: molybdenum nitrosyl complexes, bimetallic complexes, tris(pyrazolyl)borato complexes, electronic interactions, magnetic interactions.


Wiadomości Chemiczne, 2008, 62, 187.
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Ti(IV) AND Zr(IV) ALKOXO COMPLEXES WITH O-DONOR LIGANDS.
SYNTHESIS, STRUCTURAL CHARACTERIZATION AND APPLICATIONS

Piotr Piszczek

Wydział Chemii, Uniwersytet Mikołaja Kopernika, ul. Gagarina 7, 87-100 Toruń


Extensive studies of complexes of titanium(IV) and zirconium(IV) alkoxides with O-donor ligands observed for the last few years are a result of their wide applications in nanomaterial technologies. Various physicochemical properties of TiO2 and ZrO2 including high reference factor (n = 2,616-2,903 TiO2), low absorption in visible range, photoluminescence, high dielectric constant (εTiO2 = 120 for rutile), high stability and chemical resistance have significant influence on their use. Thin metal oxide layers are prepared by vaporization and condensation methods [1], hydrolysis in the flame [2], vacuum deposition, sol-gel techniques, and also chemical vapor deposition (CVD). The last two methods are most often used to prepare high quality ceramic materials, thin metal oxide layers, organic-inorganic hybrid polymers, dopped materials (M2O/M'; M = Ti, Zr; M' = Cu, Ag, Au, Pt, Pd) as well as mesoporous materials [3-15]. In both techniques a very important role is played by precursors, which influence CVD process, and the structure of deposited layers.

Ti(IV) and Zr(IV) alkoxides (M(OR)4) are usually used as CVD precursors of thin TiO2 and ZrO2 layers. However, high reactivity of M(OR)4 towards nucleophilic reagents, in particularly hydrolysis and condensation of metal alkoxides, lead to precipitation of oxo-polymers. In order to stabilize the alkoxo precursor, Ti(IV) and Zr(IV) complexes containing anionic bidendate groups, such as β-diketones, carboxylates, alkylamides, sulfonates have been studied [14-17]. In the presented paper, the review of synthetic methods and structural characterization of the following type of complexes [M(OR)4-x(L)x] (M = Ti(IV), Zr(IV), OR = alkoxo ligand, L = β-diketones, carboxylates) has been carried out. The volatile properties of these compounds as well as their low reactivity towards water caused that above mentioned complexes are used as TiO2 and ZrO2 precursors in CVD processes and therefore a special attention has been paid to this problem.

Substitution of alkoxo groups by β-diketonate ligands in the alkoxide/β-diketonate molar ratio of 1:1 makes possible the synthesis of monomeric complexes of the general formula [Ti(OR) 2 (β-diketonate) 2]. The use of an excess of β-diketonate (1:2) leads to the formation of dimeric complexes ([Ti(OR)3(β-diketonate)] 2 (Fig. 2) [27]. Sensitivity of these compounds to moisture was significant lower than the parent Ti(IV) alkoxides. Suitable volatility of the mentioned complexes and thermal decomposition to TiO2 caused that their use as CVD precursors is possible. Deposition experiments proved that pure TiO2 layers of anatase form were obtained at temperatures higher than 573 K using [Ti(dpm) 2 (OiPr)v] [25] and [Ti(mpd)(mdop)(m-OMe)] 2 [93] as precursors.

From Zr(IV) β-diketonate derivatives, only [Zr(OR) 2 (thd) 2] (R = OiPr, tBu) and [Zr(OiPr)3(thd)] 2 were used for the deposition of ZrO2 by CVD methods [98]. According to the literature reports, above mentioned β-diketonates were less reactive and easier to handle than parent alkoxides, but their volatility was significantly lower. ZrO2 layers were also prepared using [Zr(acac) 2 (hfip) 2] but in deposited films, traces of fluorine contaminations were observed [103].

Oxo-alkoxo carboxylate Ti(IV) derivatives were synthesized in reactions of Ti(IV) alkoxides with carboxylic acids (Fig. 4). The structure of these complexes consists of oxo-metallic skeletons (Fig. 5), which size and structure depends on (a) metal alkoxide/carboxylic acid molar ratio, (b) type of alkoxide and carboxylate ligand, and (c) reaction temperature. Results of these works suggest that Ti(IV) complexes, which structure consists of [Ti6O6(OR4)6(OOCR')6] (R = OiPr, nBu, iBu, R' = H, Me, tBu, CH2tBu, C(CH3)2Et, C6H4Oph) clusters are the most stable (Fig. 7) [34, 44]. These types of Ti(IV) complexes were also prepared in the reaction of Ti(IV) trimethylsiloxide with 2 fold exces of organic acids [45]. Thermolysis of [Ti6O6(OR4)6(OOCR')6] proceeds with their partialy decomposition and formation of a volatile and stable Ti(IV) alkoxide and Ti(IV) carboxylate [43]. Results of CVD experiments confirm that these types of complexes have promising properties as titanium dioxide precursors [88, 94]. Thin titanium dioxide films have been deposited in the temperature range 673-873 K on Si(111) substrates. The structure and surface morphology of the layers change with an increase of temperature from the large grain of TiO2 anatase (TD = 713-733 K), to close-packed crystals of rutile form (TD = 853-873 K).

A result of the reaction of Zr(IV) alkoxides with organic acids are oxo/hydroxo Zr(IV) carboxylate or oxo/hydroxo Zr(IV) carboxylate alkoxides (Fig. 9) [57-59]. Their low volatility and high thermal stability makes them unsuitable for CVD processes. Application of fluorinated carboxylate ligands increases the volatility of these compounds. ZrO2 layers have been deposited by CVD using ([Zr6O4(OH)4(OiPr)6(OOCR')6] (R' = C2F5, C3F7) as precursors, at ~853 K. Analysis of the literature data showed that carboxylate substituted oxozirconium complexes can be applied for the preparation of inorganic-organic hybrid polymers [104, 105].
 
Keywords: titanium(IV) and zirconium(IV) complexes, crystal structure, IR, NMR, thermal properties .


Wiadomości Chemiczne, 2008, 62, 209.
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REDOX-ACTIVE RECEPTORS OF CATIONS AND ANIONS

Katarzyna Zięba, Joanna Taraszewska*

Instytut Chemii Fizycznej Polskiej Akademii Nauk, ul. Kasprzaka 44/52, 01-224 Warszawa
*e-mail: jota@ichf.edu.pl


The electrochemical recognition of cationic, anionic and neutral guests is a fast expanding research area on the interface of electrochemistry and supramolecular chemistry. Its aim is the development of highly sensitive and selective receptors [2, 3]. The redox-active receptors usually consist of two units: the guest binding site and the redox-active unit. After complexation of a guest at the binding site, the changes of the electrochemical properties of redox-active center give information about the complexation. The idea of redox-active receptors is presented in Scheme 1.

The present review is devoted to different types of redox-active receptors for cationic and anionic guests. Receptors able to recognize cations are presented according to the mechanism of a communication between redox-active and binding units. These mechanisms are: through bonds communication, through space communication, direct coordination of a cation to redox-active center and the conformational change of redox-center mechanism.

In the next chapter are discussed the redox-active receptors for anions according to the type of the redox-active center. In complexation of anionic guests the major role plays the possibility of the creation of hydrogen bonds between anion and receptor.

The most extensively studied redox center was ferrocen. Nowadays, in the construction of redox-active receptors more often complexes of metal cations are used [53, 54].
 
Keywords: redox-active receptors, electrochemistry, complexation, cations, anions.


Wiadomości Chemiczne, 2008, 62, 237.
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TOWARD A BETTER UNDERSTANDING OF PHOSPHORYL TRANSFER REACTION: THE USE OF PHOSPHOROORGANIC BIOCIDES IN RESEARCH STUDIES

Witold Przychodzeń

Katedra Chemii Organicznej, Wydział Chemiczny Politechniki Gdańskiej, ul. Narutowicza 11/12, 80-952 Gdańsk
e-mail: witold@chem.pg.gda.pl


Among organophosphorus biocides (OPB), VX is the most toxic, but multi-ton production of less toxic OP pesticides, solvents, plasticizers, and engine anti-wear additives as well as their precursors can also have a detrimental impact on our health. V-gases have been feared as the "nuclear weapon" of poorer nations and terrorist groups because their manufacturing is relatively simple and the starting materials are readily available. Comparison of toxicity of OPB, of both synthetic and natural origin is presented in Table 1.

It is well-known that some OBP were used in ophtalmology. Rationally designed OBP can be active in treatment of Alzheimer or Parkinson disease [9-11] or as β-lactamase inhibitor in the future [12].

The extreme toxicity of V-gases often mandates research laboratories to employ safer model compounds called simulants instead of the actual compounds. Some examples of recently involved simulants are presented (Fig. 3) and the influence of their structure on reactivity is reported [13-14].

Many efforts have recently been performed in order to find new and effective methods of detection of OPB and their degradation products (Ch. 4). Although sophisticated chromatographic techniques are involved [15], they are not optimal for rapid detection. The most promising methods seem to be antibody-based recognition [18] and the use of chemical [17] and biological sensors [19].

A great deal of work is devoted to develop efficient methods capable of eliminating persistent OPB under comparatively mild conditions. Chemical methods with the emphasis on nucleophile promoted hydrolysis are the most preffered reaction. Especially, supernucleophilic reagents facilitate OPB hydrolysis and some of them act as strong oxidants [25-27]. Otherwise, enzyme-like systems including micelles and microemulsions have been used in decomposition by nucleophiles. It was found that OPB methanolysis can be accelerated with the use of lanthanium and cupric ions by a factor of 109 [29-32]. The use of reactive polymers, which are prone to transesterification [28] is quite a novel approach to the detoxification of OPB. This methodology allows immobilizing phosphoric residue on polymeric particles and completely removes OPB from their solutions (Fig. 6). Detoxification of VX is an extremely serious, yet unsolved scientific problem. Its hydrolysis (and oxidation) is a relatively slow process and proceeds to the formation of other toxic compounds (Fig. 5) [22]. A number of groups have looked at the creation of catalytic antibodies which can be used for the degradation of VX [13, 37-38]. Haptens bearing amine oxides, phosphorane and α-hydroxyphosphinate structures have been designed for the selection of antibodies in order to hydrolyse paraoxone and VX, respectivily (Fig. 8 and 9). Also, considerable efforts have been made concerning the hydrolysis of V-gases with enzymes [33-36].

Until now, reactivation of AChE is realized by only one family of antidotes known as pyridinum oximes although some improvements of their structure have been made [39-41] (Fig. 10).

Studies of uncatalyzed [44, 48-52] and enzymatic phosphoryl transfer (PT) and thiophosphoryl group transfer reaction [43-47] have been undertaken in various laboratories in an effort to understand the mechanism of this important biological process.

Additionally, few examples of improvements in OPB synthesis are presented (Fig. 13) which could have the influence on the progress in OPB-based research.
 
Keywords: phosphoroorganic biocides, phosphoryl transfer reaction, chemical and biological methods for the detection and detoxication of biocides, AChE inhibitors and reactivators.


Wiadomości Chemiczne, 2008, 62, 269.
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NON-NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITORS OF HIV

Andrzej Orzeszko 1*,2

1* Katedra Chemii, SGGW w Warszawie, ul. Nowoursynowska 159c, 02-787 Warszawa
e-mail: Andrzej_Orzeszko@sggw.pl
2 Instytut Chemii, Wojskowa Akademia Techniczna w Warszawie, ul. Kaliskiego 2, 00-908 Warszawa


This review attempts to briefly summarise the developments in anti-HIV therapy. The main attention was paid to the inhibitors of the virus enzyme reverse transcriptase (RT).

Until 1987, no anti-HIV drug has been available, but an understanding of life cycle of HIV has led to an identification of several possible drug targets. At present, most drugs that have been developed act against the viral enzymes: reverse transcriptase, protease, as well as integrase. However, a serious problem with HIV treatment is that the virus undergoes mutations extremely easy. This results in rapid resistance to antiviral drugs.

Non-nucleoside reverse transcriptase inhibitors (NNRTI's) have, in addition to the nucleoside reverse transcriptase inhibitors, protease inhibitors, integrase inhibitors and fusion inhibitors, gained a definite position in the treatment of HIV-1 infection. To date three NNRTIs: Nevirapine, Delaviridine and Efavirenz have been approved by the US Food and Drug Administration for clinical use [3-8].

NNRTIs snugly fit into a specific allosteric "pocket", located at some 10 Å from the catalytic site, of HIV-1 RT and thus disrupt its enzymatic activity [5-7, 17, 18]. Several studies have revealed a common mode of binding for chemically diverse compounds with their target site at the RT [5]. The inhibitors cause a repositioning of the three-stranded sheet in the p66 subunit containing the catalytic aspartic acid residues 110, 185 and 186. This suggests that NNRTIs inhibit HIV-1 RT by locking the active catalytic site in an inactive conformation. When bound into their pocket at the HIV-1 RT, the inhibitors maintain a very similar "butterfly-like" conformation. They roughly overlay each other in the binding pocket and appear to function as π-electron donors to aromatic side-chain residues surrounding the pocket [5].

Drug resistance is a key failure for treatment of HIV infection. The torsional flexibility of the inhibitors can generate numerous conformational variants and the compactness of the inhibitors permits significant repositioning and reorientation within the pocket. So, in this perspective, various new prototypes of NNRTI's were reported as potential lead compounds [20]. For example, Capravirine, Dapivirine as well as thiazolidinones belong to this group [24-29].
 
Keywords: anti-HIV drugs, non-nucleoside reverse transcriptase inhibitors.


Wiadomości Chemiczne, 2008, 62, 297.
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OKRUCHY. O OGNIU GRECKIM I PROCHU STRZELNICZYM. WYPISY Z LEKTUR PRZYGODNYCH

Ignacy Z. Siemion

Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław



Wiadomości Chemiczne, 2008, 62, ??.
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PORPHYRIN DERIVATIVES WITH AN ACETYLENE MOIETY

Anna Berlicka, Lechosław Latos-Grażyński

Zakład Chemii Porfiryn i Metaloporfiryn, Wydział Chemii Uniwersytet Wrocławski, ul. F. Joliot-Curie 14, 50-383 Wrocław


The monograph gives a review of literature on porphyrinoids containing an ace-tylene unit attached at macrocyclic perimeter or built into a coordination core. The inclusion of an acetylene fragment provides an unusual structural motif because of its symmetrical cylindrical structure, coordination ability towards metal ions and reactivity.

The synthesis, coordination properties and reactivity of porphyrin analogs with an ethynylene unit embedded in the macrocyclic skeleton have been described. Most of such macrocycles belong to stretched porphycenes and heteroporphycenes [8, 9]. The distinct class of expanded porphyrin analogs is delivered by very stable cyclooligothiophenediacetylenes with different size of the interior cavity [16]. A novel type of contracted heteroporphyrins namely dithiaethyneporphyrins, with an acetylene moiety introduced instead of one of pyrrole units, has been also characterized [17, 18]. These macrocycles display unique features of an [18]triphyrin(4.1.1) frame.

The introduction of an alkyne moiety outside porphyrinic macrocycle yields meso- or β-alkynylporphyrins [38-42, 71-75]. The synthetic pathways and spectroscopic properties of alkynylporphyrins are included in the second part of the presented review. These macrocycles are widely used as building blocks in the construction of conjugated oligomeric and polymeric porphyrins and metalloporphyrins [81-85, 89-93]. Moreover, the paper provides classification of such π conjugated systems, which are extensively explored in the analysis of charge or electron density transfer due to the strong electronic conjugation of acetylene with the π system of the porphyrin ring.
 
Keywords: porphyrins, heteroporphyrins, carbaporphyrinoids, alkynylporphyrins, expanded porphyrins, contracted porphyrins.


Wiadomości Chemiczne, 2008, 62, 339.
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MESOPOROUS CARBONS: SYNTHESIS AND PROPERTIES

Jerzy Choma*&, Mieczysław Jaroniec#, Aleksandra Zawiślak*

* Instytut Chemii, Wojskowa Akademia Techniczna, ul. Kaliskiego 2, 00-908 Warszawa, jchoma@wat.edu.pl
& Instytut Chemii, Uniwersytet Humanistyczno-Przyrodniczy Jana Kochanowskiego, ul. Chęcińska 5, 25-020 Kielce, choma@pu.kielce.pl
# Department of Chemistry, Kent State University, Kent, Ohio 44 242, USA jaroniec@kent.edu


Porous carbonaceous materials are widely used in everyday life and industry because they possess very high surface area, pore volume and unique physicochemical properties, including high adsorption capacity for many organic molecules. Porous carbons have been prepared for hundreds of years, however traditional methods used for their preparation allow rather for a limited control of pore sizes and volumes of micropores and mesopores, which in fact results in a broad distribution of pore sizes. The most common applications of porous carbons include adsorption, catalysis, gas storage, purification of air and water and electrochemical applications [1, 2].

This article presents a survey of literature devoted to new methods of synthesis and characterization of mesoporous carbonaceous materials. One of the major topics reviewed in this article is the synthesis of ordered mesoporous carbons (OMC) with a help of ordered mesoporous silicas (OMS) (Fig. 1) [7, 25], colloidal silica (Fig. 2 and 3) [11, 29, 40, 59] and colloidal silica crystals as hard templates [57]. In addition to the synthesis of OMC, this paper presents an overview of physicochemical properties of OMC, especially adsorption properties. The exemplary characteristics, which include BET surface area, pore volume and pore size distribution, are provided for selected carbon materials [29].

A special emphasis was placed on the method, which employs monolithic siliceous templates obtained by pressing colloidal silica followed by their impregnation with oxalic acid (catalyst), resorcinol and formaldehyde (carbon precursors), polymerization of carbon precursors, carbonization and template removal (Fig. 4) [60]. This method affords carbons with uniform spherical mesopores as well as carbon composites with inorganic nanoparticles (e.g., silver), which after additional activation (e.g., with KOH) give micro and mesoporous carbons with superior structural characteristics. A set of basic parameters for one of these carbons includes: the diameter of spherical pores of 26,8 nm, the BET surface area of 1300 m2/g and the single-point (total) pore volume of 4,3 cm3/g; however, only 0,19 cm3/g of the total pore volume belongs to micropores. After KOH activation the volume of micropores increased to 0,8 cm3/g, the BET surface area increased to 2300 m2/g, but the volume of mesopores was reduced to 1,8 cm3/g [60].

Another important topic reviewed in this article is the synthesis of mesoporous carbons from thermosetting polymers (e.g., phenolic resins) used as carbon precursors in the presence of block copolymers used as soft templates (Fig. 5) [29, 78, 79]. This new synthetic strategy affords mesoporous carbons in the form of monoliths, fibers and films and permits to scale up this process. Additional activation of the resulting carbons with KOH (Fig. 7) affords micro and mesoporous carbons with high surface area and large volumes of both types of pores, improving significantly their adsorption properties. A set of basic parameters for one of the soft-templated carbons includes: the BET surface area of about 500 m2/g, the total pore volume of 0,7 cm3/g and the pore width of about 9,7 nm. After KOH activation the BET surface area increased to about 900 m2/g, the total pore volume and the volume of micropores increased to 0,9 cm3/g and 0,22 cm3/g, respectively [79].

Novel ordered mesoporous carbons are not only attractive materials for various advanced applications but also for the development of accurate methods for characterization of porous solids. This article shows that in addition to such important characterization methods as transmission electron microscopy (TEM), scanning electron microscopy (SEM), and powder X-ray diffraction (XRD), adsorption of nitrogen, argon and other adsorbates (Fig. 8) is one of the key methods for the pore structure analysis, especially for the assessment of global properties of porous materials.
 
Keywords: mesoporous carbonaceous materials, synthesis, properties, porous structure.


Wiadomości Chemiczne, 2008, 62, 373.
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MODELS OF ACTIVATED CARBONS: PAST, THE PRESENT AND FUTURE

Piotr A. Gauden, Artur P. Terzyk, Sylwester Furmaniak

Wydział Chemii UMK, Katedra Chemii Materiałów, Adsorpcji i Katalizy, Zespół Fizykochemii Materiałów Węglowych, ul. Gagarina 7, 87-100 Toruń


The development of models of activated carbons is presented. We start from historical review of the concept of BSU (Fig. 1) [4, 5, 8-12] and models based on microcrystallites (Figs. 2 and 3). We show the most popular methods of investigation applied in the field of carbon chemistry (Tab. 1). The structure of common surface acidic and basic functional groups containing oxygen are discussed (Figs. 5 and 7), taking into account the basicity of carbon π-electrons forming the structure. Next, we show how carbon porosity can be modelled. The basic computer simulation methods applied for recovering of the structure and studying of adsorption on carbons are discussed (mainly GCMC and MD). Here also DFT and some recently proposed new Monte Carlo-type methods are shortly discussed. Next the concepts of modelling of carbon porosity are presented (Fig. 8). First models of ideal pores are discussed showing the approach of infinite and finite carbon pores. Next we discuss the concepts of finite graphitic pores and the methods of modelling. Based on literature we divide current construction methods of models of carbons. Discussing of the current approaches we start from the models of Bakaev [104], Segarra and Glandt [105], Dahn et al. [107], and Seaton et al. [108]. Next we discuss in detail the newest models proposed by Biggs et al. [53-57] (Figs. 9 and 10), Do et al. [58-61] (Figs. 11 and 12), Gubbins et al. [39, 62-69] (Fig. 13) and Harris et al. [8, 12, 70-77] (Figs. 15 and 16). All mentioned models are discussed with some nuances. Also some less popular models are mentioned, including those proposed by Acharya et al., Gavald et al., Cascarini de Torre et al., Smith and Kumar et al. Since carbon surface functionalities are discussed in the paper finally some results obtained from molecular simulations of adsorption on carbons are presented especially the results of simulations of water adsorption. Eventually, some aspects for future studies are given.
 
Keywords: adsorption, activated carbon, carbon models, computer simulations.


Wiadomości Chemiczne, 2008, 62, 403.
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MAGNETIC INTERACTIONS THROUGH HYDROGEN BONDS

Maria Korabik

Wydział Chemii, Uniwersytet Wrocławski, ul. F. Joliot-Curie 14, 50-383 Wrocław


Hydrogen bonds play a key role in interactions in biological structures, supramolecular chemistry, and crystal engineering [28, 29]. The development of supramolecular structure created by hydrogen bonds is a new challenge for the synthesis of materials, in order to study their magnetic behaviour [59, 62]. A role played by hydrogen bonds in the transmission of magnetic interactions is still not fully understood, but the number of magnetically coupled hydrogen-bonded systems is growing.

The present paper describes magnetic properties of copper(II) complexes [33] with nitrobenzoate and salicylate ligands where the system of hydrogen bonds O-H···O is the only path of magnetic interaction. Magnetic measurements in the temperature range 1.8-300 K show magnetic phase-transition at 6 K to antiferromagnetically coupled CuII dimers with singlet-tryplet energy gap 2J = -6.26 cm-1.

A variety of different supramolecular hydrogen bond structures [27, 33-52, 57-62] and significant changes in their magnetic properties were analyzed to show the role of hydrogen bonds in magnetic interactions. Magnetostructural correlation has been made taking into account both covalently bridging ligand and the existence of intermolecular hydrogen bonds. An evidence for hydrogen-bond-mediated exchange coupling has been observed in magnetic study as well as in DFT calculations [40, 48].

Intermolecular interaction has been generally treated as a nuance, but today, it has established itself as an important functional tool, tunable at will [59] in the design of nanosized magnetic materials and their dimensionally-expanded compounds [57-62]. Intermolecular magnetic exchange interactions through hydrogen bonds, can have a large influence on the quantum properties of single molecular magnets SMMs [59]. Hydrogen bonding leads to coupling of the magnetic effects of individual SMMs units and to different quantum behaviour. Even very weak hydrogen bond inter-molecular interactions demonstrate a possibility of switching from an original nanosized magnetic system to a correlated system, for example, from single molecule magnet SMM to single chain magnet SCM or from such nanosized magnets to a bulk magnet [59].
 
Keywords: copper(II) complexes, intermolecular magnetic exchange interactions, hydrogen bonds, nanosized magnetic materials.


Wiadomości Chemiczne, 2008, 62, 449.
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POLYYNE COMPOUNDS AND COMPLEXES. SYNTHETIC STRATEGY AND APPLICATIONS

Karolina Osowska, Sławomir Szafert

Wydział Chemii Uniwersytetu Wrocławskiego, ul. F. Joliot-Curie 14, 50-383 Wrocław


The previous two decades have witnessed a series of major breakthroughs in carbon allotrope chemistry [1, 2]. This field has attracted scientists from all disciplines and plays a leading role in the nanotechnology boom. A lot of discussion is devoted to the new polymeric sp carbon allotrope termed "carbyne", which until now remains an unsettled topic. In order to model and understand its potential properties research on known - natural and synthetic - polyynes or polyynediyl systems has been undertaken.

The review gives a brief summary on the results of this research. It describes isolation and properties of many natural polyynes. This includes diynes [13-21], triynes [22-26], and tetraynes [27, 28], which were derived from many natural sources [6-10]. Most of these compounds possess very interesting biological activities that range from antibacterial properties through antifunginal, antiseptic, anti-cancer and anti-HIV activity [11-12].

Next some of the synthetic organic and organometallic examples are presented. The former includes compounds with more than 20 carbon atoms in the chain that are often terminated with extremely bulky (even dendrimeric) [29-38] or heteroatom containing endgroups [39-45]. Such compounds constitute an ideal base for many theoretic calculations.

The classification of alkynyl complexes is given as well as few examples of crystallographically characterized long carbon chain organometallic compounds [55-56]. The review differentiates the complexes of main group and transition metals. The former are less represented but are often crucial in the synthesis of transition metal alkynyl complexes [57-60].

Next we summarized the most practical approaches to the synthesis of polyynes. The common pathway includes four steps: (1) synthesis of terminal group precursor, (2) introduction of acetylene fragment, (3) chain elongation, and (4) termination of the carbon chain including dimerization.

Methods for C?C introduction to organic compounds are represented by numerous homo and heterocoupling protocols. The most frequently used are Sonogashira [64-66] and Stille [67, 68] couplings although in some cases other methods (Negishi, Kumada-Tamao-Corriu or Suzuki coupling) are more effective. Instead, conventional synthesis of alkynyl complexes includes reaction of metal halides with common alkynylating agents as alkynyl compounds of group 1 metals [71-73] although more sophisticated methods are also known [74-82].

Chain elongation is the most important part of the polyyne synthesis. The major protocol for this step is Cadiot-Chodkiewicz coupling first introduced in 1957 [83]. Lately, many modifications of this method were developed although the main idea remained unchanged [84-87]. With time some other protocols were applied for this step from which the most interesting are Fritsch-Buttenberg-Wiechell [89-91] and elimination reaction [92-93].

Finally, organic and organometallic polyynes application potential is discussed. Apart from their use in synthetic organic chemistry [99-113] they are being utilized for the production of polymeric materials via topochemical crystal-to-crystal polymerization [118-120]. They also reveal some medical applicability [114-115].
 
Keywords: polyynes, Sonogashira coupling, Cadiot-Chodkiewicz coupling, topochemical polymerization, polyyne complexes.


Wiadomości Chemiczne, 2008, 62, 479.
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NEW ANTILEPROSY DRUGS

Krystyna Nowak, Piotr Suryło*

Instytut Chemii i Technologii Organicznej, Politechnika Krakowska
*Instytut Chemii i Technologii Nieorganicznej, Politechnika Krakowska ul. Warszawska 24, 31-155 Kraków
e-mail: kn@chemia.pk.edu.pl; pesur@chemia.pk.edu.pl


Leprosy is a chronic infectious disease caused by the bacterium Mycobacterium leprae which has been plaguing mankind for ages. The first effective medicine to treat that illness was dapsone (1946) and it has been used until now [1]. Since then, there has been developed only one more new drug, clofazimine (1), which is, together with dapsone, listed as medicine used to cure leprosy (J 04 BA).

The other drugs which are currently employed in leprosy therapy used to be utilised in treatment of other bacterial diseases.

Clofazimine (1) was first synthesised in 1954 and has marked antibacterial and anti-inflammatory effects [2-8]. The method of preparation of clofazimine (1) consists of two stages (Scheme 1) [9, 10].

Minocycline (3) is a semisynthetic antibiotic of the tetracycline group with the mycobactericidal activity, obtained by chemical modification of tetracycline derivatives [11-13]. The substrates to synthesise minocycline are the metabolism products of S. aureofaciens or S. psammoticus - 6-demethyltetracycline (4a) or 7-chloro-6-demethyltetracycline (4b) [14-16]. 6-Demethyl-6-deoxyteracycline (5) is obtained as a result of reduction of compounds 4a and 4b, which may be transformed in several ways into minocycline (3) (Scheme 2, 3, 4) [17-30].

Amongst the macrolide antibiotics also the semisynthetic derivatives of erythromycin A, such as clarithromycin (15), azitromycin (16) and telithromycin (17) show some anti-leprosy features [12, 26, 32, 33]. Telithromycin (17) was introduced to medicine in 1995 and belongs to the group of ketolides, the latest generation of macrolides [12, 39, 40-45].

Following the in vitro and in vivo research it has been stated that the fluoroquinolones demonstrate mycobactericidal activity (Table 1) [47-51]. The World Health Organisation (WHO) recommends the use of fluoroquinolones in the multidrug therapy (MDT) together with other chemotherapeutics [108-113].

Rifampicin (26), a drug from the ansamycin antibiotic group, turned out to be an extremely effective weapon against leprosy [72, 73]. It is produced by chemical modification of a fermentation product of S. mediterranei [31, 74]. Rifampicin derivatives rifapentine (27) and rifabutin (28) are manifesting strong reactivity against Mycobacterium leprae, sometimes even surpassing rifampicin (26) (Table 2) [31, 72].

In the treatment of leprosy it is important to cure not only the causes but also the effects of the disease. That is why a wide range of complementary drugs is introduced. Especially steroids such as prednisolone (30), prednisone (31), dexamethasone (32) and fusidic acid (34) are important. The enumerated above steroids have strong anti-inflammatory effects as well as prevent nerve damage leading to smaller and lesser disability [2, 85]. Dexamethasone (32) is particularly efficient in conjunction with azathioprine (33) [90]. In the case of fusidic acid (34) it has been proved that it reveals weak bacteriostatic activity against the Gram-positive bacteria, including Mycobacterium leprae [7, 26].

Leprosy treatment involves the use of huge doses of bactericidal and bacteriostatic drugs what may lead to a life-threatening shock. In such circumstances, the most valuable medicine seems to be thalidomide (35) [82, 102-105].

WHO has prepared some programmes of leprosy treatment, recommending a diversion from a single drug to multidrug therapy (MDT). Implementation of the MDT therapy brings about numerous advantages such as economic advantages, shortening of treatment time and particular drug resistance prevention [7, 11, 107-109].

Leprosy, despite the tiny number of effective medicines, is totally curable. There have been continuous signals about utilising common and popular antibacterial drugs in leprosy treatment. Yet, it should be taken into consideration, that all action taken against that disease is limited to fighting bacteria but not preventing transmission.
 
Keywords: leprosy, antileprosy drug, multidrug therapy, Mycobacterium leprae.


Wiadomości Chemiczne, 2008, 62, 511.
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DEATH OF THE BEAUTIFUL THEORY WHICH SAYS THAT CARBON DIOXIDE GOVERNS THE EARTH CLIMATE

Przemysław Mastalerz
(em. profesor Politechniki Wrocławskiej)

ul. Gliniana 23/17, 50-525 Wrocław


The theory that carbon dioxide rules the Earth's climate is so well established that any attempts to tell that it is false and harmful to world's economy are met with very fierce opposition. The opponents have not much to support their claims but are strongly backed up financially by those who are not able to abandon the wrong idea that our climate depends on the concentration of CO2 in the atmosphere. This old idea is disproved by the unquestionable fact that in the past there was no correlation of CO2 concentration with temperature.

The claims that there is a consensus concerning carbon dioxide and global warming were disproved by a letter of scientists to the Secretary General of United Nations. The letter warns against the politics of fighting global warming and against the acceptance of the "precautionary principle".

This article provides a very brief overview of past climates and of the effects of Sun on the climate on Earth. The role of cosmic rays is considered and explained. A quick excursion into deep space gives an idea of how the climate depends on the wandering of the Sun with its planets across the spiral arms of our Galactic.

Separate chapters include examples of attempts to scare the humanity with climatic disasters and of the role of left-wing politicians in climate science.
 
Keywords: carbon dioxide, climate, temperature, global warming effect, world's economy.


Wiadomości Chemiczne, 2008, 62, 531.
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OKRUCHY. V. "O ogniu czyśćcowym"

Ignacy Z. Siemion

Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław



Wiadomości Chemiczne, 2008, 62, 553.
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CHEMICAL SOLID-PHASE SYNTHESIS OF OLIGONUCLEOTIDES.
POSSIBILITIES AND LIMITATIONS OF SOLID-PHASE SUPPORTS

Izabela Burzyńska-Pędziwiatr, Lucyna Woźniak

Zakład Biologii Strukturalnej, Katedra Endokrynologii Ogólnej
Uniwersytet Medyczny w Łodzi, ul. Żeligowskiego 7/9, 90-752 Łódź
e-mail: iza_burzynska@yahoo.com


Synthesis of biopolymers (peptides, proteins and nucleic acids) has long been in the range of interest of numerous chemists. The primary structure of biomolecules consists of linear and repeating sequences of monomeric units (aminoacids, nucleic bases, sugars) in a specifically determined orientation. Therefore, chemical synthesis of biopolymers comprises a lot of identical, repetitive steps (condensation, chain elongation and purification).

Solid phase method is currently used also for the oligonucleotide [2, 3] (Figure 1) and oligosaccharide synthesis. There exist interesting applications of analogous approach to combinatorial synthesis of small molecules (Solid Phase Organic Chemistry - SPOC) [4, 5].

Automation of the phosphoramidite method of oligonucleotide synthesis process proposed by Caruthers [6] made an enormous impact on biological, medical and biotechnological sciences. It is beyond any doubt that this is the fastest and the most convenient method of oligonucleotide synthesis aimed at biological research. Solid phase synthesis has many advantages, however, it is not free of drawbacks either.

Depending on the synthesis method, various types of supports are used. An ideal support should have an appropriate and reactive chemical group on its surface, e.g. -NH2, -OH, -COOH, by means of which it is connected to the linker and the first unit of the monomer. Surface functionalization of the solid phase determines the number of available reactive groups and characterizes support loading expressed in micromoles per gram.

Nucleosides are attached to the support by a linker, the choice of which depends on the reaction conditions. The linker arm must be designed in such a way that it is adjusted to the cleavage conditions and deprotection procedures.

Depending on the synthesis purpose and the type of a oligonucleotide, various linker arms are used. They include: linker arms cleaved after synthesis, labile linker arms, universal linkers [21, 22], and the linker arms for deprotection of the immobilized products [26, 27].

Among numerous methods of oligonucleotide synthesis, the phosphoramidite method is the most common. The phosphoramidite approach (Figure 10) allows for obtaining both natural DNA/RNA and plenty of modified analogs (phosphorothioates, phosphoroselenoathes, triesters and others). Its alternative is the H-phosphonate method (Figure 11) [40-42]. Particular advantage of this method is that it can be used in the synthesis without protection of nucleobases.

Depending on its destination, the synthesis must be very carefully designed considering the strategy of group protection to make them stable under reaction conditions. A decision must be also made whether to use the phosphoramidite method or the H-phosphonate method taking also into account whether the product is to be immobilized on the support or not, which depends on expected results.
 
Keywords: oligonucleotide synthesis, phosphoramidite method, H-phosphonate method, supports, linkers.


Wiadomości Chemiczne, 2008, 62, 571.
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PROFILE OF STATHERIN - SALIVARY PROTEIN INVOLVED IN HOMEOSTASIS IN ORAL CAVITY

Dominika Jackiewicz-Barańska, Elżbieta Kamysz, Zbigniew Maćkiewicz

Wydział Chemii, Zakład Chemii Polipeptydów, Uniwersytet Gdańsk
i ul. J. Sobieskiego 18/19, 80-952 Gdańsk


Saliva is a gel resembling liquid, that acts almost as an organic tissue [1]. Saliva influences oral health through its non-specific physico-chemical properties [2]. It is composed of secretions from parotid, submandibular and sublingual glands, and smaller contributions come from minor salivary glands (e.g. palatal and labial). Saliva contains a number of proteins and polypeptides [2]. One of them is statherin a multifunctional 43-amino acid residue phosphominiprotein, containing vicinal phosphoserines at 2 and 3 positions and seven residues of tyrosine (Fig. 1) [7]. The relevant structural feature of statherin is N-terminal helix segment connected to a long poly--L-proline type II segment, which is followed by a short extended structure [14]. The gene for statherin is believed to be a single-copy gene and has been mapped to human chromosome 4q11-13 [20].

The statherin variants are SV1, SV2 and SV3 which comprise approx. 30% of the statherin family (Fig. 6). The ratios of statherin : SV1 and SV2 : SV3 are in both cases approx. 3 : 1. Statherin and SV2 are products of two different transcripts found in each of the major salivary gland. The variants SV1 and SV3 are derived by post-translational processing of statherin and SV2 [22].

Statherin is a multifunctional molecule that shows a high affinity for calcium phosphate minerals such as hydroxyapatite. It takes part in the calcium and phosphate transport during secretion in the salivary glands, is responsible for the protection and recalcification of tooth enamel, promotes selective initial bacterial colonization of enamel, and functions as a boundary lubricant on the enamel surface [38, 39]. Satherin levels of concentration in saliva could be in relation with the precancerous and cancerous lesions of the oral cavity [38].

The understanding of a profile and role of statherin has become important in medicine as the peptide could play a protective effect in oral cavity. However, the role and the functions of this peptide are still not well-know [38].
 
Keywords: saliva, salivary proteins, statherin, oral cavity.


Wiadomości Chemiczne, 2008, 62, 595.
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MACROCYCLIC COMPLEXES OF RADIONUCLIDES IN NUCLEAR MEDICINE

Agnieszka Majkowska, Aleksander Bilewicz

Zakład Radiochemii, Instytut Chemii I Techniki Jądrowej, Ul. Dorodna 16, 03-195 Warszawa


The use of radiometal-labeled small complexes and biomolecules as diagnostic and therapeutic agents is a relatively new area of medical research. Radiopharmaceuticals are radiolabeled molecules designed to deliver ionizing radiation doses to specific disease sites. Between the targeting biomolecule and a radionuclide a bifunctional ligand is inserted, one end of which is covalently attached to the targeting molecule either directly or through a linker whereas the other strongly coordinates a metallic radionuclide. Selection of a bifunctional ligand is largely determined by the nature and oxidation state of a metal ion. The metal chelate can significantly affect the tumor uptake and biodistribution of radiopharmaceuticals based on small biomolecules. This is because in many cases the metal chelate contributes greatly to the overall size and lipophilicity of the radiopharmaceutical. Therefore, the design and selection of the ligand is very important for the development of a clinically useful therapeutic agent. The requirement for high thermodynamic and kinetic stability of the metal complex is often achieved through the use of macrocyclic ligands with a functionalized arm for covalent bonding to the biomolecule.

In this review synthesis of bifunctional macrocyclic ligands and properties of radionuclide macrocyclic complexes used in nuclear medicine are presented. We describe results in two areas: substituted macrocyclic aza ligands for chelation of hard metal cations, and macrocycles containing sulphur for complexation of soft metal cations. Special attention was paid to stability of the complexes as well as to their lipophilicity, which affect biological properties of the formed radiopharmaceuticals. We also include a forecast of the near-term opportunities that are likely to determine practice in the next few years.
 
Keywords: nuclear medicine, radiopharmacy, macrocyclic ligands.


Wiadomości Chemiczne, 2008, 62, 609.
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CATALYTIC ACTIVITY OF SINGLE ENZYME MOLECULES

Jolanta Jakubaszek, Andrzej Molski

Pracownia Dynamiki Procesów Fizykochemicznych, Wydział Chemii UAM,
ul. Grunwaldzka 6, 60-780 Poznań


As early as in 1961, it has been demonstrated that turnovers of individual enzyme molecules can be detected [1]. In the nineties, advances in single-molecule methods, in particular in confocal microscopy (Fig. 1), made it possible to monitor more closely enzymatic turnovers at a single-molecule level [2-5]. This led to the discoveries of static disorder and dynamic disorder, and closely related memory effects in enzymatic turnovers [6-8]. Differences in activity of individual molecules of the same enzyme are called static disorder. Time-dependent fluctuations of enzymatic activity are called dynamic disorder. One manifestation of dynamic disorder is the fact that consecutive enzymatic turnovers are not statistically independent, which is called "memory effect". It is believed that static dis-order and dynamic disorder are related to conformational dynamics of enzyme molecules.

In this review we discuss current issues of single-molecule enzymology, in particular kinetic effects that are specific to single-enzyme measurements. First we review the conceptual basis of single-enzyme kinetics and the initial work on single enzymes. We focus on the ping-pong mechanism of bisubstrate enzyme reactions (Eqs. (1) and (2)), and consider fluorescence trajectories (Figs. 2 and 3) associated with enzymatic turnovers. Two cases are distinguished. In the first, fluorescence comes from an enzyme molecule and fluorescence intensity jumps called blinking carry information on enzymatic activity. Jumps between a fluorescent (on) and non-fluorescent (off) states (Eqs. (4), (5), and Fig. 2) indicate the moments when the photophysical state of an enzyme changes during enzymatic turnovers. In the second case, fluorescence comes from product molecules whereas enzyme and substrate are non-fluorescent. Fluorescence bursts on a trajectory indicate the moments when non-fluorescent substrate molecules are converted into fluorescent product molecules that subsequently diffuse away from the detection volume (Eqs. (8), (9) and Fig. 3).

In Section 1 we present selected experiments implying the effect of conformational dynamics on enzymatic kinetics. In Section 1.1, we discuss cholesterol oxydase and dihydroorotate dihydrogenase as examples of enzymes whose on-off fluorescence blinking is caused by chemical reactions at the enzyme active site. In Section 1.2 we discuss β-lactosidase and lipase B as enzymes which turnovers can generate fluorescent products from suitably chosen non-fluorescent substrates.

In Section 2, we review modeling and simulations of single-enzyme data. The aim of data modeling is to gain insight into single-enzyme activity through analysis of models of increasing complexity. Phenomenological models attempt to capture the essence of single-enzyme kinetics without going into molecular details. If a model is simple enough it may allow analytical solutions. For instance, a simple model of on-off blinking is given in Scheme (25). This scheme is capable of reproducing memory effect that can be visualized by a two-dimensional histogram of consecutive on and off times (Figs. 5a and 5b).

Finally, in the last section we present an outlook for single-molecule enzymology.


Wiadomości Chemiczne, 2008, 62, 635.
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NEW METHODS OF ULTRAMARINE PIGMENTS SYNTHESIS FROM ZEOLITES

Aldona Jankowska, Stanisław Kowalak

Uniwersytet im. A. Mickiewicza w Poznaniu, Wydział Chemii, ul. Grunwaldzka 6, 60-780 Poznań
aljan@amu.edu.pl


The natural ultramarine (lazurite, lapis lazuli) has been known and valued since the ancient times as semiprecious gem applied for jewelry, artistic works, decoration and painting. In Middle Ages it was used as excellent, but very expensive pigment. At the beginning of the nineteenth century a method of synthesis of artificial ultramarine has been discovered and it soon became a common inexpensive commercial product applied mostly for production of paints and as an optical brightener. The procedure included heating of the substrate mixtures (kaolin, sulfur, sodium carbonate, reducing agent) in kilns at high temperature (800°C). The technology of ultramarine production has not been substantially changed up to now, whereas the law regulations concerning environment protection imposed in the twentieth century could not accept a serious air pollution (SO2, H2S) always accompanying the production process. Therefore, searching for novel, environmentally friendly procedures becomes challenging.

Ultramarine is an aluminosilicate with sodalite structure that contains sulfur anion-radicals (mostly S3-) combined with Na+ cations embedded inside β-cages. The sulfur radicals play a role of chromophores (S3- blue, S3- yellow). Sodalite is a zeolite and the sodalite units (β-cages) are constituents of structure of several zeolites (LTA, FAU, LTN, EMT).

The use of zeolitic structures for encapsulation of sulfur anion radicals appeared very promising. The direct introduction of sulfur radicals from aprotic solutions of oligosulfides [27] was not successful but the thermal treatment of zeolites mixed with sulfur radical precursors (NaSn, S + alkalis) resulted in colored products analogous to ultramarine [24-26, 30, 31]. Zeolites A seem the most useful for preparation of sulfur pigments but other zeolites can be applied as well. The products of various colors (yellow, green blue and sometimes pinky) and shades can be obtained by choosing appropriate zeolite, radi-cal precursor, kind and content of alkaline cation in the initial mixture, temperature (400-800°C) and time of treatment. It was found that zeolite structure can be maintained upon the thermal treatment or it can be transformed (mostly towards SOD) under highly alkaline thermal treatment. The sulfur radicals can also be embedded inside smaller than β-cages (e.g. CAN) which favors a generation of smaller radicals (i.e. S2-) [39-42]. It is also possible to incorporate the sulfur compounds into zeolites during their crystallization and then a generation of radical upon heating. The sulfur pigments based on non aluminosilicate matrices (e.g. AlPO4-20) can be also obtained [38, 53].

Generally use of zeolites allows to obtain ultramarine-like pigments with broad range of colors under much milder than conventional conditions and with much lower emission of polluting agents.
 
Keywords: ultramarine, zeolites, molecular sieves, sulfur radicals, encapsulation.


Wiadomości Chemiczne, 2008, 62, 659.
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Pd-Ag, Pd-Pt, Pd-Au, Pt-Ag, AND Pt-Au BIMETALLIC SYSTEMS AS HETEROGENEOUS CATALYSTS OF REACTIONS WITH HYDROGEN

Piotr Matczak

Katedra Chemii Teoretycznej, Uniwersytet Łódzki, ul. Pomorska 149/153, 90-236 Łódź
E-mail: pmatczak@chemul.uni.lodz.pl


Heterogeneous catalysts play an important role in the manufacture of various chemical substances in large-scale processes, e.g. crude oil processing and organic synthesis [1]. Heterogeneous catalyst most often consists of a transition metal arranged on an oxide support [2]. The transition metal employed is usually one from Group 10 of the Periodic Table (Ni, Pd or Pt). The Group 10 metals are efficient catalysts of reactions with hydrogen. Such reactions occur in the above-mentioned crude oil processing and organic synthesis.

In large-scale applications some modifications of the catalyst properties are often necessary to increase the rate of an appropriate stage of catalyzed reaction and to avoid by-products. The change of the catalytic properties can be obtained by incorporating another metal into the catalyst. Heterogeneous catalysts in which the active part contains two metals are called bimetallic catalysts or, more generally, bimetallic systems [3, 4]. Research on bimetallic catalysts was initiated in the 1960s and since then these catalysts have become an object of increasingly in-depth investigations [5].

The aim of this review is to summarize the available knowledge on heterogeneous bimetallic catalysts. The review has been narrowed only to a few combinations of metals, i.e. Pd-Ag, Pd-Pt, Pd-Au, Pt-Ag, and Pt-Au.

In the first part of the review some general information on the forms of the bimetallic systems is presented. The term bimetallic system itself is quite broad and includes, among other, the following representatives (Fig. 1): alloys, surface alloys, monometallic monolayer or pseudomorphic overlayers arranged on the surface of the other metal, monometallic nanoparticles and clusters arranged on the surface of the other metal, alloyed nanoparticles and clusters, core/shell nanoparticles and clusters, and heteroaggregates. Recently, the last three of these representatives have been in the centre of interest [5, 6]. They offer properties very different from those characteristic of bulk materials [15].

Later, the methods of synthesis and structural characterization of the bimetallic systems are described. At present, the preparation of the bimetallic catalysts that exhibit an appropriate structure is difficult and expensive. Hence, further progress in this field is still required. Some new methods of preparation [7, 16-41], as well as many experimental [42-45, 48-67] and theoretical papers [69-77] on structural, energetic and electronic properties of the bimetallic systems are reviewed.

In the last part of the review the catalytic behaviour of the Pd-Ag, Pd-Pt, Pd-Au, Pt-Ag and Pt-Au systems is discussed in detail. The discussion concentrates on the catalytic reactions with hydrogen, e.g. hydrogenation, dehydrogenation, hydrogenolysis, etc. [106-137]. In such reactions the bimetallic catalysts exhibit higher selectivity than the monometallic ones. They also have better resistance to deactivation. At the very end of this review the theoretical investigations on H2 dissociation and H adsorption on the bimetallic systems have been mentioned [138-155].
 
Keywords: heterogeneous catalysis, bimetallic catalyst, hydrogen.


Wiadomości Chemiczne, 2008, 62, 683.
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DETERMINATION OF THE ABSOLUTE CONFIGURATION BY NUCLEAR MAGNETIC RESONANCE

Renata Kołodziejska, Lidia Jasińska, Aleksandra Karczmarska, Marcin Dramiński

Katedra i Zakład Chemii Ogólnej, Collegium Medicum w Bydgoszczy UMK Toruń
ul. Dębowa 3, 85-626 Bydgoszcz


In relation to a very limited scale of tolerance of organisms to different geometrical isomers it has been imperative to invent a method which would enable a precise and fast evaluation of a spatial structure of optically active compounds. Using a spectroscopic method of nuclear magnetic resonance (NMR) proved to be an excellent solution. In order to define an absolute configuration by means of NMR, the enantiomeric mixture must be transformed into diastereoisomeric one by adding chiral auxiliary substituents.

We distinguish three types of chiral auxiliary reagents: CDAs (chiral derivatizing agents), CSAs (chiral solvating agents), CLSRs (chiral lanthanide shift reagents). Chiral derivatizing agents are the most frequently used in analyses. The condensation reaction of an auxiliary compound with enantiomer may be single or double derivatization.

In case of a double derivatization, 1H NMR spectra of two diastereoisomers obtained as a result of condensation of (R)- and (S)-CDAs with the substrates are compared. The changes in the chemical shifts of the substituents L1 (the most bulky substituent) and L2 (the least bulky substituent) asymmetric carbon of the substrate in the two derivatives (R)- and (S)-CDAs is defined as ΔδRS. The ΔδRS value is the difference between the chemical shift in the (R)-CDAs derivative (δ(R)) and (S)-CDAs derivative (δ(S)) for the substituents L1 (ΔδRSL1) and L2 (ΔδRSL2) (Figure 2).

In case of a single derivatization, the tested enantiomer is combined with only one enantiomer ((R)- or (S)-CDA). In the single derivatization ΔδAR (ΔδAR = δ(A)-δ(R)) is the difference in the chemical shifts of the substituents L1 and L2 of a derivative and a free substrate (Figure 3) [1].

Among these auxiliary reagents are MPA (methoxyphenylacetic acid), MTPA (methoxytrifluoromethylphenylacetic acid), 9-AMA (9-anthrylmethoxyacetic acid), BPG (boc-phenylglycine), 9-AHA (ethyl 2-(9-anthryl)-2-hydroxyacetate), PGME (phenylglycine methyl ester), and PGDA (phenylglycine dimethyl amide). These reagents are currently being used to determine the absolute configuration of primary alcohols (Figure 4), secondary alcohols (Figure 5), tertiary alcohols, diols [2-5], triols [6], primary amines (Figure 6, 7), secondary amines (Figure 8), and carboxylic acids (Figure 9).

Other methods of determining absolute configuration such as HPLC-NMR or "mix and shake" method are currently investigated - HPLC-NMR method allows determining the absolute configuration of enantiomeric mixture as well as a pure enantiomer, the use of semipreparative column allows to precisely distinguish the obtained derivatives, which undergo the spectroscopic analysis (Figure 11) [1].

The "mix and shake" method allows determining the absolute configuration in a few minutes and without any additional separation methods. The derivative/s is/are prepared by simply mixing a solid matrix-bond auxiliary reagent with a chiral substrate and NMR spectra of the resulting derivatives are obtained without any further manipulation (Figure 12) [7].

 
Keywords: absolute configuration, nuclear magnetic resonance, auxiliary reagent, single and double derivatization.


Wiadomości Chemiczne, 2008, 62, 709.
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CHROMATOGRAPHIC METHODS OF AIR POLLUTION ANALYSIS AT THE COMMUNAL MANAGEMENT FACILITIES

Anna Sadowska-Rociek1, Magdalena Kurdziel2

1 Małopolskie Centrum Monitoringu i Atestacji Żywności,
Uniwersytet Rolniczy im. Hugona Kołłątaja w Krakowie, ul. Balicka 122, 30-149 Kraków
2 Wydział Chemii Uniwersytetu Jagiellońskiego, ul. Ingardena 3, 30-060 Kraków


Communal management facilities like composting plants or landfills are found to be significant sources of air pollution in the environment. Air pollution is caused by chemical compounds that are naturally generated during biological decomposition of organic waste. Most of these substances belong to the volatile organic compounds (VOC). They can be classified into the groups: aliphatic and aromatic hydrocarbons, alcohols, aldehydes, ketones, acids, esters, chlorinated hydrocarbons and sulphur and nitrogen containing compounds. Their emissions to the atmosphere cause serious environmental concerns like potential health hazards, global warming, ozone layer damage and finally unpleasant odours that are the most important nuisance to citizens living in the vicinity of communal management objects. In the recent years the growing public concern about living conditions and the state of environment has resulted in the development of new analytical approaches suitable for monitoring and examining the volatile organic compounds in the air.

This article provides a review of the most frequently employed gas chromatographic methods used for determination of air pollutants emitted from communal management facilities. Gas chromatographs equipped with various types of columns and detectors (FID, PID) and coupled with mass spectrometers (GC/MS), olfactory detection port (GC/ODP) remain nowadays the most widely used and very suitable devices to investigate the presence and concentration of landfill odorants in the air [1-3].

In the article the above-mentioned methods are summarized and discussed.

The sampling technique in the analysis of gases is often the crucial point of the whole procedure. The most popular techniques of sample preparation including dynamic and passive enrichment on sorbents, followed by thermal desorption or extraction, solid-phase microextraction (SPME) or the modern approaches like use of the flux chamber [4, 5] are also described.

Finally, the review covers the topic of miniaturization of gas-chromatographic instruments. Micro gas chromatographs (μGC) and portable gas chromatographs provide the possibility of on-site analysis without the risk of sample contamination or destruction. They are easy to operate and work on-line, giving immediate results, which permit to monitor the level of pollution in the real time and follow the time evolution of landfill emissions [6].

In the Table 1 some examples of volatile organic compounds determination recently carried out in different places of the world are presented.
 
Keywords: communal management facilities, gas chromatography, air sampling, microchromatography, air pollution.


Wiadomości Chemiczne, 2008, 62, 733.
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OKRUCHY. VI. WYNALAZCY Z NIEOSPOLITEJ RODZINY

Ignacy Z. Siemion

Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław



Wiadomości Chemiczne, 2008, 62, 747.
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APPLICATION OF DESILYLATIVE COUPLING OF VINYLSILANES AND ETHYNYLSILANES IN SEQUENTIAL REACTIONS IN ORGANIC SYNTHESIS

Wiesław Prukała

Zakład Chemii Metaloorganicznej, Wydział Chemii, Uniwersytet im. Adama Mickiewicza w Poznaniu, ul. Grunwaldzka 6, 60-780 Poznań


An efficient formation of carbon-carbon bonds belongs to one of the most important transformations in synthetic chemistry. The reaction is predominantly catalyzed by the late transition metals [1, 2]. Traditional methods that have been employed, to accomplish this transformation include Stille and Suzuki reactions. However, due to a number of drawbacks inherent to the substrates used in these reactions, organosilicon reagents have emerged as competitive alternatives (the facility of preparation and purification of silanes, their high stability, and low-molecular weight). Because of the low polarizability of the C-Si bond, the silicon function must undergo nucleophilic activation to induce migration of a transferable group onto the organopalladium species (transmetallation) [3-8]. The family of palladium-based catalysts, used in the desilylative coupling reaction (DC), tolerates the presence of the majority of functional groups.

The paper gives a review of literature focused on the application of desilylative coupling in sequential reactions published till the end of 2007. The activity of different catalytic systems based on palladium compounds in desilylative coupling reactions has been characterized. The influence of some substituents and activators on the reaction as well as their mechanisms has been presented [36, 41, 94-104]. It is remarkable, that the two entirely different mechanisms can be operative for both fluoride and fluoride-free silanolate couplings [104-110], and that both are highly efficient room temperature reactions.

Alkenylsilanes, used in sequential reactions, can be efficiently prepared by several stereo- and regioselective methodologies involving classical stoichiometric routes from organometallic reagents and, more recently, transition-metal-catalyzed transformations of alkynes and silylalkynes (via the hydrosilylation, Sonogashira reaction), alkenes (the dehydrogenative silylation [10, 12, 13], cross-metathesis [9-11], Heck reaction), and other silicon derivatives.

Moreover, the paper provides a characterization of the desilylative coupling reaction (DC) conditions. Several independent sequential reactions (one-pot, tandem reaction), e.g. RCM/DC, Stille/DC, Heck/DC, Sonogashira/DC, cross-metathesis/DC, silylative coupling/DC etc., and their applications to the synthesis of biologically active compounds have been presented. The paper is completed with a list of the most important, in the author's opinion, monographs and review works on the application of the desilylative coupling catalysed by palladium compounds in organic synthesis.
 
Keywords: desilylative coupling, sequential reactions, palladium catalysts, organic synthesis


Wiadomości Chemiczne, 2008, 62, 779.
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DEVELOPMENT OF THE POROUS STRUCTURE OF ACTIVE CARBONS OBTAINED BY PHYSICAL AND CHEMICAL ACTIVATION OF FOSSIL COALS

Piotr Nowicki*, Helena Wachowska

Uniwersytet im. Adama Mickiewicza w Poznaniu, Wydział Chemii, Zakład Chemii i Technologii Węgla
ul. Grunwaldzka 6, 60-780 Poznań
*e-mail: piotrnow@amu.edu.pl


Increasing interest in sorption materials is stimulated by the development of new industrial technologies and the necessity to meet the increasingly restrictive standards aimed at the environment protection. From among the available range of sorption products, of the greatest importance are adsorbents obtained from coal, in particular active carbons.

The growing use of active carbons is a consequence of the readily available resources, their high mechanical and chemical resistance and easy degradability. Certain applications of active carbon require high adsorption capacity or high selectivity, therefore, many attempts have been undertaken to obtain sorbents showing well-developed surface area and enhanced sorption capacity towards certain adsorbates. These properties can be achieved by physical and chemical activation.

This paper presents the review of literature on the methods of chemical and physical activation of coal and the effects of particular parameters of these processes on the textural properties of the active carbon obtained. Much attention has been paid to the process of chemical activation.
 
Keywords: active carbons, carbonization, activation


Wiadomości Chemiczne, 2008, 62, 827.
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ANIONIC POLYMERIZATION WITH ELECTRON-TRANSFER REAGENTS

Zbigniew Grobelny,* Andrzej Stolarzewicz, Marcin Szczepański, Beata Piekarnik

Instytut Nauki o Materiałach, Uniwersytet Śląski, ul. Bankowa 12, 40-007 Katowice
*e-mail: ansto@us.edu.pl


This work describes the polymerization processes with electron-transfer reagents. Alkali metals, salts of aromatic hydrocarbons radical anions, and solutions of alkalides, i.e. salts containing alkali metal anions and complexed alkali metal cations, belong to such species [33-39].

The alkali metals transfer one electron to vinyl and diene monomers in the heterogeneous systems [54-73]. The radical anions are also able to transfer one electron [74, 77-82], however, in some cases they behave as nucleophiles [82-85] or bases [86]. These initiators are applied for the polymerization of vinyl and oxacyclic monomers in homogeneous systems. Both of them are named single-electron-transfer (SET) reagents.

The alkalides are two-electron-transfer (TET) reagents. Among them potassium potassides K-, K+(18-crown-6) and K-, K+(15-crown-5)2 in tetrahydrofuran solution are mostly used for the polymerization of various monomers [53]. The initiation with these salts is usually a multistage process. An organopotassium compound is formed as the intermediate product which after the protonation by crown ether becomes the real initiator of the polymerization of vinyl monomers [92, 93, 97, 100]. The organometallic intermediate can be also protonated by the monomer or can decompose with the elimination in the systems containing oxiranes [107, 110-113] or lactones [127]. Potassium alkoxides or potassium salts of carboxylic acids, respectively, are the genuine initiators in this case.

Crown ethers, known as the stable activators of chemical reactions, can participate in these processes as the reagents [107, 110, 116]. In the ring-opening reaction they form unsaturated potassium alkoxides which serve as the additional initiating agents [53, 97].
 
Keywords: electron-transfer, alkali metals, radical anions, alkalides, anionic polymerization, diene and vinyl monomers, oxiranes, lactones


Wiadomości Chemiczne, 2008, 62, 849.
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MAGNESIUM COMPOUNDS WITH ARYLOXO LIGANDS - INITIATORS OF LACTIDE POLYMERIZATION

Jolanta Ejfler

Wydział Chemii, Uniwersytetu Wrocławskiego, ul. F. Joliot-Curie 14, 50-383 Wrocław
e-mail: je@wchuwr.pl


Magnesium alkoxides and aryloxides are systematically explored in various kinds of chemical processes and among other, their use as reagents in organic transformations [1-5], supports or catalyst components in polyolefin industry [6, 7], chemical precursors for advanced materials [8-10], as well as initiators for the polymerization of cyclic esters [11, 12] are worth mentioning.

Over the past few years we have witnessed an increasing research on the use of magnesium aryloxides in the synthesis of new, biodegradable polymers, which have been preferential candidates for applications in medicine, pharmacy and production of eco-friendly bulk packing materials [13-15, 54-56]. Ready availability of monomers from inexpensive, renewable resources and the fact that resulted materials do not degrade the environment are an additional asset.

Biodegradable polymers for the biomedical applications are preferably obtained using initiators containing non-toxic metals, and aryloxides of metals such as magnesium are especially interesting in this context.

Despite the high utility limited number of magnesium alkoxides and aryloxides reported in the literature have a well-defined structure proved by X-ray analysis, which is required to design "single-site" catalysts. However, it is possible to identify and characterise certain types of frameworks.

Homoleptic magnesium bis-aryloxides depending on synthesis procedures and ligand structure can crystallise as monomers [12, 40, 44], dimers [47, 48], trimers [47, 48] and tetramers [47, 48] with the coordination number ranging from three to six. Among them candidates of primary importance for the application in the ring-opening polymerization (ROP) of cyclic esters are monomeric compounds. Up to now, however, only few examples of such species displaying the certain activity in living polymerization have been published [60-63]. Extremely important are homoleptic compounds able to act as initiators for ROP in presence of exterior alcohols which form end-groups in the resulting polymer [12, 50]. This constitutes a chance for the polymer chain modyfication achieved by simple introduction of functional groups and enable to obtain new drug-polymer complex.
 
Keywords: magnesium, arylokso complexes, initiators, lactide polymerization


Wiadomości Chemiczne, 2008, 62, 875.
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CHEMISTRY AND BIOLOGICAL ACTIVITY OF GARLIC (ALLIUM SATIVUM)

Halina Kwiecień

Zakład Syntezy Organicznej i Technologii Leków, Instytut Technologii Chemicznej Organicznej,
Politechnika Szczecińska Al. Piastów 42, 71-065 Szczecin
e-mail: halina.kwiecien@ps.pl


Garlic (Allium sativum) has historically been one of the most common vegetables to serve as a both spice and medical herb in many countries.

One of the outstanding features of the chemical composition of garlic is the large amount of unique organosulfur compounds, which provide its characteristic flavor and odor and most of its potent biological activity. Two classes of primary organosulfur compounds are found in whole garlic cloves: γ-glutamyl-S-alk(en)yl-L-cysteines and S-alk(en)yl-L-cysteine sulfoxides (alliin, metiin, propiin, isallin) (Fig. 1, 2) [5-15]. When garlic is crushed or cut, S-alk(en)yl--L-cysteine sulfoxides are exposed to the enzyme alliinase and thiosulfinates, via intermediate sulfenic acids are formed (Fig. 6) [29-33]. The major thiosulfinate, allicin is a reactive intermediate species that can be transformed, into a variety of compounds including diallyl, methyl allyl and mono- di-, tri-, tetrasulfides, vinyldithiins and ajoenes (Fig. 7-9) [37-49]. Garlic belongs to the Allium species, which accumulate only fructans as their nonstructural carbohydrates [52-59]. Garlic is also known for its production of some unique furostanol saponins, e.g. proto-eruboside-B and sativoside-B1 (Fig. 10-12) [60-63]. The Allium species also contain high levels of flavonides, including apigenin, myricetin and quercetin (Fig. 13) [64, 65], moderate levels of vitamins as well as free amino acids (Arg, Gln, Asn, Glu, and Lys) [66-69]. It was found that the amino acid fraction of Aged Garlic Extract (AGE) contain Maillard reaction products, N-fructosyl glutamine (Fru-Glu), -(1-deoxy-D-fructos-1-yl)-L-arginine (Fru-Arg) (Fig. 14, 15) [74-76], as well as tetrahydro-β-carboline derivatives (Fig. 16, 17) [77-82]. Recently, allixin (Fig. 18), a novel phytoalexin, with the structure 4H-pyran-4-one, as a novel substance with neurotrophic activity has been reported to by synthesized by garlic [83-85]. Garlic has the ability to accumulate the selenium from soil and the major selenium compound in both Se-enriched and unenriched garlic was identified as γ-glutamyl-Se-methyl selenocysteine along with lesser amounts of Se-methyl selenocysteine, selenocysteine, selenomethionine among other compounds (Fig. 19) [86-96].

Pharmacological investigations have shown that garlic has a wide spectrum of actions, not only it is antimicrobial [97], but it also has beneficial effects in regard to cardiovascular and cancer diseases [2, 3, 14, 42]. A number of organosulfur substances derived from garlic such as allicin, allicin-derived organosulfur compounds including sulfides, ajoene, steroidal saponins, flavonides, Fru-Arg, Fru-Glu, organic seleno-compounds and tetrahydro-β-carboline derivatives have been found to have strong antioxidant properties. It has been suggested that garlic can prevent cardiovascular disease, inhibit platelet aggregation, decrease the synthesis of cholesterol and prevent cancer. Thus it may either prevent or delay chronic diseases associated with aging.
 
Keywords: garlic; γ-glutamyl cysteine, cysteine sulfoxides, allin, alliinase, thiosulfinates, allicin; sulfides, ajoene, dithiins, fructans, saponins, organic seleno-compounds, carboline derivatives, allixin, antioxidant, antimicrobial, cardiovascular, anticancer activity


Wiadomości Chemiczne, 2008, 62, 901.
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OKRUCHY. VII. O "MANIFEŚCIE PANA ASPIRYNY", "KWASIE ARGININOBURSZTYNOWYM" I "JONIZACJI".
INSPIRACJE CHEMICZNE W SZTUCE WSPÓŁCZESNEJ.

Ignacy Z. Siemion

Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław



Wiadomości Chemiczne, 2008, 62, 943.
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Prof. dr. hab. inż. Józef J. Ziółkowski, Dr.H.C. Mult, (1934-2008)- An Obituary

Anna Maria Trzeciak

Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław


Wiadomości Chemiczne, 2008, 62, 769.
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BRIDGED POLYSILSESQUIOXANES - SYNTHESIS, STRUCTURE AND ADSORPTION PROPERTIES

Mariusz Barczak*, Andrzej Dąbrowski

Wydział Chemii, Uniwersytet Marii Curie-Skłodowskiej, Plac Marii Curie-Skłodowskiej 3, 20-031 Lublin
*e-mail: mbarczak@umcs.pl


Bridged polysilsesquioxanes (BPs) are an emerging group of organic-inorganic hybrid materials where organic moieties are built into a siloxane matrix by stable covalent carbon-silicon bonds [1, 2]. The simplest precursors of BP xerogels can be presented as bis(trialkoxysilanes) structures M-(SiX3)n, where X is the hydrolyzable group, and M denotes the organic bridge (spacer). By means of the appropriate precursors in the reaction of hydrolytic polycondensation it is possible to design on a molecular level the considered materials keeping control over their characteristics.

Bridges can have a different nature, e.g. they can be representative of homologue series of saturated hydrocarbons or aromatic hydrocarbons. In fact, one of the greatest advantages is a huge range of sol-gel processable monomers with different organic bridges. As they can vary in composition, length, geometry of substitution and rigidity it makes possible to affect the chemical and physical properties of final materials, including structure-adsorption properties by the choice of the precursor. Flexibility of an organic bridge plays a key role in such a behavior: materials with long elastic bridges are more susceptible to collapsing during the last stages of the sol-gel treatment (ageing and drying). Furthermore, at the same length of an organic bridge, formation of mesoporosity materials is observed in the alkaline medium, while in the acid medium - formation of microporosity. The influence of factors such as flexibility of the bridge, monomer concentration, type of catalyst, ageing time, etc. on textural characteristics of BPs materials has been widely described in the literature [1-8] and is also shortly discussed in this article.

As the formation of these solids is kinetically controlled all parameters of a synthesis are able to influence the kinetics of the sol-gel process, what in result affects both the physical and chemical properties of the final materials (19, 20, 24-29). Thus, porosity, specific surface area, pore volume or surface chemistry can be tuned during sol-gel processing by a proper choice of monomers and synthesis conditions. Some illuminative examples of influencing the structure-adsorption characteristics has been discussed here.

The possibility of tailoring of the above-mentioned final properties makes bridged polysilsesquioxanes potential candidates in adsorption application. Up to date several works have been published in the literature describing such attempts. In this paper we briefly discuss the synthetic strategy, creation of porosity and some examples of the usage of BPs as adsorbents. Several research groups have been using these materials with different bridges (see Figure 10) to adsorb different metal ions such as Ag(I), Hg(II), Au(III), Pt(IV), Pd(II) and Rh(III) [68], Co(II), Cd(II), Cu(II), Ni(II), Zn(II), Mo(VI) and U(VI) [7, 69], La, Ce, Pr, Nd(III), Pm, Sm(III), Eu, Gd, Tb, Dy, Ho, Er(III), Tm(III), Yb, Lu [70], V(VI), Mo(VI), W(VI), Th(IV) and U(VI) [71]. Ethylene- and phenylene-bridged xerogels prepared via a surfactant template approach have been used as sorbents of phenols from solution [75]. Ethylene- and phenylene-bridged polysilsesquioxanes functionalized with amino and thiol groups have been successfully tested as adsorbents of volatile organic compounds such as: hexane, heptane, cyclohexane, benzene, and triethyloamine from the gas phase [76].

Examples shown in the article testify to a great potential of these group of hybrid materials as sorbents. BPs can partially fill the gap caused by a limited use of other type of sorbents due to their complex production technology, low chemical and mechanical stability, low efficiency or selectivity. Two significant advantages should be mentioned here. First is the possibility of a homogenic distribution of organic moieties accessible to the adsorbate particles. It allows the creation of adsorption sites which force selectivity of the adsorption process by promoting a particular type of adsorption force, for example donor-acceptor or π-π interactions. Secondly, the precise control of parameters such like the specific surface area or pore diameter induces adsorbents with predetermined characteristics. Such simultaneous control over the porosity and surface chemistry is a great advantage of bridged polysilsesquioxane materials.


Keywords: hybrid materials, bridged polysilsesquioxanes, adsorbents, adsorption, porosity, sol-gel, functionalization.


Wiadomości Chemiczne, 2008, 62, 977.
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MODIFIED ACTIVE CARBONS - PREPARATION AND PROSPECTIVE APPLICATION

Piotr Nowicki, Helena Wachowska

Uniwersytet im. Adama Mickiewicza w Poznaniu, Wydział Chemii, Zakład Chemii i Technologii Węgla, ul. Grunwaldzka 6, 60-780 Poznań


The attractive properties of active carbons are determined by the well-developed surface area and the type, number and mode of bonding of different heteroatoms (oxygen, sulphur, nitrogen, boron, phosphorus, chlorine) with the carbon surface [3-16].

Recently, much attention has been devoted to oxygen and/or nitrogen-enriched active carbons because of a wide gamut of their applications: for adsorption of compounds of acidic character such as SO2, H2S, NOx, CO2 from the gas phase [77-90] or for adsorption of metal ions [96-100]. Modified active carbons are also very effective in removal of many organic compounds, such as aromatic and aliphatic amines or phenol and its derivatives [101-107]. Of particular importance is the application of these carbons for production of electrodes in electrochemical capacitors in order to increase their capacity [21, 61, 117-121].

This article presents a survey of literature devoted to methods of synthesis and application of modified active carbons. A special emphasis was placed on the method of preparation nitrogen-enriched active carbons.
 
Keywords: active carbons, chemical treatment, surface functional groups, oxidation, nitrogen introduction.


Wiadomości Chemiczne, 2008, 62, 999.
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CONTEMPORARY AND PROSPECTIVE EXPLOSIVES

Stanisław Cudziło

Wojskowa Akademia Techniczna, ul. S. Kaliskiego 2, 00 908 Warszawa
scudzilo@wat.edu.pl


The replacement of black powder with nitro compounds in the middle of the 19th century revolutionized warfare, mining and civil engineering. The performance of the explosives that came into use at that time and which are still commonly used (nitroglycerine, nitrocellulose, trinitrotoluene) is three times higher than that of black powder. Within the next 150-year evolutionary development of explosives, their performance has been increased by about 60%. During that period, useful explosives were searched among organic compounds containing carbon, hydrogen, nitrogen and oxygen. The search was quite successful. For example stable caged nitroamines (HNIW, Fig. 3) were synthesized which densities are higher than 2 g/cm3 and detonation velocity exceeds 10 km/s. Recently, potential candidates for high energy density materials (HEDM) have been observed among meta-stable compounds (e.g. all-nitrogen compounds), molecular composites where fuel and oxidizer are mixed at a molecular level or nano-systems of reactive materials. It is assessed that in this way useful explosives can be produced with performance even ten times higher than that of HMX - the best explosive that is in use today. Such an increase in energy content would make possible miniaturization of ammunition and the fire power of small arms would become comparable to the contemporary artillery. This means not only enormous change in the battlefield tactics but also new threats of terrorist attacks on the critical infrastructure.
 
Keywords: explosive compounds and mixtures, primary and high energy density explosives, propellants, nanostructured and enhanced blast thermobaric explosives.


Wiadomości Chemiczne, 2008, 62, 1017.
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COMBRETASTATIN A-4 (CA-4) AND ITS ANALOGUES. SYNTHESIS AND BIOLOGICAL ACTIVITY

Krystyna Dzierzbicka*, Paweł Kubacka, Seweryna Renusz, Aleksander M. Kołodziejczyk

Katedra Chemii Organicznej, Wydział Chemiczny, Politechnika Gdańska, ul. G. Narutowicza 11/12, 80-952 Gdańsk
*e-mail: kd@chem.pg.gda.pl


This article described synthesis and biological activity of combretastatin A-4 (CA-4) and its analogues. Combretastatin A-4 (CA-4), a natural product isolated from the South African bush willow tree Combretum caffrum, binds to the colchicine binding site and inhibits the polymerization of microtubules. CA-4 exhibits potent cytotoxicity against a variety of human cancer cell lines including multidrug-resistant (MDR) cell lines [5-7]. The studies of structure-activity relationship (SAR) of CA-4 1 (Fig. 1) showed that 3,4,5-trimethoxy substitution on the A ring and the 4'-methoxy group on the B ring and the cis-olefin configuration are crucial for potent cytotoxicity, while the 3'-hydroxy group is optional [5-7]. A many of CA-4 analogues were synthesized where the double bond have been replaced by introduction of nonheterocyclic groups (e.g. ethers, olefins, ketones, sulfonates, sulfonamides, amide derivatives, amine, cyclopentanes) or heterocyclic groups containing five-membered rings (e.g. pyrazoles, thiazoles, triazoles, tetrazoles, oxazoles, furans, dioxolanes, thiophenes) and indoles [5, 7, 41, 56] (Fig. 9-12). Up to now, many CA-4 analogues and their biological activity have been extensively studied and three derivatives are currently in clinical trials: a water-soluble disodium phosphate derivative of CA-4 (CA-4P) 11c (Fig. 3); Oxi-4503, a water-soluble combretastatin A-1 (CA-1diP) 4a (Fig. 1); and AC7700 59e (Scheme 7) an aminocombretastatin prodrug developed in Japan in 1998 [5-10, 34].
 
Keywords: inhibitors of microtubule, combretastatin A-4, CA-4, synthesis, CA-4 analogues, antitumor activity, antimitotic activity.


Wiadomości Chemiczne, 2008, 62, 1037.
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ROLE OF HIPOXIA IN ADVANCES IN NEW ANTICANCER DIAGNOSTICS AND THERAPY

Katarzyna Błaszczak-Świątkiewicz*, Elżbieta Mikiciuk-Olasik

Zakład Chemii Farmaceutycznej i Analizy Leków, Uniwersytet Medyczny w Łodzi ul. Muszyńskiego 1, 90-151 Łódź
*e-mail: kasia@farm.pharm.am.lodz.pl


Contemporary radiopharmacy has played a significant role in the development of early oncological diagnostics. Such radiopharmaceutics as 18F-FMISO, 123I-IAZA, 99m Tc-HL-91 (Fig. 1b, 3b, 7b) are used in the state-of-the art scintigraphic and tomographic techniques, i.e. in the PET and SPECT methods to determine carcinoma progression and detect cells in hipoxic state already at the early stage of carcinoma development [2, 3]. These noninvasive and selective for hipoxic cells methods are characterized by excellent sensitivity and do not exert noxious effect on the remaining cells of the human organism [4, 5]. Characteristic hipoxia of solid tumors can be also identified with invasive methods, e.g. Elisa test or measurement of oxygen concentration in pathological cells using a microprobe. However, medical interference in the tissues affects the condition of the whole organism. Technical complications and low accuracy resulting from non-uniform hipoxia of the cancerous tissue environment render rear usage of these methods in clinical practice [3]. Diagnosis of hipoxia occurring in the carcinoma-changed cells permits treatment with drugs possessing bioreductive mechanism of activity. In this group of drugs, apart from nitro compounds and chinon derivatives, we can distinguish compounds with N-oxide structure [25]. Tripazamine (Fig. 11b) and banoxantrone (Fig. 11a) represent the latter group of compounds. These are so far the drugs with the best therapeutic parameters expressed by selectivity, efficiency of action and low general toxicity [25]. Also, gene therapy with the use of adenovirus vector coding nitroreductase seems to be a promising mode of treatment. This enzyme induces cytotoxic activity of nitro compounds, e.g. CB1954 (Fig. 10c), for cancerous cells with hypoxia [26].
 
Keywords: radiopharmaceutics, hipoxia, antitumor drugs.


Wiadomości Chemiczne, 2008, 62, 1065.
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PEPTIDE-OLIGONUCLEOTIDE CONJUGATES: SYNTHESIS AND APPLICATIONS

Renata Kaczmarek1, Ewa Radzikowska1, Janina Baraniak*1,2

1 Centrum Badań Molekularnych i Makromolekularnych Polskiej Akademii Nauk, Zakład Chemii Bioorganicznej, ul. Sienkiewicza 112, 90-362 Łódź
2 Wydział Matematyczno-Przyrodniczy, Instytut Chemii i Ochrony Środowiska, Akademia im. Jana Długosza, al. Armii Krajowej 13/15, 42-200 Częstochowa
*e-mail: baraniak@bio.cbmm.lodz.pl


Recently major advances have been made in the development of oligonucleotides as potential therapeutic agents [1-3]. However, a frequent limitation of their use is poor cellular uptake [5]. Among the many molecules that have been reported to enhance cell delivery of oligonucleotides there is a number of peptide carriers. They are preferably linked by covalent bond in many possible ways, resulting in a new class of compounds known as peptide-oligonucleotide conjugates (POCs) [6a, 9]. A variety of chemical linkages have been used to link the peptide and oligonucleotide fragments. A peptide can be conjugated either at the base-, 3'-, or 5'-position of the sugar unit or at the backbone of the oligonucleotide [10]. Similarly, the point of conjugation in a peptide can be either the C- or N-terminus or the side chain.

Two different strategies have been adopted for the synthesis of POCs: in-line solid-phase synthesis (divergent method) and fragment conjugation (convergent method) [11].

In divergent method, the peptide and oligonucleotide fragments are assembled on automatic synthesizers, sequentially on the same solid support, until the final step. In predominant cases, the peptides are assembled first by the Fmoc method, while the oligonucleotides are assembled next using the phosphoramidite method [12]. In-line synthesis could be most direct for preparing POCs, but finding the right combination of protecting groups is the key problem. The first step in preparation of POCs involves modification of solid supports with suitable linkers [10]. A number of monofunctionalized as well as bifunctionalized linkers were immobilized over solid supports through suitable spacers (Figure 1).

In the fragment conjugation, the peptide and oligonucleotide fragments are synthesized individually, cleaved from their solid supports, deprotected and purified, separately. Therefore, the most appropriate synthetic chemistry can be used for each component without concern for incompatibility. Both biopolimers are finally linked postsynthetically utilizing the reactive functional groups which are attached at the desired site of conjugation (Figure 4) [5]. If the postsynthetic conjugation is performed with one of the oligomers still joined to the solid phase, it is called the solid-phase fragment conjugation method. Alternatively, if the conjugation is effected after complete isolation and purification of the peptides and oligonucleotides, it is called fragment conjugation in the liquid phase [10].

Besides their potential use for therapeutic applications, POCs can serve as research tools, for example, as fluorescent probes [44] or PCR primers [25, 45]. With increased specificity and strength of target binding, POCs may be useful in diagnostic applications or as affinity purification reagents.
 
Keywords: peptide-oligonucleotide conjugates (POCs), in-line solid-phase synthesis, fragment conjugation, linkers, protecting groups, antisense strategy, therapeutic applications.


Wiadomości Chemiczne, 2008, 62, 1091.
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OKRUCHY VIII. Chemia a polityka

Ignacy Z. Siemion

Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław



Wiadomości Chemiczne, 2008, 62, 1115.
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T. Cukierda,   Last changes: