Wiadomości Chemiczne

Wiadomości Chemiczne, 1998, 52.

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  1. Asymmetric synthesis of a-amino acids
    Aneta Dąbrowska, Wiesław Wiczk

  2. Kinetics of fast biolmocular reactions studied by fluorescence quenching. III. Single photon counting
    Marek Sikorski

  3. Order in disorder or complexes of transition metal ions in oxide glasses and gels
    Andrzej M. Kłonkowski

  4. The effect of mercury and its compounds on the environment
    Teresa Lech

  5. Hydrogeles. Syntheses and applications
    Stanisław Glados, Mariusz Maciejewski

  6. Bunte salts - forgotten compounds
    Andrzej Orzeszko

  7. Notatki chaotyczne. XVII. De horrore novi
    Ignacy Siemion

  8. The research and the teaching activity of The Chemistry and Technology of Photographic Processes group of the Institute of Physical and Theoretical Chemistry
    Piotr Nowak

  9. The chemical industry of today in the light of environmental protection requirements
    Bogdan Burczyk

  10. Nickel enzymes
    Marek Wasilewski

  11. Applications of the Mitsunobu reaction in chemistry of amino acids
    Kazimierz Wiśniewski, Aleksandra S. Kołodziejczyk, Bogdan Falkiewicz

  12. Recent advances in selected aspects of spiran chemistry
    Janusz Jamrozik, Szymon Schab

  13. Potential and advantages with used of immunoenzymatic methods for analysis of antibiotic in food products
    Urszula Kucharska, Joanna Masłowska

  14. Notatki chaotyczne. XVIII. O chemii kombinatorycznej
    Ignacy Z. Siemion

  15. Photochemistry in researches of the old-time Polish scientists. Part II: Period 1900-1918
    Zdzisław Ruziewicz

  16. Science, chemistry, polymers, polymer nerworks
    Karel Duèek

  17. Kasimir Fakjans's quanticule theory
    Józef Hurwic

  18. Kinetics of the cleavage of aromatic anion radicals and of their formation
    Jan S. Jaworski

  19. Application of ion cyclotron resonance mass spectrometry to the study of proton-transfer reactions in the gas phase
    Ewa D. Raczyńska

  20. The mechanism and kinetics of formation and decay of XeCl* excimers in Xe-RCl systems
    Krzysztof Wojciechowski

  21. G protein-coupled receptors (GPCR): structure and receptor-bioligand interactions
    Jerzy Ciarkowski, Cezary Czaplewki, Rajmund Kaźmierkiewicz, Ewa Politowska

  22. The methods of synthesis of thio substituted pyrimidine bases
    Zdzisława Nowakowska, Elżbieta Wyrzykiewicz

  23. Wspomnienia o profesorze D. H. R. Bartonie
    Andrzej Sobkowiak

  24. Professor Jerzy Suszko: Remembering him and his scientific achievements
    Wiesław Zygmunt Antkowiak

  25. How kosmology explains fomation of chemical elements?
    Marek Ilczyszyn

  26. Search for the new drugs based on cisplatin
    Rafał Wysokiński

  27. The use of lipases in organic synthesis in nonaqueous media
    Zbigniew Chalecki, Jan Plenkiewicz

  28. Modelling of heterogeneous reactions of compounds in the atmosphere
    Valery Isidorov, Jadwiga Jaroszyńska

  29. Meaning of the term "speciation" in environmental chemistry
    Ryszard Świetlik

  30. "Extraction" utilizing cloud point phenomenon of surfactant solutions
    Jan Szymanowski

  31. Zdzisław Ruziewicz (1925-1997)
    Krzysztof Pigoń, Andrzej Olszowski

  32. Biogenic organohalogen compounds
    Przemysław Mastalerz

  33. The homoconjugation effect
    Anna Krawczyk

  34. Alice on the other side of a mirror
    Piotr Wojciechowski, Roman Gancarz

  35. Which properties of diatomic molecules can be determined from vibration-rotational spectra?
    Marcin Molski

  36. Chromatographic investigations. Part II.
    Alina Pyka

  37. Notatki chaotyczne. XIX. Przestroga Dedala
    Ignacy Siemion

  38. Structure of liquid water. Part I. Models of the water structure.
    Edward Dutkiewicz, Anna Jakubowska

  39. Structure of liquid water. Part II. Structure of Water in the Presence of Ions.
    Edward Dutkiewicz, Anna Jakubowska

  40. Kinetics of fast bimolecular reactions studied by fluorescence quenching. IV. Thioketones as model compounds
    Marek Sikorski, Andrzej Maciejewski, Marian Szymański

  41. Synthesis of six-member nitrogen heterocycles in heterodiene reactions. Krystyna Bogdanowicz-Szwed, Małgorzata Krasodomska

  42. The story of taxol : Ecstasy and torment
    Karol Kacprzak

  43. Low molecular inhibitors of plasmin
    Krystyna Midura-Nowaczek

  44. Notatki chaotyczne. XX. Filozofia a chemia
    Ignacy Siemion

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ASYMMETRIC SYNTHESIS OF a-AMINO ACIDS

Aneta Dąbrowska, Wiesław Wiczk, Leszek Łankiewicz

Zakład Chemii Peptydów, Wydział Chemii Uniwersytetu Gdańskiego, ul. J. Sobieskiego 18, 80-952 Gdańsk


a-Amino acids are among most important compounds in living organisms. Amino acids are not only constituents of peptides and proteins but they play an important role in many reactions in living cells. There are many excellent methods of the asymmetric synthesis of a-amino acids, but only some of them are versatile. In this work we have reviewed and presented the most versatile methods, giving the best chemical yield and optical purity of the final products.

One of the oldest and still useful synthetic route to racemic a-amino acids is Strecker's method [3], (Scheme 1). Modification of the method by Weinges et al. [8-11], (Scheme 2) allowed to obtain pure enantiomers of a-amino acids in high yields.

Next important group of the methods applies "glycine anion equivalent". In this group, "bislactim-ether method of Schollkopf et al. [13-21], (Scheme 3 and Tab. 1) has to be mentioned at first because of the high chemical yield of the transformation and optical purity of the final amino acid. The same type of methodology was employed by Seebach et al., in their method utilizing oxazolidinones or imidazolidinones [22-26], (Schemes 4, 5 and Tab. 2). Yield and enantiometric excess (ee) of the final amino acid in the method of Seebach et al., is very high (in most cases >80%). The only inconvenience is connected with drastic conditions of final hydrolysis. The similar, good results were also obtained in methods utilizing enolates obtained from oxazinones [29-31], (Schemes 6-8 and Tabs 3, 4).

Derivatives of the oxazynones were also applied as "glycine cation equivalent" in the method in which "the chiral cation" reacts with nucleophiles [32, 33], (Scheme 9 and Tab. 5) with the high chemical yield and ee of the final product.

The similar procedures were used in an alkylation of a chiral Schiff base. The best yield and optical purity of the final a-amino acid were obtained by Oppolzer et al. [35,36], who applied a derivative of glycine attached to bornane-10,2-sultam (the derivative of camphor), (Schemes 13,14).

The next group of synthetic procedures is based on a reaction of the ring openning of b-lactones obtained from serine [41-43], (Scheme 16) or threonine [44], and aziridines [45-48], (Scheme 17). A nucleophile attack on the b-carbon of the substrate gives amino acid with modified side chain. Despite of high yield and ee, a selection of possible nucleophiles is limited.

Another important methodology is called "electrophilic amination". In this procedure a chiral enolate obtained from N-acyl-oxazolidinone [50,52], (Schemes 18, 19) or N-acyl-sultam [51, 53], (Scheme 21) is aminated either by di-tert-butyl-azodicarboxylate (DBAD), [50, 51], trisyl azide [52], or 1-chloro-1-nitrozo-cyclohexane [53]. Yield of these reactions are high and ee exeeds 95%.

Contrary to the "electrophilic", a "nucleophilic amination" requires a "cation equivalent" obtained from a chiral N-acyl-derivatives [54-55]. The reaction usualy yields a desired product of good enantiometric quality. In most cases azide anion is a source of "nucleophilic amine equivalent" (Schemes 22 and 23). The chiral 2,3-epoxy-1-ols can be also applied in this methodology [57, 58], (Scheme 24).

Asymmetric catalytic hydrogenation of a dehydro derivatives of amino acids and peptides is the another valuable group of synthetic routes to the single enantiomer of the amino acid. There is possibility of heterogenous and homogenous catalysis involving insoluble catalysts [60, 61], (Schemes 27, 28) in medium of the reaction. The best results (yield nearly100% and ee equal or greate then 99%) were reported for the complexes of Rh with chiral phosphines ligands like BINAP or DIPAMP (Scheme 28), [67].

The last method reported in our review is based on usage of anzymes. The most widely used in this field are the following anzymes: acylases - catalizing stereoselective removal or synthesis of N-acyl derivatives [70], (Scheme 30) and proteases - catalyzing hydrolysis or synthesis of esters [71], (Scheme 31). Additionally, anzymatic methods give many cases both enantiomers at the same time.


Wiadomości Chemiczne, 1998, 52, 1.
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KINETICS OF FAST BIOMOLECULAR REACTIONS STUDIED BY FLUORESCENCE QUENCHING.
III. SINGLE PHOTON COUNTING

Marek Sikorski

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


The aim of this paper is to review the most widely used technique for studies of fast bimolecular reactions - Time Correlated Single Photon Counting Technique (TCSPCT). The TCSPCT has become one of the most powerful tools to investigate the fluorescence time behavior. The most prominent point of this method is the use of time-resolved fluorescence quenching as a method for studying diffusion-controlled reactions. The experimentally measured fluorescence decay D(t) is the convolution of the instrument response function E(t) and the fluorescence decay function I(t). The problem to solve is simply to determine the function I(t) when both D(t) and E(t) are known. In practice, however, the problem is highly complicated due to severe experimental distortions and correlations between adjusted parameters. In this paper we have attempted to evaluate the possibilities and limitations of TCSPCT under various conditions in determining the fluorescence quenching kinetics. To investigate fluorescence quenching using SCK theory it is essential to determine the values of R, D and k, because these parameters describe the rate coefficient of the reaction between the excited donor and the quencher - k(t). D represents the sum of the diffusion coefficients and R the sum of the radii of the donor in the electronic excited state and of the quencher respectively, and k, represents the specific rate constant. However, from the point of view of the fluorescence decay measurement, it is necessary to determine the values of t0, S, G0 and tr, where G0 is a scaling factor. In this paper particular emphasis is placed on the method enabling the determination of the numerical values of E(t) or the elimination of it from the procedure of data fitting according to SCK theory. Table 1 summarises details of experiment when the TCSPCT was employed to study kinetics of fast bimolecular reactions by observation of fluorescence quenching.


Wiadomości Chemiczne, 1998, 52, 43.
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ORDER IN DISORDER OR COMPLEXES OF TRANSITION METAL IONS IN OXIDE GLASSES AND GELS

Andrzej M. Kłonkowski

Wydział Chemii, Uniwersytet Gdański, ul. Sobieskiego 18, 80-952 Gdańsk


The most basic difference between crystalline and non-crystalline solids is that a long range order (LORO) in the distribution of atoms (ions) or molecules exists only in crystalline materials [1]. This is indicated by diffraction patterns: the ideal crystal (the first extreme case) shows reflectans whose location and intensity obey three Laue conditions. The second extreme case is an ideally random structure. Scattering of radiation is impossible in the case of an ideally homogenous medium. Any real substance, including non-crystalline materials, is inhomogenous regardless of its form or scale. Thus glasses can be thought of as assemblies of microcrystals (i.e. microcrystallites or paracrystals). Strain introduced due to lattice mismatch at grain boundaries, the presence of a disordered interfacial or matrix region, and defects such as dislocations, or stacking faults can be assumed to give rise to departures from periodicity at distances smaller than the average grain size [10]. In this sense glasses are interesting in the supramolecular science because they are intermediate objects in the way from random to organized matter [5].

The object of this article are such amorphous materials as inorganic oxide glasses with structural groups YO4 , where Y = Si, P, and organicallly modified silicate gels. Among the studied glasses are ones of the type: R2O-SiO2 and R2O-Al2O3-SiO2, where R represents alkali atom (Li to Cs) [23, 25, 27], as well as M(II)O-P2O5, where M(II) is an alkaline earth atom (Mg to Ba) [28, 29, 32, 33]. Undoped glasses and those doped with copper(II) ions were investigated. These metal ions have played the role of probes.

All the vitreous systems are classified according to their theoretical optical basicity Dcal proposed by Duffy and Ingram [34]. Thanks to this method one can methodically observe and sensibly interpret changes of real measures of basicity as molar refractivity of oxide ions Ro (see Figs. 9 and 10a), the so called Imagawa's basicity (Fig. 10b) and other physical and chemical properties of oxide glasses (Fig. 11). The studied glasses are also classified according to their bond nature (Fig. 6), taking into account their proximity to the onset of metallization [41]. Attention is also focused on the mixed alkali effect [22, 24].

A full understanding of the properties of colloids calls upon a wide range of physical and chemical ideas, while the multitude of colloidal systems presented to us in nature, and familiar in modern society, exhibits a dauting complexity. On the experimental side there is an ever-increasing emphasis on the application of modern physical techniques to colloidal problems. Colloid science is thus a truly interdisciplinary subject [3].

In the case of the xerogels there are described Cu(II) complexes existing on surface and in interior of the material [59-63]. Moreover, silica xerogels with immobilized supramolecular ligands show intensive luminescence (Fig. 17) which are effectively quenched by Cu(II) ions [64].


Wiadomości Chemiczne, 1998, 52, 57.
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THE EFFECT OF MERCURY AND ITS COMPOUDS ON THE ENVIRONMENT

Teresa Lech

Instytut Ekspertyz Sądowych, Westerplatte 9, 31-033 Kraków


In the paper, mercury and its compounds are generally discussed with respect to their circulation in nature, the role of the biological chain in penetration of mercury from the environment to the living organism and the toxicological findings in vegetables, animals and human beings after administration of mercury through different ways. The total amounts of mercury, present in the natural environment (air, water and soil) in several chemical forms, as a result of natural erosion of the earth's crust by wind and water far exceeds that caused by human activities; however, the amount of mercury, that exists in any one place (e.g. waste-sites, factories) as a result of human activities can be quite high. Redistribution and accumulation of mercury compounds (like lead and cadmium) as a result of industrialisation are the underlying causes of man's exposure to higher-than-natural amounts, and thus to their potential effects on human health.


Wiadomości Chemiczne, 1998, 52, 87.
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HYDROGELS. SYNTHESES AND APPLICATIONS

Stanisław Glados, Mariusz Maciejewski

P. P. H. U. "EKOCHEM" S. A., ul. Budowlana 4, 41-100 Siemianowice Śl.


Superabsorbent polymers (SAP), sometimes defined as water-absorbent polymers or hydrogels, can swell to absorb water, physiological fluids or saline solutions in amounts as high as 10-1000 times their own weight. This property has led to many practical applications of these hydrophilic, slightly crosslinked polymers and copolymers. This article presents a review of superabsorbent gel synthesis, focusing on acrylic superabsorbent, modified starch and cellulose absorbent polymers, maleic-anhydride copolymers and on some other selected systems.

Regarding practical applications a particular attention was given to uses in agriculture for improving water retention, medicine, biology and pharmacy, as well as in other miscellaneous fields of practice.


Wiadomości Chemiczne, 1998, 52, 101.
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BUNTE SALTS - FORGOTTEN COMPOUNDS

Andrzej Orzeszko1, Zygmunt Kazimierczuk2

1Katedra Chemii Ogólnej, SGGW w Warszawie, ul. Rakowiecka 26/30, 02-528 Warszawa.
2Zakład Biofizyki, Instytut Fizyki Doświadczalnej, Uniwersytet Warszawski, ul. Żwirki i Wigury 93, 02-089 Warszawa


This paper is devoted to organic thiosulfates, so called Bunte salts. On the occasion of the 150th anniversary of Hans Bunte`s birth (1848), the short biographical note was annexed. The main, historical method of synthesis of organic thiosulfate was described with some novel modifications [3-11]. In Figures 1 and 2 the general structure of Bunte salts and the mentioned reaction are shown respectively. Newer methods of synthesis like, for example, the addition of thiosulfate anion to alkenes or oxiranes are presented in Figs 3 and 5 [2,12,13,18,19].

In the next chapter some chemical properties of Bunte salts were described. Aqueous solutions of these compounds are unstable. In acid medium they hydrolyse to thiols, while in basic one to appropriate disulfides (Figs 6,7) [3,10, 22-26]. The reaction of dihalides with sodium thiosulfate leads to "double" Bunte salts carrying two thiosulfate end groups. It was found that in presence of NaOH or H2O2 these salts give appropriate polydisulfides [8, 9]. The scheme of this process is shown in Figure 11. It was found that anodic oxidation of Bunte salts leads also to di- and polydisulfides [7].

Usually, organic sulphur compounds shown strong biological activity. There are a few examples of biological studies on organic thiosulfates in the literature. The sodium ethylthiosulfate, originally prepared by Bunte [3], exhibits a striking synergistic effect with the bacteriostatic 2-mercaptobenzothiazole against Staphylococcus aureus and tubercle bacillus [43, 44]. Sodium salt of the aromatic 3-nitrophenylthiosulfate was reported to show strong preventive and curative activity against fowl coccidiosis [22]. Radioprotective properties of heterocyclic derivatives of thiosulfates were also investigated [48]. The chemical structure of Bunte salt anions carrying a long aliphatic chain suggests their amphiphilic character. It is known that amphiphility of numerous quaternary ammonium salts is responsible for their ability to damage cell membranes. We paid our attention to the relationship between the chemical structure and the antibacterial and fungicidal activity of a number of known and newly synthesised Bunte salts [7]. The results of this work are presented in Figure 13.
Many Bunte salts have excellent technical applications described in the patents cited [42-49].


Wiadomości Chemiczne, 1998, 52, 125.
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Notatki chaotyczne. XVII. DE HORRORE NOVI

Ignacy Z. Siemion

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



Wiadomości Chemiczne, 1998, 52, 137.
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THE RESEARCH AND TEACHING ACTIVITY OF THE CHEMISTRY AND TECHNOLOGY OF PHOTOGRAPHIC PROCESSES GROUP OF THE INSTITUTE OF PHYSICAL AND THEORETICAL CHEMISTRY

Piotr Nowak

Zakład Fototechniki Politechniki Wrocławskiej, Wybrzeże S. Wyspiańskiego 27, 50-370 Wrocław


The main scientific publications on chemistry and technology of light-sensitive materials, published by the Chemistry and Technology of Photographic Processes Group are listed. The main scientific and research activities performed in this unique group in Poland are presented. The technological achievements which have been applied in the Polish photochemical industry are also described. Additionally, the teaching achievements at the academic level of the Chemistry and Technology of Photographic Processes Group are described.


Wiadomości Chemiczne, 1998, 52, 157.
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THE CHEMICAL INDUSTRY OF TODAY IN THE LIGHT OF ENVIRONMENTAL PROTECTION REQUIREMENTS

Bogdan Burczyk

Zakład Chemii Organicznej, Wydział Chemii, Uniwersytet Jagielloński, ul. Ingardena 3, 30-060 Kraków


The consumption of manufactured chemical ( product ) has a manifold effect on resources and the environment. The chemical industry undertakes many activities to meet the requirements of environmental protection. Two from amongst the environmental management techniques, i.e., Life Cycle Assessment ( LCA ) [10] and Risk Assessment [13-15] are described and discussed in this paper. LCA studies the environmental aspects and potential impacts throughout a product's life from raw material acquisition through production, use, and disposal. Risk assessment is a formalized analysis of the adverse impact of some specific material, chemical, or procedure on humans and/or the environment. Examples of life cycle inventory (LCI which is part of LCA) for detergent alcohols production [12] and risk assessment for detergent surfactants use [21] are given.

Finally, some new types of chemodegradable surfactants are described. This term has been used since 1988 [22, 23] to describe "hydrolyzable" [24, 25], "cleavable" [26, 27], and "destructible" [27] surfactants that contain in their molecules at least one functional group susceptible to chemical reactions in aqueous environment (Scheme 1). In such reactions, surface active substances lose their chemical identity and, in many cases, surface properties as well. In this respect, chemodegradability is similar to primary biodegradability because a surface active substance is degraded in these processes to an extent that is environmentally acceptable [28]. This paper reports the synthesis of chemodegradable surfactants bearing in their molecules an ester or an acetal function, the latter beeing represented by cyclic 1,3-dioxolane or 1,3-dioxane structure (Scheme 3).


Wiadomości Chemiczne, 1998, 52, 175.
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NICKEL ENZYMES

Marek Wasilewski

Instytut Chemii Uniwersytetu Opolskiego, ul. Oleska 48, 45-951 Opole


Nickel is now well recognized as an essential ultra trace element for bacteria and plants, where five distinct types of Ni-containing enzymes have been identified. It is also considered to be essential for animals and humans, however its role in animal biochemistry is not well defined.

The article, containing 10 figures and 201 bibliographic positions, provides a current summary of the properties of known nickel enzymes, with emphasis on structure-function relations. In the begining the paper reviews accurrence of Ni in environment, and its biological importance. The relevant chemistry of nickel complexes has been shortly reviewed.

Nickel enzymes are particularly prominent in the metabolism of anaerobic bacteria. For example, the metabolism of methanogens involves methyl-CoM reductase, nickel hydrogenase, aceryl-CoA synthase, and carbon monoxide dehydrogenase. Important enzyme for many bacteria, fungi, and plants is urease. Urease catalyzes the hydrolysis of urea, to form ammonia and carbamate. It was the first enzyme ever to be crystallized (Sumner J. B., J.Biol. Chem., 1926, 69, 435; ibid., 1926, 70, 97). In 1975 Dixon and co-workers discovered that urease contain nickel at the active site (Dixon N. F. et al., J.Am. Chem. Soc., 1975, 97, 4131). Twenty years later the X-ray crystal structure of the urease from Klebsiella aerogenes has been determined (Jabri E. et al., Science, 1995, 268, 998). The enzyme is an (a b g3 trimer with each a-subunit having an (ab)3-barrel domain containing a binickel active site. A carbamylated lysine provides an oxygen ligand to each nickel, explaining why carbon dioxide is required for the activation of urease apoenzyme (Park I.S.,Hausinger R.P., Science, 1995, 267, 1156). In the paper the coordination geometry of nickel ions and the structure of active site, together with possible catalytic mechanism, are presented.

[NiFe]-hydrogenases catalyze the two electron redox chemistry of H2. Crystallographic data on the hydrogenase from Desulfovibrio gigas were presented (Volbeda et al., J. Am. Chem. Soc., 1996, 118, 12989), giving a new information on the structure and mode of action of its H2, activating place. The active center was found to contain a heterodinuclear active site composed of a Ni center bridged to an Fe center by cysteinate ligands, and by oxygen species, which is proposed to be signature of the inactive form of the enzyme. The iron atom binds three diatomic ligands, which are nonexchangeble triply bonded molecules (probably CO, CN- or NO). Based on the new structure possible modes of hydrogen binding and catalytic action of the active site are discussed.

Methyl-coenzyme M reductase (MCR) catalyzes the final stage of the reduction of carbon dioxide to methane in methanogenic bacteria. The terminal step involves prosthetic group, Factor 430 (F-430), which in the resting state is a nickel(II) tetrapyrrole. Studies of F-430 in the enzyme complex suggest a hexacoordinate, octahedral Ni(II) environment, with two oxygen axial ligands. The spectral data of the active form of MCR are characteristic for F-430 in the Ni(I) oxidation state (Goubeaud M. et al., Eur. J. Biochem., 1997, 243, 110), indicating that methyl-CoM reductase is activated when the enzyme-bound coenzyme F-430 is reduced to the Ni(I) state. The macrocycle can readily accomodate the structural changes, that accompany reduction Ni(II) to Ni(I).

Carbon monoxide dehydrogenase (CODH) catalyze the reversible oxidation of CO to CO2, at an active site, called the cluster C, composed of an [4Fe-4S] cube with pentacoordinate Fe (called FCII, linked to a Ni (Hu Z. et al., J. Am. Chem. Soc., 1996, 118, 830). Besides the enzymes that contain only CODH activity, there are the bifunctional enzymes that contain both CODH, and acetyl-CoA synthase (ACS) activity (Ragsdale S. W., Kumar M., Chem, Rev., 1996, 96, 2515). This enzyme catalyzes reaction of CO at two separate Ni-FeS clusters. Oxidation of CO to CO2 is catalyzed by cluster C, while incorporation of CO into acetyl-CoA occurs at cluster A. A model of catalysis is proposed.


Wiadomości Chemiczne, 1998, 52, 207.
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APPLICATIONS OF THE MITSUNOBU REACTION IN CHEMISTRY OF AMINO ACIDS

Kazimierz Wiśniewski1, Aleksandra S. Kołodziejczyk1, Bogdan Falkiewicz1,2

1Zakład Chemii Peptydów, Wydział Chemii, Uniwersytet Gdański, Sobieskiego 18, 80-952 Gdańsk
2Katedra Biotechnologii, Międzyuczelniany Wydział Biotechnologii Uniwersytetu Gdańskiego i Akademii Medycznej w Gdańsku, Kładki 24, 80-822 Gdańsk


The Mitsunobu reaction has been known since the late sixties. It is mediated by the redox system: triaryl- or trialkylphosphine/dialkyl azodicarboxylate and brings about the nucleophilic substitution of an alcoholic hydroxyl group by the conjugate base of an acidic reactant, with inversion of configuration at the alcohol carbon. The Mitsunobu reaction is widely used in organic chemistry and its mechanism (scheme 1) has been intensively studied (for review - see [2-5]). This article deals with the application of the reaction in chemistry of amino acids.

The reaction was proposed as an effective method of a-amino acid synthesis using hydroxy acids as substrates. As the amino group synthons phtalimide [10, 11], (Scheme 2), hydrazoic acid [14], (Scheme 5) or t-butyl-2(trimethylsilil)ethylsulphonylcarbamate [18], (Scheme 7) were used. The procedure using HN3 was profoundly improved by the introduction of a stable bis-pyridine complex of zinc oxide [16]. The use of phtalimide as an amino group precursor in Mitsunobu-type reaction was succesfully applied to the synthesis of 2-2H-labelled chiral glycine [13], (Scheme 4). In the model studies on the synthesis of 15N-labelled N-protected chiral amino acids Degerbeck et al. [17] found that the yield of the Mitsunobu conversion (Scheme 6) depends on the acidity of the NH function in the imidocarbonate or sulphonylcarbamate used.

The Mitsunobu reaction has also been applied to the synthesis of many unnatural or modified amino acids such as protected 2,3-diamino butyric acid [19], 3- or 4-mercaptoproline derivatives [20, 21], (Scheme 8), N5-acetyl-N5-hydroxy-L-ornitine [22], (Scheme 9) and a-N-hydroxyamino acids [23], (Scheme 10). Wojciechowska et al. [24] have reported the preparation of dehydroamino acids from protected serine and threonine derivatives under the intramolecular Mitsunobu dehydration condition (Scheme 11).

A general approach to the preparation of N-monoalkylated amino acids based on the Mitsunobu reaction has been developed [30] using N-tosylamino acid asters as acidic components of the reaction (Scheme 15). Since the removal of tosyl group is difficult, a modification of the N-alkylation procedure has recently been devised [32, 33].

The Mitsunobu reaction is also an excellent procedure for transforming hydroxy acids or hydroxy amino acids into esters whose subsequent hydrolysis leads to a stereoisomer of the initial compound with the inverted configuration at the carbinol centre and was very often used in this way [37, 38], (Scheme 8 and 17).

The Mitsunobu reaction provides also an interesting method of esterification in which an alcohol, not a carboxylic component, is activated. It was used to the synthesis of diphenylmethyl esters of N-trityl amino acids [43], to the attachment of a first amino acid to the polymer support [44] or to active ester synthesis [45], (Scheme 18).

The applications of the Mitsunobu reaction include also the preparation of many cyclic derivatives of amino acids such as b-lactams [51], (Scheme 20), aziridines [49, 54], (Schemes 19, 21) or b-lactons [60]. The last cyclic derivatives are valuable intermediates for the synthesis of b-substituted alanines (Scheme 22). b-Lactonization proceeds easily in case of serine derivatives whereas in threonine derivatives b-elimination is the dominant reaction [61], (Scheme 23).
The review deals also with the applications of the title reaction to the synthesis of peptide (polyamide) nucleic acids (PNA) [31, 39, 40, 68, 69, 70].


Wiadomości Chemiczne, 1998, 52, 243.
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RECENT ADVANCES IN SELECTED ASPECTS OF SPIRAN CHEMISTRY

Janusz Jamrozik, Szymon Schab

Instytut Technologii Organicznej i Tworzyw Sztucznych Politechniki Wrocławskiej, Wybrzeże St.Wyspiańskiego 27, 50-370 Wrocław


The chemistry of spiranes has been studied extensively from many points of view and has already been the subject of several papers. Generally the spiranes are not a new class of compound in the chemical sense, but they retain the chemical properties of their parent moieties. Much interest has been focused on the bonding character of the central spiro-atom. This review describes all aspects of spirane chemistry, that have been developed in the last few years: spiroconjugation, helical structure, conformational transmission, photochromism and biologically active spiranes.

When two perpendicular p systems are joined by a common tetrahedral atom, it is postulated that electronic delocalization will produce important and characteristic effects in the electronic spectrum [10, 11] and in chemical reactivity [14, 15]. This special case of homoconjugation has been called spiroconjugation (Scheme 1, 2). The presence of hypochromism suggest that the dominant conformation of spiranes is helical (Scheme 4, 5), [20-23]. The effect of conformational transmission in the series of new spirane systems was studied with the aid of 1H-NMR spectra (Scheme 7, 8), [36-38].

The photochromic behaviour of spiropyrans is based on the reversibility between the colourless "closed" spiropyran form and the coloured "open" merocyanine dye via heterolytic cleavage of the spiro oxygen-carbon bond (Scheme 9), [47, 48]. The spiropyrans and related compounds (spirooxazines) continue to arise a strong interest in various fields such as: non-silver high resolution photography [45], optical devices and holographic systems [46].

Many representatives of spiranes have a useful biological activity (Schemes 10,11), [49-55]. For example, 1,7-dioxaspiro[5.5]undecane is the major component of the sex pheromone of the olive fruit fly [56].

The purpose of this article is to show a "phenomenon" of the spiro-atom and to present the most representative examples of this approach.


Wiadomości Chemiczne, 1998, 52, 269.
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IMMUNOENZYMATIC METHODS FOR ANALYSIS OF ANTIBIOTIC IN FOOD PRODUCTS

Urszula Kucharska, Joanna Masłowska

Instytut Podstaw Chemii Żywności, Politechnika Łódzka, ul.B.Stefanowskiego 4/10; 90-924 Łódź


Antibiotics constitute a group of chemical compounds which arouse extreme excitements in people, in some cases great expectations and in others fear, anxiety and dismay. Such a situation is due to the observed effects of their action within the sphere of human life. Dosages of these chemicals may be regarded as indispensable and advantageous during medical treatment or as hazardous when overadosed. Antibiotics and antimicrobiological compounds constitute often toxic residuals in food. Due to a wide use of antibiotics as prophylactic measures in the breeding of animals which are the raw material base for the manufacture of food products, and the use of these compounds as food additives to prolong food stability and its life, there is a search going on to find out methods for determination and analysis of speciation of their trace quantities.

A valuable and large group of diagnostic methods with potential possibilities and significance in such analyses consists of immunometric methods [1-7]. Generally, these methods are based on selective reactions of complex formation between antibodies and antigens or haptenes which have developed a specific antibody in vertebrates organisms [1-4, 6]. The results of immunochemical reactions depend on many factors such as the type of sorbent, size of active surface, kind of marker, specificity of the formed bonds directly or indirectly affecting the kinetics and physic-chemistry of the serologic process (precipitation or agglutination) [2-7, 16-18]. The use of immunodiagnosis as a method of food analysis results in a considerable lowering of detection and determination thresholds of many substances [8-15].

Known immunological methods can be successfully used not only for the evaluation of antibodies [2-4, 13-18], hormones [19-23], autoantigens [24], but also for the determination of the nutritious components of food [25-28], proteins [29-43], vitamins [44, 45] as well as toxic bacterial, mycotic and mould residues [48-54], antibiotics [55-61], alkaloids [62, 63] and pesticides [64-70]. These methods can be utilized for analyses of final products as well as intermediates and raw materials, including the assessment of specified technological processes [71-79]. Their use make it possible to lower the detection and determination thresholds of the compound under analysis [80-84, 134-136].

Stored food products give rise to the formation of antibiotics under the influence of present or developing microflora [91-103]. The hitherto used methods for the determination of antibiotics include mainly various chromatographic procedures such as HPLC [101-110], GC [106, 111-115], P & TLC [116, 117], MS [118-123], or enzymatic methods. All these methods have been recognized as sensitive and satisfying the requirements of analysts [124-127]. However, their general utilization is relatively low due to expensive apparatus and equipment required. Therefore, in order to improve the sensitivity of determination and to reduce the costs of analyses, in the seventies, analysts started to use thin layer or column chromatography in combination with enzymatic or immunochemical reactions [128-133]. At present, penetrating research is going on in analytics to widely use proteins and not only enzymatic ones [1-7, 13, 16-18].

The properties of specific proteins can be used in analytics as agents which either directly or indirectly form selective complexes with the component of the compound under analysis. To provide good and effective monitoring of such reactions, one of the serologic reaction components is marked with isotopic tracer (115J, 3H, 57Co, 14C), fluorochromes (fluorescein isothiocyanate, rhodamine B isothiocyanate), enzymes (per-oxidase, alkaline phosphatase, glucose oxidase, urease) or colloidal gold [1-7, 134-136]. In addition, there is used an avidin-biotin system, with antibodies being marked with biotin and enzymes with avidin. Such an extension of biomolecule application increases the sensitivity of the antibody-antigen reaction by increasing the number of addition sites on biotinylated antibodies.

Among the immunometric methods, the highest effectiveness is shown by immunoenzymatic methods which may have a wide application due to the simplicity of their use. The effectiveness of such an analysis depends on the stage of sample preparation being dependent, in turn, on the immunometric method selected. Then, the processes of sample preparation for analysis are different accordingly. In most cases the sample preparation is based on extraction with organic solvents to remove homogenates of samples under analysis [61]. It is a significant point of any analysis to consider the procedures of speciation examination [137-140]. Thus, the choice of immunometric methods, as those with a high specificity, to that end seems to deserve recommendation.

The present paper reports the results of comparison of methods for the determination of antibiotics in food products of animal origin. The multidirectional comparison of properties, characteristics and values of various chromatographic methods: HPLC, GC, P&TLC and GC-MS with various immunimetric methods has clearly resulted in the benefit of immunoenzymatic methods. The best results in terms of technical development are obtained by the immunoenzymatic method ELISA [2-4, 7, 15-17, 71-74, 83, 84, 138-140]. This is due not only to its high specificity, detectability, sensitivity, but also to the short time of analysis, possibility of multiple repetitions under the same testing conditions, simple equipment and personnel requirements as well as low costs of determination.


Wiadomości Chemiczne, 1998, 52, 283.
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Notatki chaotyczne. XVIII. O CHEMII KOMBINATORYCZNEJ.

Ignacy Z. Siemion

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



Wiadomości Chemiczne, 1998, 52, 311.
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PHOTOCHEMISTRY IN RESEARCHES OF THE OLD-TIME POLISH SCIENTISTS. Part II: Period 1900-1918

Zdzisław Ruziewicz

ul. Zielonego Dębu 23, 51-621 Wrocław


The achievements of Polish scientists are presented against the back-ground of rapid development of photochemistry in the years 1900-1918. In organic photochemistry the photohalogenations were the topic of the main interest to many chemists at the universities of Lvov (Bronisław Radziszewski, Stanisław Opolski, Stanisław Tołłoczko) and Cracow (Julian Schramm's followers). The acenaphthylene photodimerization was discovered in Cracow by Karol Dziewoński in 1912 and the structure of two stereoisomers of the dimer thus obtained was proposed (1913). Contributions of Jan Bielecki, done in Paris (1910-1914), in collaboration with Victor Henri and René Wurmser, are mentioned. Extensive photokinetic studies carried out by Ludwik Bruner at the Jagiellonian University (1907-1913) and the precursory work of Józef Wierusz Kowalski on the phosphorescence spectra of organic molecules, performed in Fribourg (1907-1914), are discussed.


Wiadomości Chemiczne, 1998, 52, 325.
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SCIENCE, CHEMISTRY, POLYMERS, POLYMER NETWORKS

Karel Duèek

Instytut Chemii Makromolekularnej, Akademia Nauk Republiki Czeskiej, Heyrivského nám. 2, 162 06 Praha 6, Republika Czeska


Information note
       Profesor Karel Duèek was granted Doctorate Honoris Causa of Wrocław University of Technology during Wrocław Science Fair on November 14th, 1997. He is well known Czech scientist from the Institute of Macromolecular Chemistry, Czech Academy of Sciences in Prague. His contribution to the physicochemistry of polymers and in particular to the polymer network theory is overwhelming with more than 300 scientific papers and more than 3000 citations. Granting of Doctorate h.c. to Professor Duèek was initiated by the Institute of Organic and Polymer Technology and Department of Chemistry Scientific Council, which asked Prof. Andrzej Mulak - Chancellor of the Wrocław University of Technology to give this honor to widely recognized Czech scientist. Curriculum vitae and scientific achievements of Prof. Karel Duèek were presented by his promotor - Prof. Bożena N. Kolarz.

Wiadomości Chemiczne, 1998, 52, 353.
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KASIMIR FAJANS'S QUANTICULE THEORY

Józef Hurwic

Laboratoir de Diélectrochimie, Université de Provence, 3 pl. Victor-Hugo 13331 Marseille Cedex 03, France


In Fajans's interpretation a chemical molecule consists of quanticules and atomic cores (or atomic nuclei) electrostatically interacting and mutually polarizing each other. A quanticule is a precisely defined group of electrons whose character will be explained in many examples presented in this article.


Wiadomości Chemiczne, 1998, 52, 361.
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KINETICS OF THE CLEAVAGE OF AROMATIC ANION RADICALS AND OF THEIR FORMATION

Jan S. Jaworski

Wydział Chemii, Uniwersytet Warszawski, ul. Pasteura 1, 02-093 Warszawa


The theretical model proposed by Savéant [10] for the kinetics of the cleavage of aromatic anion radicals containing potential leaving groups and of their formation from aryl radicals and nucleophiles (essential steps of the SRN1 mechanism, shown in the Scheme 1) is presented. In that model the bond cleavage in anion radicals is viewed as an intramolecular dissociative one-electron transfer and the reverse reaction as an associative single-electron transfer. It leads to the quadratic relationship of the activation barrier DG¹ and the reaction driving force DG° (eq. (9)), similar to the classic equation of the Marcus theory for the outer-sphere electron transfer.

Experimental consequences of the Savéant model are also reviewed. They include the relationship between the cleavage rate constants k4 and the formal potentials of the radical anion formation RX/RX· - for the series of aryl chlorides and bromides in DMF (Fig. 3), solvent effects on the k4 values (Chapter 4), and the affect of substituents (Chapter 5). In particular, it was shown that the solvent effect on the thermodynamic contribution to the activation free-energy causes the increse of the cleavage rate constant for chloroanthracene radical anions with the solvent acceptor number (Fig. 4). However, for the dissociation of the C-Cl bond in radical anions of 4-chlorobenzophenone the solvent efect on the intrinsic activation barrier DG¹o, given by eqs (13) and (14) , is dominant and the intrinsic rate constant depends (Fig. 5) on the solvent Pekar factor (1/eop-1/es). The use of the Hammett equation to the cleavage rate constants is also discussed; it works in the case when the thermodynamic contribution to the activation barrier (eq. (12)) strongly depends on a substitutent (Fig. 6).

All the reviewed experimental data on the kinetics of the bond cleavage and the formation of radical anions can be rationalized on the basis of the Savéant model.


Wiadomości Chemiczne, 1998, 52, 367.
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APPLICATION OF ION CYCLOTRON RESONANCE MASS SPECTROMETRY TO THE STUDY OF PROTON-TRANSFER REACTIONS IN THE GAS PHASE

Ewa Daniela Raczyńska

Katedra Chemii Ogólnej, Szkoła Główna Gospodarstwa Wiejskiego, ul. Rakowiecka 26/30, 02-528 Warszawa


The principle of ion cyclotron resonance (ICR) reported in 1930 by Lawrence et al. [9] was firstly applied in mass spectrometry by Hipple, Sommer and Thomas in 1949 [26]. Their instrument has never been commercialized due to several problems with electronics and vacuum. Next instrument constructed by Wobschall et al. in the 1960s [27] had more chance. It was modified by Llewellyn [28] in cooperation with Baldeschwieler et al. [29] and become a commercial Varian mass spectrometer in the late 1960s. Its drift cell contained three separeted regions: ion source, analyser and ion collector. Important modofication in ICRMS was proposed by McIver in 1970 [10a, b]. He introduced a one region trapped-ion analyzer cell and a pulsed mode of operation.

First FT-ICR experiments were carried out by Comisarow and Marshall in 1974 [11]. They also applied a one region trapped-ion analyzer cell. The pulsed mode of operation in the one region cell was combined with Fourier transform techniques in first commercial Nicolet FT-ICR mass spectrometer. From this moment the FT-ICR mass spectrometry has become more attractive and more frequently used by chemists.

Since ions may be trapped for extended periods prior to detection in an ICR cell, both, ICR and FT-ICR mass spectrometry have been used to the study of gas-phase ion-molecule reactions [1-6]. First experimental gas-phase data of sufficient precision obtained by ICRMS became available from the 1970s for the proton-transfer reactions [2, 7, 8, 10, 41-43].

Relative acidity (DGA) or basicity (DGB) determinations were based on measurements of the equilibrium constants of proton exchange between two anions (A1- and A2-) or two bases (B1 and B2) [7, 8, 13a]. These reactions have been studied in order to determine intrinsic gas-phase acidities or basicities of compounds and to establish general gas-phase acidity/basicity scale. Presently there are a few thousands gas-phase data compiled in this scale by Lias et al. [40]. The upper limit of the GB scale is separated from the lower limit of the GA scale by ca 150 kJ/mol (Fig. 6), and thus spontaneous neutralization reactions between neutral acids and bases can not yet be observed in the gas phase.


Wiadomości Chemiczne, 1998, 52, 385.
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THE MECHANISM AND KINETICS OF FORMATION AND DECAY OF XeCl* EXCIMERS IN Xe-RCl SYSTEMS

Krzysztof Wojciechowski

Katedra Chemii Fizycznej, Instytut Chemii, Wyższa Szkoła Rolniczo-Pedagogiczna, ul. 3 Maja 54, 08-110 Siedlce


The mechanism and kinetics of decay of excited Xe(6s[3/2]1,2) atoms formed by irradiation of pure Xe by xenon resonance light (l=147 nm) is presented basing on Moutard et al. [9] reaction scheme (r. (2)-(8)). The mechanism of the decay of higher xenon exited states (6p, 6d, ...) produced by the electron beam is also presented (r. (9)-(14)). On this basis the mechanism and kinetics of energy transfer processes to RCl molecules in Xe-RCl system leading to XeCl(B,C) excimers is discussed. In particular the mechanism and kinetics of two- and three-body reactions of the lowest Xe(6s[3/2]1) state with chlorine donor molecules is presented. It has been shown that the two-body energy transfer reactions (19) occur with the rate constants in the range (3.5-7)·10-10cm3 s-1 [10, 11, 32, 33] (Tabs 1, 2). The yield of XeCl* excimers in these reactions is in the range from 0.02 for HCl up to 1.0 for Cl2 molecule (Tabs 1, 2). It has been shown also that at higher xenon pressures (above 20-50 Torr) with reaction (19) competes the fast three-body reaction (23), which also is a source of XeCl* excimers [10, 11]. The rate constants of reaction (23) for a few molecules are shown in Tab. 2. They are in the range (1-2) ·10-28cm6 s-1 and the yields of XeCl* excimers produced in these reactions are from 0.19 for CCl4 up to 0.5 for PCl3. It seems to be important in the construction of excimer lasers that in the case of HCl molecule, often used as a source of XeCl* excimers, the rate constant of three-body energy transfer reaction (23) is extremely high, k23=2.2 ·10-27cm6 s-1 [10] and the yield of XeCl* excimers in this process is equal to zero [10]. The XeCl* excimers decay via fluorescence with the maximum at l=308 nm, for B-X transition and l=340 nm for C-A transition. The typical spectrum of XeCl* excimers fluorescence is shown in Fig. 5. The fluorescence lifetime (r. (31), (32)) of XeCl* is equal to 11 and 120-130 ns, for B-X and C-A transitions, respectively [45, 58]. There is shown that the above values of XeCl* excimers lifetimes concern excimers at the lowest vibrational level (v=0) and they increase with v number (see Fig. 7) [43]. The mechanism and kinetics of collisional decay of highly vibrational XeCl(B,C) excimers with buffer gases (He, Ne, Ar, Kr) is also presented (r. (27)-(30)) [43]. The relaxed XeCl(B,C) excimers decay also in the two- and three-body quenching with Xe and RCl molecules. The mechanism and kinetics of above processes is shown (see reactions (35)-(37) and Tab. 4).


Wiadomości Chemiczne, 1998, 52, 405.
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G PROTEIN-COUPLED RECEPTORS (GPCR): STRUCTURE AND RECEPTOR-BIOLIGAND INTERACTIONS

Jerzy Ciarkowski1, Cezary Czaplewski1, Rajmund Kaźmierkiewicz1, Ewa Politowska1,2

1Wydział Chemii, Uniwersytet Gdański, ul. J. Sobieskiego 18, 80-952 Gdańsk; 2Centrum Informatyczne Trójmiejskiej Akademickiej Sieci Komputerowej, ul. Narutowicza 11/12, 80-952 Gdańsk


G protein-coupled receptors (GPCRs) form the largest superfamily, having over 1000 members, of integral membrane proteins sharing the following features: (i) All members form 7 hydrophobic a-helices of ~38 Å (25 amino acids, 7 turns) along a single chain. The consecutive helices pass the membrane forth and back, starting from the extracellular side, to form a heptahelical transmembrane domain. This arrangement implicates 6 interhelical loops, where of the even ones plus the N-terminus create the receptor's extracellular domain while the odd ones plus the C-terminus form its intracellular domain. (ii) All GPCRs are stimulated by extracellular signal of miscellaneous character. (iii) Stimulated GPCRs pass the extracellular signal via their transmembrane and intracellular domains to the cytosolic peripheral heterotrimeric GTP/GDP-binding proteins (G proteins), mediating the signal's further transduction to various cellular second messenger systems. A current status of structural studies on GPCRs, consisting of low ~7.5 < Å resolution experimental structures and suplementary molecular modelling, is presented. Subsequently, some results of author's own work on modelling essential interactions between the V2 vasopressin renal receptor (V2R) and its agonists [Arg8]Vasopressin (AVP), [D-Arg8]Vasopressin (DAVP), and both the peptide desGly9-[Mca1, D-Ile2, Ile4]AVP and the nonpeptide antagonist OPC-31260, are discussed. Finally, perpectives for future developments are outlined.


Wiadomości Chemiczne, 1998, 52, 431.
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THE METHODS OF SYNTHESIS OF THIO SUBSTITUTED PYRIMIDINE BASES

Zdzisława Nowakowska, Elżbieta Wyrzykiewicz

Zakład Spektrometrii Masowej Związków Organicznych, Wydziała Chamii, Uniwersytet im. A. Mickiewicza, ul. Grunwaldzka 6, 60-780 Poznań


Utracil thio-derivatives have become to play increasingly important roles in biology and medicine. Numerous sulphur-substituted pyrimidines have found applications as clinically useful drugs. Thiouracils have recently been the subject of considerable interest as they inhibit hyperthyroidism in man [1, 2], have been isolated from E. coli tRNA [3], and ihibit virus [4] and bacterial growth [5] by causing alterations [7] in protein synthesis. Thiouracils are also of interest because of mutagenic [7], anticancer and antithyroid activity [8], kidney stone formation inhibition [9] and antidote properties for mercury poisoning. Two of them, 2-thiouracil and 6-propyl-2-thiouracil, exhibit marked affinities for melanin-producing tissue in vitro and a similar affinity in vivo, where they presumably act as false precursors for melanin [10, 11]. Boron-containing derivatives of thiouracils [12-14] containing a dihydroxyboryl (or 1-o-carboranylalkyl) group in the 5-position are very important because of their potential applications for BNCT. Human immunodeficiency virus type 1 (HIV-1) is the causative agent of acquired immunodeficiency syndrome (AIDS), which is one of the world's most serious health problems. Since the discovery of the acydic 6-substitited uridine derivative 1-[(2-hydroxyethoxy)methyl]-6-(phenythio)-thymine (HEPT) as a novel lead for specific anti-HIV-1 agents [15], a number of HEPT analogs have been synthesized to increse its potency [16-18]. The studies of the structure-activity relationships of HEPT analogs indicated that replecement of the 2-oxo function with a thione function potentiated their ati-HIV-1 activity [16, 19, 20].

Therefore the synthesis of thio-substituted pyrimidine bases and their derivatives appears to be a challenge for organic chemists. The methods of preparation of these compounds have been reviewed.


Wiadomości Chemiczne, 1998, 52, 449.
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Wspomnienia o profesorze D. H. R. Bartonie

Andrzej Sobkowiak


Wiadomości Chemiczne, 1998, 52, 467.
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Professor Jerzy Suszko: Remembering Him and His Scientific Achievements

Wiesław Zygmunt Antkowiak

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


A quarter of a century has already passed since the most distinguished Polish pioneer in both natural products chemistry and stereochemistry, the scientist meritorious for chemistry education, Professor Jerzy Suszko, passed away. He was born in Silesia near Teschen in 1889 and studied at the Polytechnic of Prague where he finished his Ph.D. thesis under the auspices of Paul Rabe at the age of 24. After World War I he took on research work at the Jagiellonian University in Cracow collaborating with Karol Dziewoński at the beginning. Next, after passing a habilitation examination and spending three years at the University of Lvov, he moved to Poznań, where he spent the second half of his life, working as a professor and the Head of the Organic Chemistry Department of the University of Poznań. Furthermore, he was to become the Head of the Laboratory of Alkaloids of the Institute of Organic Chemistry of the Polish Academy of Sciences. He also held some highly responsible offices at the University, the most important being a Rector of the University and a Dean of the Mathematical and Natural Science Faculty for a few years.

The main scientific achievements of Professor Jerzy Suszko were concerned with the chemistry of physiologically active natural products and with the spatial structure of organic molecules. From among the natural products, the alkaloids and especially those of cinchona bark were the most intensively studied mainly because of their pharmacological properties. His synthetic and structural studies analysed all the most reactive and stereochemically important fragments of the molecules of quinine and related alkaloids. This resulted in an elaboration of syntheses allowing interconversions both between the analogues differing by the kind of substituent in the quinoline moiety as well as the corresponding stereoisomers. Further significant achievements in the same field comprised, among others, the elaboration of a convenient method of a reverse conversion of quinotoxine (the product of an acid treatment of quinine but also occurring as the key intermediate in the quinine synthesis) and related toxins to the natural cinchona alkaloids, the determination of the pattern of rearrangement within the vicinal amino-alcohol fragment, and the discoveries in the chemistry of derivatives with a modified vinyl side chain, especially those being intramolecular ethers. The structure and conversion studies of other alkaloids concerned those occurring in the genera Papaver (codeine and rheadine), Lupinus and Cortinarius. At the beginning of the thirties, J. Suszko proposed a new method of determining the molecular symmetry, especially in the case of fused-ring polycyclic aromatic hydrocarbons. This method was next verified mainly on naphthalene molecules and was based on the binding of two identical chiral substituents to the ring system in different positions followed by an analysis of the resulting stereochemical mixture. Other stereochemical studies concerning stereocontrolled syntheses, conformation stability and configuration determination were carried out on various cyclic aliphatic hydrocarbons, including bornane derivatives.

Professor Jerzy Suszko educated a great number of graduated students both in chemistry and pharmacy. From about forty people who got their Ph.D. degrees under his scientific supervision many later reached the highest levels in their scientific careers. He was a founding member of the Polish Chemical Society and was very much engaged in its activities during his whole life. He served in some responsible offices therein, including the President of the Society. He was also a member of several foreign scientific societies, including the American Chemical Society.


Wiadomości Chemiczne, 1998, 52, 473.
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HOW COSMOLOGY EXPLAINS FORMATION OF CHEMICAL ELEMENTS ?

Marek Ilczyszyn

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


Cosmology is presented as a branch of science dealing with the universe. The most important achievement in this field is Big Bang theory accounting for the formation of the universe by an explosion 10 - 25 billion years ego. This event was followed by different processes schematically divided into "Planck", "hadron", "lepton", "radiation" and "galaxy" era (table 1).

Universal abundance of elements is presented as a relation between logarithm of the elements (or isobars) abundance in the solar system and the atomic (or mass) numbers (fig. 1 and 2). These relations are treated as a records of the Universe evolution. Four groups of the nucleosynthesis are presented according to this idea (table 2): (1) primary reactions at the beginning of the Universe; (2) "burning" of light elements inside stars; (3) neutron capture inside stars; (4) photonuclear reactions inside strongly heated-up stars, natural disintegration of heavy elements inside and outside the stars, breaking of heavy elements in the interstellar space.

Light chemical elements - from hydrogen to lithium - were created during the first minutes after the Big Bang by primary nucleosynthesis processes (reactions 1 - 7). This mechanism is responsible for very high abundance of hydrogen (~ 90% of all atoms in the Universe) and helium (~ 9%). Heavy elements are produced up to now inside stars.

Special attention is paid to description of different stages and ways of star evolution (fig. 3) and to relations of this processes to the nucleosynthesis inside stars (reactions 8 - 38). These processes strongly depend on the beginning mass of the star. Stars similar to the sun are responsible for formation of carbon and oxygen only. In the bigger ones the elements up to the iron group can be formed. In the case of the largest ones supernova phenomenon is possible: the star that has exhausted its nuclear fuel, collapse into a superdense state, and explode with a final burst of enormous energy. This is responsible for reactions from the group (4).


Wiadomości Chemiczne, 1998, 52, 511.
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SEARCH FOR THE NEW DRUGS BASED ON CISPLATIN

Rafał Wysokiński

Instytut Chemii Nieorganicznej i Metalurgii Pierwiastków Rzadkich, Politechnika Wrocławska, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław


Cancer therapy is one of most the challenging tasks for medicine at the end of this century. The subject of discussion in this paper is cisplatin which about thirty years ago has awaked a hope for an effective treatment of cancer. The following problems have been reviewed: the effect of various substituents on the biological activity of the compounds: cis-PtAm2X2 (where Am is ammine or amine and X is an anionic group), the mechanism of action of cisplatin and the structures of its coordination compounds with DNA. The side effects of cisplatin therapy, in particular its nefrotoxicity, and the attempts to establish the structure-activity relationship have also been discussed. The second and third generation of platinum-based drugs are presented, including the cisplatin drugs which are joint with some biologically active compounds. They act as the vectors delivering the drug directly to the cancerous cells, hereby decreasing toxicity of these drugs.


Wiadomości Chemiczne, 1998, 52, 529.
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The Use of Lipases in Organic Synthesis in Nonaqueous Media

Zbigniew Chalecki, Jan Plenkiewicz

Zakład Technologii i Biotechnologii Środków Leczniczych, Wydział Chemiczny, Politechnika Warszawska, ul. Koszykowa 75, 00-662 Warszawa


In nature enzymatic reactions are conducted in aqueous media. However, for organic synthesis purposes nonaqueous conditions such as organic solvents are more suitable regarding reagents stability and reaction equilibrium. Rapidly increasing number of enzyme-catalysed processes shows great possibility of this domain of chemistry. This review presents methods that have been used in lipase-catalysed esterifications and transesterifications in nonaqueous media. We show many examples of resolution of racemic alcohols and acids using different lipases in different reaction conditions. We also present a few examples of high regioselective properties of lipases. There are described general principles that govern lipase-catalysed reactions and some historical review of development of biocatalysis in organic synthesis. We hope that this review will be helpful for the investigators and the students in solving their problems in enzymatic synthesis.


Wiadomości Chemiczne, 1998, 52, 545.
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Modelling of heterogeneous reactions of organic compounds in the atmosphere

Valery Isidorov, Jadwiga Jaroszyńska

Instytut Chemii, Uniwersytet w Białymstoku, Al. Piłsudskiego 11/4, 15-443 Białystok


Any organic substances emitted from various sources into the oxygen-containing atmosphere are subjected to oxidation in sunlight-initiated reactions. The role of various processes in the sinks is different and inconstant because it depends not only on the physico-chemical properties of specific compounds but also on varying environmental conditions, solar radiation level, the content of anthropogenic pollutants and dust in the atmosphere, aerosol particles composition, etc. [1-3].

A fundamental property of the Earth's atmosphere is its heterogeneity. Billions of tons of continuosly renewed finely dispersed material with tremendous surface and excess free energy are annually emitted into it. Aerosol particles formed during weathering of the Earth's crust mainly consist of minerals based on silica (pyroxene, epidote, mica, quartz, etc.) as well as apatite, magnetite, ilmenite, etc. [13-15]. The particles of NaCl and KCl in the sea aerosol contain as inclusion in the crystalline lattice the atoms of many metals (Fe, Mn, Cr, Cu, Ti, Zn, etc.) [9]. This composition of the main components of natural aerosol ensures the appearance of impurity conductivity upon irradiation with light in the near UV or even in the visible spectral regions (Tabl. 3).

As a result of irradiation, various active centers (free radicals and ions) are formed on the particles, thus ensuring the possibility of photochemosorption of volatile components [16-21]. Therefore, there is no doubt that the surface of solid particles of atmospheric aerosol should serve as an arena on which various chemical transformations with the participation of sorbed components take place (Tab. 5).

The results of laboratory investigations of the oxidation of isoprene, monoterpenes [43-45, 47], aromatic hydrocarbons [36, 44-46, 48, 50-52] and halocarbons [27, 28, 30] on particles of metal oxides, desert sand, volcanic ash, sea salt, and calcium carbonate are reported. The only gaseous oxidation product was CO2, however, a broad spectrum of intermediates is detected on the particle surface. The values of rate constants for heterogeneous oxidation of different organic compounds indicate that these reactions can compete with gas-phase oxidation and, hence, deserve attention as a possible sink of Corg in the atmosphere [48, 58-60].


Wiadomości Chemiczne, 1998, 52, 569.
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MEANING OF THE TERM "SPECIATION" IN ENVIRONMENTAL CHEMISTRY

Ryszard Świetlik

Katedra Ochrony Środowiska, Politechnika Radomska, ul. Chrobrego 27, 26-600, Radom


Speciation is a typical example of a term that has various meanings. Studying scientific environmental chemistry literature published in English we can come across different meanings of the term. The terms specjacja (speciation) and analiza specjacyjna (speciation analysis) have been gradually appearing in the Polish scientific and technical literature for some time. The development of precise definitions of the two terms will help us avoid terminological confusion.


Wiadomości Chemiczne, 1998, 52, 587.
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"EXTRACTION" UTILIZING CLOUD POINT PHENOMENON OF SURFACTANT SOLUTIONS

Jan Szymanowski

Instytut Technologii i Inżynierii Chemicznej Politechniki Poznańskiej, pl. M. Skłodowskiej-Curie 2, 60-965 Poznań


Nonionic surfactants containing a polyoxyethylene chain 1 and 2 dissolve well in aqueous solutions due to the hydration of the hydrophilic chains. All parameters, e.g. temperature and electrolyte content, which affect the hydration change the solubility of nonionic surfactants in water. As a result, clouding of surfactant solutions is observed after heating them. The process is reversible and nonionic surfactants dissolve after cooling. Aqueous solutions of zwitterionic surfactants (3 and 4) also exhibit the cloud point phenomenon but in this case after cooling.

The cloud point temperature depends on several parameters, including the hydrophobicity and polydispersity of surfactants, the presence of additional organic compounds, e.g. alcohols, fatty acids, etc., and type and content of electrolytes. Therefore, the cloud point can be easily modified to cause the clouding at a temperature suitable for a separation process. The phases can be then separated, e.g. by centrifugation. However, only the knowledge of the surfactant-water phase diagrams (Figs. 1 and 2) permits the design of optimal conditions at which the surfactant-rich-phase is in equilibrium with almost pure water. Aqueous solutions of some b-cyclodextrine derivatives (Fig. 3) also exhibit the clouding phenomenon caused, however, by crystallisation.

Nonionic surfactants dissolved in organic solvents complex small amounts of ion pairs. As a result, they are considered as open analogs of crown ethers. Aqueous solutions containing surfactants at concentrations above the critical micelle concentration adsorb various organic and inorganic substances, including chelating agents and chelates. Ions can be also adsorbed by charged micelles. The spherical micelles of nonionic surfactants (Fig. 4) can be thus considered as dynamic analogs of crown ethers.

Typical hydrophobic extractants/chelating agents used in hydrometallurgical processes are exceedingly large and scarcely soluble in aqueous solutions, including micellar solutions, to obtain high enough extractant concentrations. Because of that, hydrophilic complexing agents such as oxine, PAP, PAMP, etc. are used. Special reagents exhibiting both amphiphilic and chelating properties (5 and 6) can be also used. In this case they act simultaneously as surfactants and chelating agents.

The distributions coefficients of chelating agents (Tables 1 and 2) and their metal complexes (Table 3) between the surfactant-rich phase and the aqueous phase are comparable to those observed in classical extraction systems. These are, however, lower in comparison to those obtained for hydrophobic industrial extractants.

The recovery of metal ions from diluted aqueous solutions can be near 100% (Table 4). The system is also useful to recover various organic substances from aqueous solutions (Table 5) and from contaminated soil (Table 6). The technique has found already application for sample preconcentration, recovery of toxic substances from solutions and soils and for separation of expensive biological materials.


Wiadomości Chemiczne, 1998, 52, 597.
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ZDZISŁAW RUZIEWICZ (1925-1997)

Krzysztof Pigoń1, Andrzej Olszowski2

1Plac Grunwaldzki 17 m. 42, 50-378 Wrocław 2Instytut Chemii Fizycznej i Teoretycznej Politechniki Wrocławskiej Wyb. Wyspiańskiego 27, 50-370 Wrocław



Wiadomości Chemiczne, 1998, 52, 617.
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BIOGENIC ORGANOHALOGEN COMPOUNDS

Przemysław Mastalerz

ul. Gliniana 23/17, 50-525 Wrocław


For proper assesment and understanding of the environmental impact of industrial organohalogen compounds it is necessary to consider also the emision of these compounds from natural sources. This, however, is usually omitted from discussions on environment pollution by chemical industry although there is ample evidence that the scale of synthesis of organohalogens by bacteria, plants and animals is much larger than their production by human endeavour.

Recent developments demonstrate that all forms of life synthesize organohalogen compounds. The total number of biogenic compounds containing fluorine, chlorine, bromine or iodine which have been isolated from microorganisms, plants and animals as of 1997 approaches three thousands and is growing rapidly. The halogens appear in all conceivable types of chemical structures from simple halogenated alkanes to policyclic molecules of astounding comlexity. This review presents a selection of over one hundred structures ranging from methyl chloride to prymnesin, a molecule containing three chlorine atoms attached to a polyunsaturated, continuous chain of 90 carbon atoms twisting its way through thirteen tetrahydropyran and one oxacycloheptane ring. The main focus is on chemical structures but there are provided also the sources of origin of individual compounds and brief comments on biological activity.


Wiadomości Chemiczne, 1998, 52, 643.
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THE HOMOCONJUGATIO EFFECT

Hanna Krawczyk

Wydział Chemiczny Politechniki Warszawskiej, ul. Noakowskiego 3, 00-664 Warszawa


The present paper concerns the homoconjugation effect in different molecules, particularly in the norbornadiene system. Information on the discovery and nature of the homoconjugation phenomenon [6, 7], classification of structures in which its presence has been found [32-56] as well as some of the most important methods, like UV [9, 65, 66], ETS [26], 13C NMR [82-96], ab initio [8, 17, 98, 99], used for examining this phenomenon are discussed in this work.


Wiadomości Chemiczne, 1998, 52, 673.
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ALICE ON THE OTHER SIDE OF A MIRROR

Piotr Wojciechowski1, Roman Gancarz2

1Instytut Inżynierii Chemicznej i Urządzeń Cieplnych Politechniki Wrocławskiej ul. Norwida 4/6, 50-373 Wrocław 2Instytut Chemii Organicznej, Biochemii i Biotechnologii Politechniki Wrocławskiej ul. Wybrzeże Wyspiańskiego 27, 50-370 Wrocław


It is well know that living organisms show strong enantiomeric selectivity in their molecular level. The enantiomorphic discrimination is sometimes manifested in the shape of the animal or plant. It was Paster who in 1857 discovered that the chemistry of life had a preferred handedness. "Life is manifested to us as a function of the dyssymetry of the universe" he wrote. Pasteris work was carried out well before the recognition of the quadrivalence of the carbon by Kekule and Couper (1858). He did far more that simply discover the underlying theory of molecular asymmetry, he foresaw most of the consequences of that theory, he understood the principle of a transference of the asymmetric property from one set of molecules to another. Finally he clearly understood the biological implications of the discovery of asymmetry. The theory of organic stereochemistry has been established independently by van't Hoff and Le Bel in 1874.

Now, very frequently we have the question why is no "mirror life". Would not biochemistry like ours with every configuration inverted be just as good? Was our way better or lucky? In 1957 it was found that mirror symmetry is broken on the subatomic level. Some elementary particles, like neutrino, exist only as a left-handed object. Thus, in fact, there are no exact enantiomers in our world. They are rather diastereoisomers of different energy. Thus, our mirror images friends living on the other side of the looking glass, with all the biological molecules with opposite configurations would not be as perfect as we are.


Wiadomości Chemiczne, 1998, 52, 699.
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WHICH PROPERTIES OF DIATOMIC MOLECULES CAN BE DETERMINED FROM VIBRATION-ROTATIONAL SPECTRA?

Marcin Molski

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


Highly resolved vibration-rotational spectra of diatomic molecules are sources of important information about the internal structure and physical properties of diatomic molecules, including mechanical, extra-mechanical and electromagnetic properties. The mechanical effects are considered in terms of Born-Oppenheimer internuclear potential whereas extra mechanical properties constitute adiabatic and nonadiabatic effects. Electromagnetic properties of a molecule include dipole moment, electric polarity and rotational g-factor connected with molecular magnetisability. In the review we discuss a possibility to determine from the spectra not only the aforementioned properties but also a molecular susceptibility to rotational deformation caused by the centrifugal force. The theoretical considerations are illustrated by the analysis of highly resolved spectrum of the seven isotopomers of GeS including 74Ge32S, 70Ge32S, 76Ge32S, 73Ge32S, 72Ge32S, 74Ge33S and 74Ge34S, allowing us to determine the dipole moment, electric polarity and the rotational g-factor of this molecule.


Wiadomości Chemiczne, 1998, 52, 713.
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CHROMATOGRAPHIC INVESTIGATIONS. PART II.

Alina Pyka

Katedra i Zakład Chemii Ogólnej i Analitycznej Wydziału Farmaceutycznego Śląskiej Akademii Medycznej w Katowicach 41-200 Sosnowiec, ul Jagiellońska 4


The prediction of physicochemical and toxicological properties of organic compounds with selected topological indices have been reviewed in monographs [1-14] and in dedicated articles [15-40]. The first topological indices used to prediction of selected physicochemical properties (the boiling point, heat of formation, heat of vaporozation, molar volume, molar refraction) were Wiener index, polarity number [41-45] and Platt's index [46]. The Wiener index has been continuously modified [47-64].

In recent years topological indices have come prominently to the fore on several different fronts. The prime reason for the wide publicity accorded to these indices has been the remarkable ability to correlate and predict the properties of a vast range of molecular species. Topological indices based on the adjacency matrix, on the distance matrix and on information theory were applicable to the calculation of many physicochemical properties [2, 8, 13-15, 17-19, 21, 28, 30-33, 39, 41-46, 65-199] and to the evaluation of biological and of toxicological properties [1, 2, 8, 17, 19, 21-25, 27, 28, 33, 34, 36, 37, 70, 110, 105, 111, 116, 121, 122, 131, 144, 148, 152, 162, 165, 166, 168, 171, 176, 200-286] of organic compounds. The procedure for calculating the topological indices is illustrated in this work by the calculation of the topological indices based on the adjacency matrix (the Gutman index (M1) [8, 9, 26, 287, 288], eq.(1); the Randić connectivity indices (oc, 1c, 2c,ocn, 1cn, 2cv) [ 1, 2, 8, 9, 26, 288-290], eqs. (2),(3)); on the distance matrix (the Wiener index (W) [8, 9, 26, 41-45, 288, 291], eq.(4), Tab.1; the Pyka indices (A, oB, 1B, 2B) [288, 295, 296], eqs.(5)-(8); the Balaban index (IB) [9, 26, 288, 292-294], eq.(9); the Schultz Molecular Topological Index (MTI) [9, 88, 288], eq.(10)) for pentamethylenediamine. It should be remarked that none of these topological indices yet described differentiates between d and l isomers. The procedure for calculating the optical topological index (Iopt) for d and l isomers is illustrated in this work by the calculation of Iopt for d- and l- alanine [288, 298, 299], eq.(11), fig.1. Applications of these topological indices for the correlation analysis are discussed.

The TLC [2, 14, 15, 17, 98, 118, 134-138, 140, 144, 164, 165, 167, 183, 186, 267-270, 295-297, 303-321], the HPLC [15-17, 137-139, 150, 152, 162, 164, 165, 256, 300, 302, 309, 310, 315, 320, 323-356], and the GC [2, 15, 17, 25, 28, 66, 87, 98, 125, 165, 167, 187, 310, 312, 317, 320, 339, 357-424] retention parameters of different organic compounds were calculated using the equations with the topological indices. As examples, selected correlation equations for calculation retention parameters in TLC (eqs.(12)-(20)), in HPLC (eqs.(23)-(31)), and in GC (eqs.(32)-(43), and eqs.(45)-(48)) were shown in this work.

Definitions of the three-dimensional Wiener number - 3W [9, 47, 67, 425-427], eq. (44) and the mean square distance topological indices of the s-th order - D (s) [26, 394], eq. (49) were presented.


Wiadomości Chemiczne, 1998, 52, 727.
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Notatki chaotyczne. XIX. PRZESTROGA DEDALA.

Ignacy Z. Siemion

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



Wiadomości Chemiczne, 1998, 52, 755.
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STRUCTURE OF LIQUID WATER. PART I. MODELS OF THE WATER STRUCTURE.

Edward Dutkiewicz, Anna Jakubowska

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


Without doubt, water is the most studied system in chemistry. Despite this fact, water is still far from being satisfactorily described on the molecular level and continues to fascinate new generations of chemists [1]. This situation reflects the difficulty of providing a structural description that accounts for the dynamic behavior of the H bonding ability of water, i. e., the ability of water molecules to form different structures. The aim of this work was to present different models describing: 1) a water molecule; 2) hydrogen-bond networks; 3) the water structure.

A first model of a water molecule was done by Bjerrum [7]. Various modifications of this model were proposed later. Water models proposed by Ben-Naim-Stillinger (BNS model) [8] and Stillinger-Rahman (ST2 model) [9] are tipical ones among the four-point charge models. The model proposed by Rowlinson [10] is a modified four-point charge model. Matsuoka-Clementi-Yoshimine's model [11] is a three-point charge model of the water molecule. Jorgensen's model [3] is also described in this work. Besides these rigid models of a water molecule, flexible models have also been introduced. Typical ones are the central force (CF) model [13] and its modifications proposed by Bopp-Jancsó-Heinzinger (BJH) [14].

We also present different models describing hydrogen-bond networks: model based on polygons [33] (rys. 1), bond percolation models [34, 39] and lattice models (square water - rys. 2 - [37], simplified square water [38], brick water [38]).

Models describing the water structure may be divided into two main classes: mixture (a fluid composed of molecular clusters of various sizes) and continuum models [40, 41]. Continuum models are not sufficient to explain the unusual behavior of H2O and D2O.

Water can also appear to be a macroscopic, space-filling gel-like network [34, 35, 42, 43]. This structural picture of water combines ideas of continuum models with ideas of mixture models.


Wiadomości Chemiczne, 1998, 52, 773.
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STRUCTURE OF LIQUID WATER. PART II. STRUCTURE OF WATER IN THE PRESENCE OF IONS.

Edward Dutkiewicz, Anna Jakubowska

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


The aim of this work was to present and compare various methods of the determination of the influence of ions on the water structure. The reasons of the discrepancies between the results obtained by different workers and methods are explained.

We have also presented the model of the hydrated ion proposed by Marcus [5]. Marcus [4] used this model to describe the hydration process and its conceptual stages.

In the model of "fluctuating icebergs" proposed by Frank and Evans [11], solutes were considered to order water molecules around themselves. Ordering of water, "iceberg formation" was believed to occur by the development of interconnected networks of hydrogen bounds. Solutes which imposed order, (promoted iceberg formation) were considered to be structure makers. Similarly, solutes which decreased order were said to be structure breakers.

The influence of ions on the water structure can be determined by means of: 1) comparison of the interaction energies among water molecules around the ion with those in pure water [13]; 2) the viscosity B-coefficients of the Dole-Jones equation, the average number of hydrogen bonds in which a water molecule participates ((GHB), a residual entropy (Sstr) and heat capacity of hydration (Cpstr) due to the change in the structure of the water [14]; 3) analyzing the laser-Raman spectra of water in the region of OH stretching [15]. We have compared the results of investigations of structure-making and stucture-breaking properties of the ions (Tab. 1). The observed discrepancies between the results obtained by different workers and methods can be caused:

  1. a different interpretation of the influence of the hydrated ion on the water structure [13, 25, 35, 36],
  2. experimental results depend on the phase of water: bulk or interfacial region, in which the measurements were performed (different properties and structure of both water phases [24, 31, 37 - 43, 44]),
  3. different definitions of the hydration sphere implying a big confusion in the concept of the ion hydration structure [24],
  4. different sensitivity and accuracy of the measurement methods used [24],
  5. different models, assumptions and simplifications,
  6. the different orientation of water dipoles around cations and anions has not been taken into account in models and calculations [5, 47, 50].

Wiadomości Chemiczne, 1998, 52, 787.
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KINETICS OF FAST BIMOLECULAR REACTIONS STUDIED BY FLUORESCENCE QUENCHING. IV. THIOKETONES AS MODEL COMPOUNDS

Marek Sikorski1, Andrzej Maciejewski2 , Marian Szymański3

1Zakład Fotochemii, Wydział Chemii, Uniwersytet im. A. Mickiewicza, ul. Grunwaldzka 6, 60-780 Poznań 2Środowiskowe Laboratorium Unikalnej Aparatury Chemicznej, Uniwersytet im. A. Mickiewicza, ul. Grunwaldzka 6, 60-780 Poznań 3 Zakład Elektroniki Kwantowej, Instytut Fizyki, Uniwersytet im. A. Mickiewicza, ul. Umultowska 85, 61-614 Poznań


We present aromatic thioketones as an excellent set of compounds for investigations of kinetics of fast bimolecular reactions studied by fluorescence quenching. It would be interesting to study seven compounds with fluorescence lifetimes ranging from 64 ps for thioxanthione to 880 ps for 2,2,3,3-tetramethylindanthione in perfluoro-1,3-dimethylcyclohexane (see Table 2). Moreover, the kinetics of fluorescence decay of all the studied thioketones in perfluoroalkanes without a quencher is very well established with xanthione as one of the most thoroughly studied compounds (see Table 3). Previous theoretical work has suggested that investigations of the kinetics of quenching involving compounds with very short fluorescence lifetimes would be a promising avenue of approach to obtaining more definitive experimental information for modeling studies. The aromatic thioketones are such donors. For xanthione, with a lifetime of 178 ps, and 1,3,4,5,6,8-xanthione-d6, with a lifetime of 600 ps, the kinetics of quenching can be described satisfactorily by the SCK theory [42-45]. The parameters such as the sum of donor and quencher radii and the sum of their diffusion coefficients, obtained from this theory, are in rather good agreement with the corresponding values determined by other methods. Unfortunately, a rather large uncertainty in the determination of the proper rate constant k, prevents obtaining an unambiguous answer to the question of whether the large values of k are characteristic of the systems studied or instead are a consequence of the model employed [46,47]. Also the mechanism of quenching of the S2 states of the thioketones by hydrocarbons is not yet clear.


Wiadomości Chemiczne, 1998, 52, 803.
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SYNTHESIS OF SIX-MEMBER NITROGEN HETEROCYCLES IN HETERODIENE REACTIONS

Krystyna Bogdanowicz-Szwed, Małgorzata Krasodomska

Wydział Chemii Uniwersytetu Jagiellońskiego, ul. Ingardena 3, 30060 Kraków


In this article we describe new developments in the synthesis of nitrogen heterocycles by hetero-Diels-Alder reaction covering the literature since 1990. A main point of discussion is stereoselectivity of the reactions and the preparation of enantiopure compounds either by using dienes and dienophiles carrying a chiral auxiliary or by using Lewis acids.

Six-member nitrogen-heterocyclic compounds can be obtained by cycloaddition of aza-1,3-butadienes with carbon dienophiles or by the cycloaddition of electron rich dienes with imines, iminium ions and nitriles acting as dienophiles. 1-Aza-1,3-butadienes may react as electron rich as well as electron deficient dienes in normal cycloaddition or in the cycloaddition with inverse electron demand. E.g. N,N-dimethyl hydrazone prepared from a, b-unsaturated aldehydes 1 react smoothly in normal cycloaddition with electron deficient dienophile [4], (Scheme 1). However N-acyl- and N-sulfony- imines of a, b-unsaturated aldehydes e.g. 10 react as electron deficient dienes in reaction with an inverse electron demand [8], (Scheme 4). Similarly to 1-aza-, 2-aza-1,3-butadienes may react as electron rich or as electron deficient component upon appropriate substitution.

A versatile approach to functionalized pyrimidines involves the reaction of 1,3-diaza-1,3-butadienes 60 with ketenes [23] (Scheme18). Intramolecular cycloadditions of 1,3-diazadienes 71 efficiently yield complex polycyclic molecules [25] (Scheme 20). Theoretical and synthetical studies carried out by van der Plas et al. [29]. deal with intramolecular cycloaddition of 5(w-alkynyl)pyrimidines 77. The substrate initially formed a bridged adducts (Scheme 22), that upon heating release the fused pyridine derivatives and appropriate cyanides by retro Diels-Alder reaction.

The second approach to construction of six-membered nitrogen-heterocycles by Diels-Alder reaction consists in cycloaddition of electron rich dienes with imines or nitriles, that act as dienophiles. Electron deficient imines e.g. acyl- or sulfonyl- imines add to many 1,3-dienes in good yields affording tetrahydropyridines [36,41], (Schemes 27 and 32). The cycloadditions of nonactivated imines have been investigated with regard to the effects of electronically neutral substituents and the influence of Lewis acids. The recent work in this area deals with asymmetric induction in azadiene reaction. E.g. the utility of chiral imines derived from enantiopure amino acids 93 in cycloaddition with electron rich diene in presence of Lewis acid lead to pyridone 95 in very good diastereoselectivity (95% de) [36] (Scheme 27). Chiral Lewis acids were also used in order to carry out enantioselective Diels-Alder reactions starting from achiral substrates and chiral catalyst. E.g. the reaction of imine derived from 3-pyridineformaldehyde 106 and Danishefsky's diene 89 afforded the desired cycloadduct 107 in high optical purity [40], (Scheme 31). Cyanides have been found to be less reactive than imines since the reactions require of extremely high temperatures. However sulfonyl nitriles 112 react with a variety of dienes under much milder conditions affording pyridine derivatives 114 [42].


Wiadomości Chemiczne, 1998, 52, 821.
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THE STORY OF TAXOL : ECSTASY AND TORMENT

Karol Kacprzak

Zakład Chemii Produkt(w Naturalnych Wydział Chemii UAM ul. Grunwaldzka 6, 60-780 Poznań


Taxol (1), a highly functionalised complex diterpenoid orginally derived from the bark of Pacific yew, has received in recent decade wide attention of scientists in all fields of life sciences and chemistry, after the discovery of its strong and unique anticancer properties. Fast and spectacular career of this molecule (Table 1) is a subject of the present review. The large scale of research on Taxol is the consequence of public and commercial response to successfull treatment of various cancer diseases and impossibility of solving basic technological and intellectual problems such as: production, drug formulation, structure-activity relationship elucidation. The discussion in divided in separate sections:

1. Activity and pharmacological phenomena of Taxol.

2. Production of Taxol by biotechnological and chemical methods, including synthesis of Taxol side chain.

3. Structure-Activity relationship (SAR) of Taxoids.

After Horwitz reported in 1979 a strongly antimitotic activity of Taxol [3], interest in developing the pharmacology and biochemistry of this class of natural products increased.

Taxol molecule promotes anticancer activity by enhancing polymerization of tubulin and stabilization of microtubules [6]. This process has the effect of inhibiting the normal dynamic reorganization of the cytoskeleton (which consist of microtubules) that is necessary for interphase and cell division in mitosis [4].

Taxol and Taxotere are successfully used for the treatment of a variety of cancers, in particular ovarian and breast cancer [10], [11].

The biggest problem hindering wider application of this drug is its limited availability from natural sources. One kg of Taxus brevifolia bark yields only 100-170 mg of Taxol, after long and complicated extraction procedure. Since the yew is slow growing species this methode of obtaining the drug is controvertible and unprofitable (see scheme 2). An alternative source of Taxol is semisynthesis (see scheme 3) [48], where natural precursor of Taxol 10-deacetylbaccatin (10-DAB) can be extracted from regenerable twings of popular yew Taxus baccata [32] and after coupling with synthetically prepared side chain (see table 2 and refrences cited therein) can be converted to Taxol or Taxotere.

Taxol has also been prepared by a number of total syntheses [66-70] but none of these is expected to enter the phase of commercial production. Biotechnological approaches to production by tissue culture [27-31] or fungi cultivation [24] have been reported.

Studies in the area of Taxoids structure-activity relationships have first demonstrated two basic principles. The so-called 'southern' substituents, such as C-2 benzoate and the side chain, are crucial for the activity. 'Northern' substituents at C-7, C-9 and C-10 can be changed without drastic effect on the activity. The role of the substituents at C-1, the oxetane ring and diterpenoid core modifications are less well understood.

There are many reports of significant activity of highly transformed taxoids, including those with: modified ABC core (scheme 15 [92-93]), open C-ring structure (picture 2 [96]) and aromatic C-ring (picture 2 [94]).

These results indicate the possibility of obtaining a synthetic, structurally simplified variant of Taxol.


Wiadomości Chemiczne, 1998, 52, 843.
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LOW MOLECULAR INHIBITORS OF PLASMIN

Krystyna Midura-Nowaczek

Uniwersytet w Białymstoku, Instytut Chemii, Al. J. Piłsudskiego 11/4, 15-443 Białystok


Plasmin, serine protease with trypsin specifity, plays a key role in the process of fibrinolysis. Analogs of lysine like (-aminocaproic acid and t-4-aminomethylcyclohexanecarboxylic acid (Fig. 2) are employed clinically as plasmin inhibitors [6] and exhibit an inhibitory effect by blocking lysine binding sites of the enzyme (Figs. 3, 4) [10-14]. Their inhibitory activity on plasmin with the respect to fibrynogen and other proteins is much weaker than towards fibrin. Because of this reason, investigations on the synthesis of an active centre directed inhibitors of plasmin were also undertaken. A great number of compounds was obtained including derivatives of w-aminoacids (Figs 5, 6) [15, 16] or lysine (Fig. 10) [35-38, 44]. Next important group were short peptides with C-terminal lysine or arginine derivatives such as aldehydes (Fig. 8) [17-25], chloromethylketones [26-30], fluoromethylketone [31], methylketones [33], amides [37, 40, 41] or esters [41]. This paper presents literature data on structure-activity relationship for low molecular inhibitors of plasmin with a structure of aminoacids or peptides derivatives .


Wiadomości Chemiczne, 1998, 52, 871.
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Notatki chaotyczne. XVIII. FILOZOFIA A CHEMIA.

Ignacy Z. Siemion

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



Wiadomości Chemiczne, 1998, 52, 889.
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