Wiadomości Chemiczne

Wiadomości Chemiczne, 2001, Vol. 55

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  1. A celebration of 45 years of scientific work and the 70th birthday of professor Bogdan Burczyk
    Kazimiera A. Wilk

  2. Selenium compounds as the reagents and catalysts for oxidation of organic compounds
    Jacek Młochowski, Monika Brząszcz, Mirosław Giurg, Halina Wójtowicz

  3. Serotonin receptor ligands in migraine therapy
    Beata Duszyńska, Stanisław Misztal

  4. Trends toward discovering new drugs improving learning, memory and cognitive function
    Barbara Malawska

  5. Natural and synthetic insect antifeedants. Part I
    Edyta Paruch

  6. Natural and synthetic insect antifeedants. Part II
    Edyta Paruch

  7. Colloidal silica - structure and properties
    Andrzej Krysztafkiewicz, Teofil Jesionowski

  8. Centenary of Planck's equation and constant
    Adam Kiejna

  9. Mosaic gold in Europe and China
    Anthony R. Butler, Christopher Glidewell, Joseph Needham, Sharee Pritchard

  10. Notatki chaotyczne. XXXII. Pół wieku temu
    Ignacy Z. Siemion

  11. Carba-sugars (pseudosugars) and cyclofellitols
    Ryszard Frankowski, Zygfryd Smiatacz

  12. Paxillus involutus, a popular mushroom of controversial physiological properties
    Wiesław Zygmunt Antkowiak

  13. Mixed-ligand complexes in the aspect of their role in chemistry and in living systems
    Danuta Kroczewska, Barbara Kurzak

  14. An intercalation electrode in lithium cell with nonaqueous electrolyte solution.
    I. Manganese dioxide and lithium-manganese oxides

    Maria Bełtowska-Brzezinska, Tomasz Kozik, Halina Jaworska

  15. Platinum and its compounds in human environment - are they dangerous?
    Barbara Leśniewska, Krystyna Pyrzyńska, Beata Godlewska-Żyłkiewicz

  16. Influence of Aluminium Chemical Activity on Detonation Parameters of Composite Explosives Containing
    Andrzej Maranda

  17. Searching of g-amino- and g-hydroxybutyric acid analogs with expected anticonvulsant activity
    Barbara Malawska

  18. Notatki chaotyczne. XXXIII. Wiedza mineralogiczno-chemiczna w Polsce w czasach Bolesławów
    Ignacy Z. Siemion

  19. Glenn Theodore Seaborg - a chemist and physicist
    Albert Ghiorso, Darleane C. Hoffman, Adam Sobiczewski

  20. Photo- and electroconducting conjugated polyenes
    Kazimiera A. Wilk, Beata W. Domagalska

  21. Modelling of enzymatic depolymerisation reactions using Monte Carlo method
    Piotr M. Wojciechowski

  22. The protecting groups of the amino function in D-glucosamine
    Dorota Bednarczyk, Henryk Myszka

  23. Sweet compounds containing sulphur
    Krystyna Jarzembek

  24. The methods of preparation of phenyl-trifluoromethyl sulfides
    Arkadiusz Mizerski, Zbigniew Ochal

  25. Effect of polymers on properties of dispersions of nanoparticles
    Waldemar Nowicki, Grażyna Nowicka

  26. Notatki chaotyczne. XXXIV. O pochodzeniu homochiralności ziemskiej i o dichroizmie magnetochiralnym
    Ignacy Z. Siemion

  27. Hydrogen bonding - Selected problems
    Lucjan Sobczyk

  28. Density functional calculations of interaction of molecular hydrogen with transition metals. Perspectives of quantum models of heterogeneous catalysis
    Witold M. Bartczak, Stanisław Romanowski, Marcin Łandwijt

  29. Alkoxyallenes. Methods of preparation and application to organic synthesis
    Robert Łysek, Marek Chmielewski

  30. Thermoelectric rattlers:compounds with structure of filled skutterudite
    Wojciech Suski

  31. Combustion of mixtures of metals with fluorocarbon polymers
    Stanisław Cudziło

  32. Arylpiperazine ligands of serotonin (5-HT)1A / 5-HT2A receptors
    Ewa Chojnacka-Wójcik

  33. Notatki chaotyczne. XXXV. Wiktor von Richter - pierwszy na ziemiach polskich rzecznikidei Mendelejewa
    Ignacy Z. Siemion

  34. New natural products with cytostatic activity
    Agnieszka Gryszkiewicz, Izabella Jastrzębska, Jacek W. Morzycki

  35. Cyclitols
    Ryszard Frankowski, Wojciech Maszewski i Zygfryd Smiatacz

  36. Alternative mediators of mitsunobu reaction
    Bogdan Falkiewicz, Kazimierz Wiśniewski, Aleksandra S. Kołodziejczyk

  37. Organosilicon derivates of b-diketones - synthesis, properties and main application
    Włodzimierz Urbaniak

  38. Enzymatic degradation of halogenated organic compounds
    Andrzej Lewandowicz

  39. Studies on solution uv-vis spectroscopy of transition metal complexes with schiff bases
    Krzysztof Kurzak, Iwona Kuźniarska-Biernacka

  40. Modes of on-capillary sample concentration in high performance capillary electrophoresis
    Angelika Mrass, Edward Bald

  41. Notatki chaotyczne. XXXVI. Zmienne fata pytań kardynalnych
    Ignacy Z. Siemion

  42. Radiation chemistry and origins of life on earth
    Zbigniew Paweł Zagórski

  43. Bioflavonoids as natural antioxidants
    Jadwiga Wilska-Jeszka, Anna Podsędek

  44. The influence of reduction temperature on the sorption and catalytical properties of supported metalic systems
    Stanisław Karski, Iwona Ludomirska, Izabela Witońska

  45. Spectroscopic studies of heteropolyanions and their complexes with lanthanide(III) ions
    Stefan Lis, Sławomir But

  46. Lipophilicity, methods of determination and its role in biological effect of chemical substances
    Krzysztof Jóźwiak, Halina Szumiło, Edward Soczewiński

  47. Simultaneous determination of fat-soluble vitamins by means of HPLC
    Sławomir Wieliński, Andrzej Olszanowski

  48. Transformations of graphite and boron nitride in shock waves
    Radosław Trębiński, Andrzej Maranda

  49. Notatki chaotyczne. XXXVII. O odkryciach przedwczesnych
    Ignacy Z. Siemion

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A celebration of 45 years of scientific work and the 70th birthday of professor Bogdan Burczyk

Kazimiera A. Wilk

Instytut Technologii Organicznej i Tworzyw Sztucznych, Wydział Chemiczny, Politechnika Wrocławska, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław


In 2000 professor Bogdan Burczyk celebrated the 45th anniversary of scientific activity and the 70th birthday. He is one of the most meritorious for both the Institute of Organic and Polymer Technology of the Department of Chemistry of Wrocław University of Technology, and the surfactant chemistry scientific society.

Professor Bogdan Burczyk received his M.Sc. in chemistry in 1955 (employment - 1 XII 1954), Ph.D. in technical sciences - in 1962, habilitation (D.Sc.) in chemical sciences - in 1970 at the Department of Chemistry of Wrocław University of Technology. He became a professor of chemical sciences in 1976. His postdoctoral studies have been carried out in 1964-1965 at the Institute of Organic Chemistry and Biochemistry of the Czechoslovak Academy of Sciences in Prague, and in 1969 at the Central Institute of Organic Chemistry of the Academy of Sciences of the German Democratic Republic in Berlin.

Professor Burczyk has been particularly active in both research and teaching concerning surfactant sciences: synthesis of chemodegradable, acetal-type surface active substances containing nonionic and polar groups, as well as nonionic aldonamide surfactants; relationship: chemical and geometrical structure - surface activity of amphiphilic compounds. The second area of his research are selected problems of industrial organic chemistry: synthesis and properties of acetals and ethers; chemical industry in relation to the environment including principles of the so-called "green chemistry'. Under his scientific supervision eigth persons received their Ph.D. and five later reached the highest levels in their scientific careers. His research has so far resulted in about 110 original scientific papers (published, among others, in such respectable journals as: J. Colloid Interface Sci., J. Phys. Chem., Langmuir, Colloids Surfaces, J. Am. Oil Chem. Soc.), 45 patents and 33 review articles. He is a member of several Polish and foreign scientific societes, scientific councils, boards and committees.


Wiadomości Chemiczne, 2001, 55, 1.
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SELENIUM COMPOUNDS AS THE REAGENTS AND CATALYSTS FOR OXIDATION OF ORGANIC COMPOUNDS

Jacek Młochowski, Monika Brząszcz, Mirosław Giurg, Halina Wójtowicz

Instytut Chemii Organicznej Biochemii i Biotechnologii, Politechnika Wrocławska, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław


Oxidation reactions are fundamental processes widely applied in organic synthesis. Among many reagents used in these reactions, elemental selenium and particularly some of its compounds have been reported as effective and selective oxidants and catalysts for the oxidation of various organic substrates [5, 6, 10, 37]. One of them is selenium(IV) oxide, easily available regent for hydroxylation of activated a-positions particularly at allylic and propargylic sites. It also can introduce carbonyl functionality at activated positions. Used in combination with hydrogen peroxide or t-butylhydroperoxide it acts as oxygen-transfer agent. Both of these hydroperoxides can be used in the presence of seleniumu(IV) oxide for epoxidation, 1,2-dihydroxylation and a-carbonylation of alkenes, for oxidation of aldehydes into carboxylic acids, sulfides to sulfoxides or sulfones, secondary amines to nitrones and for other reactions [5-10, 22, 23, 36, 37, 47, 48, 61, 71, 89, 91,92].

Benzeneseleninic acid, other areneseleninic acids and their anhydrides are known as stoichiometric oxidants or activators of other oxygen donors. They have been successfully applied for oxidation of many organic compouns, among them alkenes, alcohols, phenols, amines, hydrazones, sulfides, 1,3-dithiolanes and azines [5, 10, 105, 107, 120, 129, 133, 144].

Organic diselenides, the precursors of seleninic acids, have been used as oxygen-transfer catalysts for oxidation of various functional groups with hydrogen peroxide, t-butylhydroperoxide and other oxygen donors [152-154, 163-165, 168-174] while dimethyl and diphenyl selenoxides are efficient stoichiometric oxidants (e.g. for conversion of halomethyl or hydroxymethyl group into formyl group) [177-189].

Most recently, selenenamides, particularly 2-phenyl-1,2-benzisoselenazol-3(2H)-one (ebselen) and its analogous were found as efficient catalysts for hydrogen peroxide and tbutylhydroperoxide oxofunctionalization of olefins, oxidation of azomethine compounds and sulfides [163, 165, 202].


Wiadomości Chemiczne, 2001, 55, 9.
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SEROTONIN RECEPTOR LIGANDS IN MIGRAINE THERAPY

Beata Duszyńska, Stanisław Misztal

Zakład Chemii Leków Instytutu Farmakologii Polskiej Akademii Nauk, ul. Smętna 12, 31-343 Kraków


Migraine is a common, chronic disorder affecting the lives of millions of people worldwide. It is characterized by a throbbing headache, which is usualy unilateral, and is often associated with nausea, vomiting, photophobia and phonophobia. The precise mechanisms underlying the cause of migraine are still unclear and several theories regarding its etiology have been proposed. The vasodilatory theory of migraine suggested that extracranial arterial dilatation during an attack was related to migraine pain; the neurological theory propossed that migraine resulted from abnormal firing in brain neurons. The neorogenic dural inflammation theory supposed thet the dural membrane surrounding the brain become inflammed and hypersensitive due to release of neuropeptides from primary sensory nerve terminals. Substantia P, calcitonin gene-related peptide (CGRP) and nitric oxide are all thought to play a role in the dural inflammation cascade.

Several clinical and experimental observations confirm that serotonin (5-hydroxytryptamine, 5-HT) has an important role in producing or maintaining migraine attack. The serotonin connection with migraine is additionally supported by the efficacy of serotonin receptor ligands. Sumatriptan - designed to interact with the specific type of serotonin receptors - was the first drug marketed worldwide for acute treatment of migraine. It activates 5-HT1B/1Dserotonin receptors on nerves and blood vessels and in so doing turns off inflammation and shrinks swollen blood vessels, believed to contribute to migraine pain.

The introduction and the success of sumatriptan initiated an intense search for improved triptamide derivatives. New medications are being released in rapid sequence. Today four second-generation triptans are on the market: zolmitriptan, naratriptan, rizatriptan and almotriptan and two others (eletriptan and frovatriptan) are about to be marketed.

All of the triptans share a common mode of action, but the new ones are more lipophilic and have higher oral bioavailability than sumatriptan. Adverse events for triptans include: tightening, flushing and paraesthesias of unknown case. All of them cause narrowing of arteries, including coronary arteries, and although serious adverse vascular events are very rare, triptan use is contraindicated in patients with vascular disease.

Finally, a problem with the triptans is a recurrence of headache a few hours after initial successful treatment. Because clinical-trial data suggest that the differences among the various triptans are subtle rather than dramatic, it is not yet clearly established whether these new agents represent a major improvement over sumatriptan in therapeutic effectiveness.

Despite an indisputable progress in migraine therapy triptans have not yet provided an optimal answer and future work in this field is still warranted. Recently, a novel arylpiperazine derivative of serotonin with potent, selective and unique high intrisic activity at 5-HT1B/1D receptors (F 11356) is developed to be superior over the representatives of triptans family.

Apart from the 5-HT1B/1D agonists several other classes of ligands have been suggested as potentially beneficial in acute treatment of migraine, namely 5-HT1F agonists and 5-HT2H antagonist.

These new directions as well as a review of a currently available antimigraine drugs from the family of 5-HT receptor ligands are summarized in this article.


Wiadomości Chemiczne, 2001, 55, 45.
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TRENDS TOWARD DISCOVERING NEW DRUGS IMPROVING LEARNING, MEMORY AND COGNITIVE FUNCTION

Barbara Malawska

Katedra Chemii Farmaceutycznej Collegium Medicum Uniwersytetu Jagiellońskiego 30-688 Kraków, ul. Medyczna 9


This review attempts to briefly summarise the recent developments in the study of new compounds improving learning, memory and cognitive function. A large number of compounds belonging to many different chemical classes have been proposed as cognition enhancers. Three groups of compounds - nootropics, cholinergic drugs and neuromodulators are presented [3].

Most compounds described as nootrpics are 2-pyrrolidone derivatives, the prototype of which is piracetam (Nootropil) [4-6]. Nootropics facilitate learning and memory in animal models [5-25]. Clinical trials have yielded unconvincing results, however some new drugs such as nefiracetam [9, 10] and fasoracetam [20-22] appear promising.

Central cholinergic systems have been repeatedly shown to play an important role in learning and memory. The deficits in cognitive and memory performance observed in aged humans and in Alzheimer's disease (AD) patients are due at least in part to deficient cholinergic functioning[26-29]. Augmentation of cholinergic neurotransmission might be accomplished in several different ways [33-37]. Cholinergic agonists directly acting on muscarinic receptors may improve the defective cholinergic function seen in AD [36]. Selective second-generation muscarinic agonists appear promising and are in various stages of preclinical and clinical evaluation, including milameline [41], itameline [42, 43], xanomeline [44, 45], sabcomeline [49, 50] and talsaclidine [51]. These compounds are chemically related to the naturally occurring muscarinic agonist, arecoline [33].

The prototypical neuronal acetylcholine receptors agonist nicotine has been shown to ameliorate some of the symptoms of AD, and, in a number of animal models, to have neuroprotective effects [52-54]. Some nicotinic agonists were reported to be active in animal models of memory and learning, such as compounds ABT-418, ABT-089 and SIB-1553A [55-57].

Acetylcholinesterase (AChE) inhibition is presently the most successful method to ameliorate cholinergic deficit and lead to symptomatic improvement. About 30 AChE inhibitors are currently being studied word-wide in preclinical or clinical studies [3, 33, 35, 37]. AChE inhibitors are broadly classified in three categories. These include: the carbamates such as physostigmine, eptastigmine [59], phenserine [58] and rivastigmine; the aminoacridines such as tacrine, velnacrine, suronacrine [35], and their derivatives ipidacrine [68] and compound SM-10888 ; the benzylpiperidines such as donepezil, T-82 [72], TAK-147 and CP-118954 [73-75]. Tacrine was the the first drug approved in 1993 in USA for treatment of senile dementia of the Alzheimer type [66, 67]. Rivastigmine [63-65], and donepezil [69-71] were approved in 1997. Cymserine and bis-norcimserine are derivatives of the alkaloid physostigmine. These compounds represent the first available potent, reversible, and selective inhibitors of butyrylcholinesterase [60-62]. The organophosphate metrifonate has been extensively studied in animals and recently evaluated in AD. Metrifonat is an inactive prodrug, but is non-enzymatically transformed into the active compound dichlorvos that irreversibly inhibits AChE [76, 77].

There are many reports on the interaction between the cholinergic system and other putative neurotransmitter on the central nervous system. Therefore, such transmitter interactions play an important role in the regulation of learning and memory. Modulators, the third group of compounds represents different structures. A wide variety of substances have been shown to facilitate memory, including: opioid agonist (SA 4503) [78, 79], a benzodiazepine inverse agonist (S-8510) [85, 86], modulator of noradrenergic transmission (CR 2249) [87]; derivatives of piperazine (FK-960 [80, 81], ensaculine [83]) and peptides (NC-1900) [88].


Wiadomości Chemiczne, 2000, 55, 67.
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NATURAL AND SYNTHETIC INSECT ANTIFEEDANTS, PART I

Edyta Paruch

Katedra Chemii, Akademia Rolnicza we Wrocławiu ul. Norwida 25, 50-375 Wrocław e-mail: paruch@ozi.ar.wroc.pl


Insect antifeedants are chemicals which inhibit feeding, but do not kill the insect directly, the insect often remaining near the antifeedant source and possibly dying through starvation. Many antifeedants have been found in plants, being a part of their protective system against its predators.

Antifeedants, unlike pesticides, are often selectively toxic towards some insect species, whereas they are not harmful to the other ones and to mammals. As crop protection currently relies upon the use of broad spectrum of pesticides, friendlier to environment antifeedants are focus of recent research. Their current use is limited, as it is difficult to obtain them in useful quantities. Moreover, most of them are highly complexed molecules, which are not readily synthesised. The aim of researchers is to obtain a synthetic antifeedant of a simple structure, which retain the potency of natural products and fulfil synthetic requirements to be of practical use.

The mono- and sesquiterpenoid natural and synthetic antifeedants are presented here. There are few natural monoterpenoid compounds of deterrent activity (fig. 3) [14-18], whereas there are many numerous groups of sesquiterpene ones. The most known among sesquiterpenes are drimanes (fig. 4), isolated from bark of Drimys species, containing bicyclofarnesane skeleton - active antifeedants against aphids [19,20]. The second large group are compounds isolated from mushrooms of Lactarius species, divided into marasmanes (fig. 9) and lactaranes (fig. 10, 11), active towards stored products pests [38-40].

Many synthetic derivatives of natural antifeedants have been investigated so as to find correlation between structure and activity [27,39-42]. Biological data showed that there is no single functional group responsible for deterrent activity. Even a small structure modification in different parts of a molecule may reduce the activity drastically. However, it is significant, that en-dialdehyde function, as well as g- or d-lactone ring are often present in active feeding deterrents. Sesquiterpene lactones, isolated from wide range of plants, are a very large group of insect antifeedants (fig. 11, 13-19) [46-59].

Mono- and sesquiterpene lactones are the most promising compounds in search of new, synthetic insect antifeedants. Several synthetic terpenoid lactones of twelve carbon atoms, active deterrents against stored grain pests, are also presented (fig. 20) [60-64].


Wiadomości Chemiczne, 2000, 55, 67.
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NATURAL AND SYNTHETIC INSECT ANTIFEEDANTS, PART II

Edyta Paruch

Katedra Chemii, Akademia Rolnicza we Wrocławiu ul. Norwida 25, 50-375 Wrocław e-mail: paruch@ozi.ar.wroc.pl


Antifeedants, chemicals which prevent insects from feeding, have been at the centre of interest of researchers for the last forty years. Most of them are of natural origin., being a part of plant protective system. Antifeedants of followin groups: diterpenoids (including degraded limonoids), triterpenoids, alkaloids, lignanes, flavonoids, and coumarine derivatives are presented here.

The most numerous group of diterpenoids are cleradanes, isolated mainly from plants of Teucrium genus [17]. Clerodin (fig. 2) [8-12], ajugarin (fig. 1) [1,2] and jodrellin (fig. 3) [18] are the best known members of this group. The second large group are limonoids, belonging to tetranortriterpenes, found mainly in plants of Meliaceae and Rutaceae family. The main compound of this group is azadirachtin (fig. 10), isolated from Azadirachta indica (Meliaceae) [36, 58]. Not being harmful to mammals, it displays strong feedingdeterrent activity towards a great number of insect species. Huge amount of limonoids has beeb found in plants (figs 11-13, 15) [60-69]. Advanced studies on the synthesis and correlation between chemical structures and biological activity for clerodanes [3-7, 11, 12, 19-25] and limonoids [48-58' 70-74] have been carried out. Synthetic fragments of natural antifeedants, which exhibit activity comparable to the natural compounds, are also presented (figs 1, 3, 10) [3-5, 19, 48].

Degraded limonoids are the natural and synthetic diterpenoid compounds, the structures of which are fragments of natural limonoids (figs 16-19). Great interes has been taken in this group for the last 10 years [76-90].

Some alkaloids are also presented here (figs 20-22), as they are one of the first known insect antifeedants [92-96]. They are active towards different insect species [97-103], including stored grain pests [91]. Feeding deterrents of lignanes [105, 106] and flavonoids [107] are shown on fig. 24. The last presented group are coumarine derivatives (fig. 25), active against Spodoptera litura [108, 109]. In this case studies on structure-activity correlation were carried out as well (fig. 26 - the most active synthetic coumarine antifeedans).

The perception of antifeedants at the sensory level may involve different mechanisms [44]. Feeding deterrents may stimulate specialized receptors tuned to other compounds and thus alter the sensory code. There is also a hypothesis, based on electrophysiological data, that the impulses from different receptors are not received independently, but in a comlexed form. Modification of this neural code changes insect's behaviour.

On the basis of biological data it has been postulated that polyphagous insets are less sensitive to antifeedants than more specialised species [116-118].


Wiadomości Chemiczne, 2001, 55, 119.
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COLLOIDAL SILICA - STRUCTURE AND PROPERTIES

Andrzej Krysztafkiewicz, Teofil Jesionowski

INSTYTUT TECHNOLOGII I INŻYNIERII CHEMICZNEJ POLITECHNIKA POZNAŃSKA pl. M. Skłodowskiej-Curie 2, 60-965 Poznań e-mail: Teofil.Jesionowski@put.poznan.pl


Natural amorphic silicas were charactrized, present in the form of minerals. Subsequently, synthetic products based on the amorphic silica were described, including, so called, colloidal silica (silica gels, xerogels, aerogels, pyrogenic silicas, precipitated silicas and coacervate silicas).

Particle structure of the amorphic colloidal silica was presented and compared to that of silica crystals (e.g. of quarz crystals). Particular attention was given to the outer structure of silica colloidal particles and two types of silanol groups, present on the surface of the particles. Methods of the surface stabilization in the alcaline medium were indicated.

Subsequently, effects of temperature on the amounts of individual types of silanol and siloxane groups on the surface of colloidal silicas were discussed.

In the next chapter of the presentation physical and selected chemical properties of the silicas were presented. Attention was payed also to the most significant issue of stabilization of silica colloidal systems.


Wiadomości Chemiczne, 2000, 55, 151.
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CENTENARY OF PLANCK's EQUATION AND CONSTANT

Adam Kiejna

Instytut Fizyki Doświadczalnej, Uniwersytet Wrocławski, pl. M. Borna 9, 50-204 Wrocław


The development of ideas and events that led to the announcement of the theory of black body radiation by Planck, on 14 December 1900, is described. This date marks 100 years of the quantum theory.


Wiadomości Chemiczne, 2001, 55, 173.
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MOSAIC GOLD IN EUROPE AND CHINA

Anthony R. Butler, Christopher Glidewell, Joseph Needham, Sharee Pritchard


Translated from: Chemistry in Britain, 1983. Feb., 132
Translation: Jan Morawiec


The paper discisses and compares old recipes for mosaic gold {tin(IV) disulphide} of European and Chnese alchemists. The authors have also checked the reactions using some modern methods, like thermal analysis and thermodynamics, concluding that the Chinese recipes are fully credible.


Wiadomości Chemiczne, 2001, 55, 189.
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NOTATKI CHAOTYCZNE. XXXII. PÓŁ WIEKU TEMU

Ignacy Z. Siemion

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



Wiadomości Chemiczne, 2001, 55, 197.
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CARBA-SUGARS (PSEUDOSUGARS) AND CYCLOFELLITOLS

Ryszard Frankowski, Zygfryd Smiatacz

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


Investigations into carba-sugars have been initiated by McCasland [1, 17, 21] in 1966. Studies in this area have subsequently been continued by Suami [9, 18-22, 26, 40] and Paulsen [25], whereas cyclophellitols were investigated by a Japanese team headed by Umezawa [28]. By now, cyclophellitols are also studied by Jung [34], Roberts [36] and Ziegler [37,38].

The first chapter of this review paper deals with the definition of carba-sugars and reports on first syntheses of the compounds [1].

The second chapter is devoted to the detection of carba-sugars in Nature, their structure and biological activity. The structure and antibiotic/inhibitory activities have been presented of such carba-sugars as validamycins A and E, validamine, acarbose, trestatine B, amylostatine, valiolamine, validatol and other representatives of this group of compounds [2-20] including prostaglandins [11, 12].

Induction of a sweet taste by carba-sugars based on the triangle of sweetness has been discussed [13-16].

The third chapter deals with the common methods of synthesis of carba-sugars. These are as follows:

The fourth chapter is confined to cyclophellitols, the derivatives of pseudosugars containing oxirane ring at positions C-1 and C-2 (Scheme 21). Their detection, properties and syntheses have been desribed (Schemes 22 and 23). The thiirane [33] and aziridine [29] analogues of cyclophellitols have been mentioned, as well (Scheme 29).


Wiadomości Chemiczne, 2000, 55, 221 .
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PAXILLUS INVOLUTUS, A POPULAR MUSHROOM OF CONTROVERSIAL PHYSIOLOGICAL PROPERTIES

Wiesław Zygmunt Antkowiak

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


Paxillus involutus, bearing the Polish name olszówka or krowiak podwinięty, is a very common mushroom of a large size, the toxic properties of which revealed much controversy. Besides ordinary people's opinion of the eatability of this mushroom, a number of literature reports showed the fatal consequences of P.involutus consumption. Most often, the symptoms of intoxication shown by different authors concerned changes in the blood, especially those resulting in hemolytic anemia. Although the physiological mechanism of the fatal poisonings was proposed, the toxicity problem is still unsolved because, on the one hand, in many cases the intoxication symptoms have not been observed after mushroom consumption, and, on the other hand, the chemical search for the metabolite responsible for the toxic properties has been unsuccessful up to now.

The hitherto obtained results of the research carried out on the chemical composition of P.involutus mainly since the late Sixties of the twentieth century showed the presence of such metabolites as fatty acids, carbohydrates, peptides and other nitrogen containing compounds (including a trace of muscarine) known from their occurrence in other fungi species, as well as of pigments involutine and involutone and presumably two other compounds structurally related to them.

All the isolated metabolites and those metabolites whose presence was only suggested on the basis of chromatographic observations are not supposed to be responsible for the toxic properties of P.involututs . Therefore, precise further investigations carried out on the mushroom's chemical composition, including the metabolites enzymatically formed as a response to a mechanical injury of the fruit bodies, seem to be essential.


Wiadomości Chemiczne, 2001, 55, 245.
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MIXED-LIGAND COMPLEXES IN THE ASPECT OF THEIR ROLE IN CHEMISTRY AND IN LIVING SYSTEMS

Danuta Kroczewska, Barbara Kurzak

Instytut Chemii Akademia Podlaska, ul. 3-Maja 54, 08-110 Siedlce


During the last two decades thousands of important papers and some excelant review concerning complex equilibria have been published. In fact, most of these papers concern data on complex equilibrium, which does not involve species other than simple complexes with a completely homogenous coordination sphere

Because mixed-ligand complexes are the most general and probable forms of existence of the elements in solution, we would like to present the mixed-ligand complexes in the aspect of their role in chemistry and in living systems.

In the first part of this text we have lain particular emphasis upon literature data which show that it is worthwhile to assemble information on the formation, stability, structure and on the mutual influence of two ligands bound to the same metal ion, in the next part - on biochemical processes (transport, storage, inhibition of anzyme processes) which might be simulated by mixed-ligand complexes as "model systems" and at last - on own studies upon the mixed-ligand complexes of hydroxamic acid (a- or b-alaninehydroxamic acid) and one of polyamines with different metal ions. In order to find the answer for the following question: what kind of stoichiometry, geometry and binding mode there is in complexes which arrive in studied ternary systems? We used different methods: pH-metric method and spectroscopic ones (UV-VIS, EPR and NMR).

The results obtained in our investigations and presented in this text show that the steric effect plays a very important role in the formation of the mixed-ligand complexes. In the case of bulky polyamine bonded in the zink(II) equimolar complex the coordination of a- or b-alaninehydroxamic acid is more favoured than the second polyamine ligand. There is no mixed-ligand complex formation in the case of ternary sestems with nickel(II). The reason for this is in the geometry of parent complexes - octahedral for nickel(II)-amine and square planar for nickel(II)-a-Alaha systems. The tridentate coordination of diethylenetriamine results in five-coordinated mixed-ligand copper(II) complexes in which the aminohydroxamate moiety adopts an equatorial-axial coordination mode.


Wiadomości Chemiczne, 2001, 55, 263.
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AN INTERCALATION ELECTRODE IN LITHIUM CELL WITH NONAQUEOUS ELECTROLYTE SOLUTION.
I. MANGANESE DIOXIDE AND LITHIUM-MANGANESE OXIDES

Maria Bełtowska-Brzezinska, Tomasz Kozik, Halina Jaworska*

Wydział Chemii, Uniwersytet im. A. Mickiewicza, 60-780 Poznań, Grunwaldzka 6
*Katedra Biochemii Żywności, Uniwersytet Warmińsko-Mazurski, Olsztyn, Pl.Cieszyński 1


Lithium batteries of various types have found use in portable electronic devices and are also considered for application in electric or hybrid vehicles because of their high operating voltage and energy density [1-26]. Among a number of materials examined as the positive electrode in lithium batteries with organic electrolyte solution, much attention has been paid to transition metal oxides, in particular to manganese dioxide and its lithiated derivatives. Electrochemical studies have proved that these compounds are able to accommodate or remove Li+ ions in parallel with the electron injection or extraction thus changing the oxidation state of manganese (IV/III) upon the solid state redox reaction [27-37]. The capacity and power density of intercalation electrodes varies with the crystallographic and electronic structure of their solid phase [22, 34, 54-67], electrode thickness and porosity as well as the chemical nature and conductivity of the electrolyte solution [68-74]. The kinetics of the electrochemical intercalation-deintercalation of Li+ ions is mostly limited by the diffusion of these ions into or from the host matrix. Another limitation comes from an electrolyte depletion in pores of the electrode material during the discharge, as the rate of the Li+ ions transport from the bulk electrolyte is lower in comparison with the charge transfer rate at the electrode/electrolyte interface. The diffusion model for nonporous and porous intercalation electrodes [68, 69, 74] quite well describes the surface and bulk distribution of Li+ ions in the solid phase as well as in the pore electrolyte, as a function of the discharge rate and discharge degree (Fig. 1 to Fig. 4). The experimental characteristics of MnO2 and compounds of the Li-Mn-O system, obtained at various electrode thickness, particle size and charge-discharge density has confirmed the theoretical predictions (Fig. 10 and Fig. 11) [49, 73, 85, 108-112, 137, 138, 162, 230, 302, 379].

Manganese dioxide (g-MnO2) electrodes having discharge capacity of 220-270 Ah/kg at E»3 V vs. Li/Li+ (Fig. 6) [62, 79, 94-103, 106, 107] show a limited rechargeability on charge-discharge cycling in secondary lithium cells (Fig. 5) [65, 85, 88, 102-104, 113-119]. As evidenced by XRD-ray patterns this is due to anisotropic expansion and contraction of the crystallographic unit cell at the average manganese valence of about +3.5 [62-64, 79, 88, 103, 105]. A significantly higher cycling efficiency can be achieved with MnO2(CDMO) [121-129] and Li-Mn-O spinel phases (Fig. 7, Fig. 8) [49, 64, 131-192], providing a three-dimensional interstitial space for Li+ ions transport. The cubic close-packed structure of the stoichiometric LiMn2O4 remains almost unchanged upon deintercalation to l-MnO2 and subsequent reintercalation to x » 1 in the potential range E » 4 V (vs. Li/Li+). One can obtain the rechargeable capacity of 125 Ah/kg at moderate current rates [49, 64, 131, 144, 147, 149, 193-195] owing to the relatively fast solid state diffusion of Li+ ions for 0< x <1 [49, 132, 140, 180]. Two further potential plateau's at E » 3 V and E » 1 V (Fig. 7) correspond to the intercalation degree of 1< x <2 and 2< x <4 upon a cubic-tetragonal and tetragonal-trygonal phase transition, respectively [64, 133, 140, 196-204, 246, 300]. The identification of three distinct regions in the potential-composition (E-x) curves at makes the basis for spinel electrodes application in energy storage devices.

In the last years, several overlithiated and defect spinel phases of the general formula Li1+xMn2-xO4 (0 Ł x Ł 0,33), Li1-xMn2-2xO4 (0 Ł x Ł 0,11) or Li1+xMn2-xO4-y (0 Ł x Ł 0,33) [122, 144, 166, 177, 196, 216-219] have been used in the so-called "lithium-ion" batteries with the carbon based negative electrode [304-351]. Alternative lihium-ion batteries contain two transition metal oxides having different intercalation potentials [352-360]. Quite recently, a family of mixed spinel oxides Li[M(1+x)/2Mn(3-x)/2]O4 (-1 Ł x Ł 1; M = Co, Cu, Fe, Co, Cr) has been proposed for the positive electrode [365-377], Li[Li0,33Ti1,67]O4 as the negative electrode [354-360]. Future improvement of the charge-discharge performance of spinel electrodes for primary and secondary lithium batteries can be expected under a complex optimisation of the synthesis methods, the electrode mophology, porosity and thickness. Furthermore, the advanced batteries require the high conductivity electrolyte-solvent systems, stable in the potential range of at least 0 to 5V.


Wiadomości Chemiczne, 2001, 55, 289.
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PLATINUM AND ITS COMPOUNDS IN HUMAN ENVIRONMENT - ARE THEY DANGEROUS?

Barbara Leśniewska, Krystyna Pyrzyńska*, Beata Godlewska-Żyłkiewicz

Instytut Chemii, Uniwersytet w Białymstoku, Piłsudskiego 11/4, 15-443 Białystok
*Wydział Chemii, Uniwersytet Warszawski, Pasteura 1, 02-093 Warszawa


Platinum is widely used as a catalyst in different chemical synthesis, industrial processes, and as an active part of car catalytic converters. Platinum complexes, mainly cis-platin and carboplatin, are used as active anti-tumour agents in medicine. The toxic effect of platinum and its compounds and their influence on the occupationally exposed persons as well as different sources of platinum emission to the environment are discussed in this paper.

A continuous increase of platinum concentration in the environment could be observed over the last years [14,34,35]. The elevated level of platinum was found in soil, grass, sewage sludge, road dust (Table 3). Due to the fact that the main part (about 75%) of the anti-cancer drugs is excreted from the body several days or weeks after usage [26,27], the effluents from hospitals also contain significant platinum concentration [42,44]. Platinum of this origin could enter the human food chain by inhalation and digestion truck.

The information on the mobility, bioavailability and speciation of platinum in the environment is needed for better understanding of its environment impact and the influence on human health. The present knowledge on these problems are summarised in this review.


Wiadomości Chemiczne, 2001, 55, 331.
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INFLUENCE OF ALUMINIUM CHEMICAL ACTIVITY ON DETONATION PARAMETERS OF COMPOSITE EXPLOSIVES CONTAINING ALUMINIUM POWDERS (CX-AL)

Andrzej Maranda

Zakład Materiałów Wybuchowych i Fizyki Wybuchu, Wydział Uzbrojenia i Lotnictwa Wojskowej Akademii Technicznej, ul.S.Kaliskiego 2, 00-908 Warszawa


The earliest explosive mixtures containing aluminium powder were patented at the beginning of the 20th century. Since then, aluminium has been used in lots of successively worked up explosives designed both for commercial and military applications. It is considered that aluminium powder is an energising and sensitizing component. Howewer, the behaviour of aluminium in detonation is not well understood despite the long history of it use in explosives. Depending on dominant theories in related sciences, researchers have proposed different hypothesis describing participation of aluminium in chemical reactions in detonation waves.

In this work, some published data concerning the influence of aluminium additive on detonation velocity and composition of solid detonation products are analysed. According to classification of aluminised explosives proposed in Ref. [5], we divided the mixtures examined into high explosives sensitised composite explosives (CX-Al-1) and mixtures including crystalline oxidisers that have only slightly marked explosive properties (CX-Al-2). For instant, some results of detonation velocity maesurements for the first group are presented in Figs 1(4 and in Tables 1 and 2. They show the influence of amount of aluminium and its finenes on detonation velocity of composite explosives containing RDX, HMX, TNT or PETN. The composition of solid detonation products of CX-Al-1 explosives was the subject of researches in Ref. [18(25] and their results were the base for estimation of the degree of aluminium oxidation in detonations, Ref. [20, 22, 25]. Some of results are also analysed in this work. Figs 7 and 8 as well as Table 4 contain values of detonation velocity for explosive from the second group - CX-Al-2. The explosives included ammonium nitrate, guanidine nitrate or ammonium perchlorate as oxidisers.

On the base of the overview, a hypothetical mechanism of detonation of aluminised composite explosives is proposed. In our opinion, the effectiveness of aluminium oxidation is affected by properties of the main ingredient of an explosive.


Wiadomości Chemiczne, 2001, 55, 353.
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SEARCHING OF g-AMINO- AND g-HYDROXYBUTYRIC ACID ANALOGS WITH EXPECTED ANTICONVULSANT ACTIVITY

Barbara Malawska

Katedra Chemii Farmaceutycznej Collegium Medicum Uniwersytetu Jagiellońskiego 30-688 Kraków, ul. Medyczna 9


In the search for new anticonvulsants, derivatives of a-substituted g-amino-, g-phthalimido-, and g-hydroxybutyric acid such as acids, esters and amides were obtained [24, 25, 28, 29, 33]. Preliminary pharmacological tests, a maximal electroshock (MES) and a subcutaneous metrazole (scMet), and a rotorod toxicity assay for all synthesized compounds were employed [34, 35]. It was shown that a-substituted N-benzylamides of g-hydroxybutyric acid (GHB) were the most potent compounds and possessed anticonvulsant activities in the (MES) screens [24, 29, 33]. The most potent anticonvulsant compounds were a-(benzylamino)- g-hydroxybutyric acid N-benzylamide (39) and N-(2-chlorobenzylamide) (40) with medium effective (ED50) doses 63.0 mg/kg and 54.0 mg/kg, respectively [29]. These compounds were less active then the commonly used anticonvulsants carbamazepine and phenytoin, but had higher activity in the MES screen than sodium valproate. The preliminary biochemical tests suggest that the active amides are acted as an allosteric modulator of the g-aminobutyric acid, GABA-A complex, and have the affinity to voltage sensitive calcium channels (VSCC) receptors. It may be the possible mechanism which mediates the anticonvulsant effect of these compounds [28, 29]. Four series of N-benzylamides of GHB, which contained the N-(4-phenylpiperazine)- (series A), N-(4-benzylpiperazine)- (series B), N-benzylamino-(series C), or N-(2-phenylethylamine)- (series D), group in the a-position of GHB were selected as models to found out the structural elements and/or physicochemical properties responsible for their anticonvulsant action. The lipophilicities of four anticonvulsant active series of compounds were determined by reversed-phase thin-layer chromatography (RM value) [51, 52]. The partition coefficients (log P) of the amides were calculated by use of the Prolog P module of the Pallas system [53]. Comparison of RM and log P enabled calculation of clog P values. It was found that anticonvulsant activity of amides series A-D may be explained on the basis of their lipophilicity. In order to point to some structural features correlating with the MES anticonvulsant activity crystal structure analysis followed by conformational analysis was carried out on two compounds (21 and 29) of series A and B [33]. Molecular modelling investigations were carried out using computer program [66] on the representative compounds of series A-D. Based on the pharmacological, physicochemical, rentgenostructural and molecular modelling results the pharmacophore model for anticonvulsant N-substituted amides of GHB was design. In this model, the presence of the N-benzylamide fragment is essential for activity. For amides the further elements are hydrophobic unit (aryl ring) as a distal binding site and H-bond as a donor function. Based on this model new compounds with expected anticonvulsant activity may be design.


Wiadomości Chemiczne, 2001, 55, 377.
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NOTATKI CHAOTYCZNE. XXXIII. WIEDZA MINERALOGICZNO-CHEMICZNA W POLSCE W CZASACH BOLESŁAWÓW

Ignacy Z. Siemion

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



Wiadomości Chemiczne, 2001, 55, 403.
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GLENN THEODORE SEABORG - A CHEMIST AND PHYSICIST

Albert Ghiorso*, Darleane C. Hoffman*, Adam Sobiczewski**

*University of California, Lawrence Berkeley National Laboratory, Berkeley, USA
**Instytut Problemów Jądrowych im. A. Sołtana, ul. Hoża 69, 00-681 Warszawa



PHOTO- AND ELECTROCONDUCTING CONJUGATED POLYENES

Kazimiera A. Wilk, Beata W. Domagalska

Instytut Technologii Organicznej i Tworzyw Sztucznych, Politechnika Wrocławska, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław


The design of optoelectronic components with molecular dimensions is an area of active research and theoretical calculations. Unsaturated organic molecules containing p-conjugated bonds have been explored in connection with "molecular wires", transfer of electrons across lipid membranes, molecular mimicry of photosynthetic energy and electron transfer.

In this paper we report the most recent achievements related to synthesis and properties (i.e., spectroscopic data, intramolecular charge transfer (ICT) and electron transfer processes, thermal stability) as well as potential applications of well defined oligomeric conjugated structures derived from oligomers of acetylene; in the literature they are named conjugated polyenes. These compounds are characterized by the presence of polar end groups: the donor (D - e.g., derived from anilines, thiophenes, ferrocenes, 1,4-dithiafulvenes, julolidine moiety) with electron donating capabilities and the acceptor (A - e.g., nitro, formyl, dicyanomethylen, derived from thiobarbituric acid) able to withdraw electrons (Fig. 1, Table 1). The D and A groups are connected through a conjugated p - system (e.g., polyenic, polyaromatic or polyheteroaromatic chain). Unsymmetrical substitution of the polyene chain defines a class of push-pull polyenes and symmetrical one creates push - push or pull - pull entities. Their structural properties are the results of a subtle balance between different factors, among which of particular importance are the chain length and the donor acceptor strength (Fig. 2.).

The synthesis of polyene chains has been widely explored in literature. The most commonly employed procedure for the synthesis of conjugated spacers involves a sequence of Wittig-type reactions (Fig. 3, Table 2). The alternative, iterative building block method applies oligosililoxy ethers and tempaltes (e.g. 5,5-dietoxypenta-2-enal) to involve the polyene chain increase (Fig. 4.).

According to the literature all conjugated polyenes reveal satisfactorily high decomposition temperatures (above 230 oC) which makes them good candidates for optoelectronic devices (Tables 3 and 4).

The conjugated polyenes are of particular interest as model systems of one dimensional conjugated chromophores. It is now generally recognized that bipolaronic charge states dominate in most oxidatively doped p-electron conjugated structures with non-degenerate ground states (Fig.6). In general, all such molecules undergo a Peierls distortion, making charge transport between chain ends dependent upon thermal processes and limiting the rate of such charge transport. The use of solitonic moieties as charge carriers in molecular wires is among the initial proposals for molecular electronics (Fig. 7.). Solitons have also been suggested for use in molecular gates or switches (Fig. 8.).

The UV-VIS spectra of the D-p-A system in solution display a low energy absorption band, which is attributed to the ICT from the donor to the acceptor unit, and the efficiency of such a process modulates the physical properties of the system. Some examples are collected in Tables 5, 6 and 7.


Wiadomości Chemiczne, 2001, 55, 439.
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MODELLING OF ENZYMATIC DEPOLYMERISATION REACTIONS USING MONTE CARLO METHOD

Piotr M. Wojciechowski

Instytut Chemii Nieorganicznej i Metalurgii Pierwiastków Rzadkich Politechnika Wrocławska ul. Smoluchowskiego 23


Enzymatic processes of polymer decomposition can be very accurately modelled using both stochastic methods and deterministic methods. The main aim of this paper is to analyse various aspects of the use of both methods. The problem of expressing the concentration of each set of substrates and products as an explicit function of time, in the case of the multisubstrate system, is considered through an example of amylolytic starch hydrolysis.

The second part of this paper presents the basic concept and outline of the Monte Carlo method adopted to describe processes of enzymatic polymer degradation has been shown. The presented iteration model is probably the simplest algorithm which allows to describe both multienzymatic and multisubstate reactions giving concentration evolution of all participants in the investigated system. Action of various kinds of inhibition, enzyme inactivation, reverse reaction, single and multiple chain reactions can be accurately simulated. This method can be applied to obtain a product with desired properties. In addition, the model can be used to predict hydrolysis patterns of starch by different amylases, too.

To check the validity of the model against the experimental data the process of starch hydrolysis by mixture of three amylolytic enzymes has been simulated and the results presented. Agreement between simulated and experimental data through the course of the reaction was excellent in all the reaction stages.


Wiadomości Chemiczne, 2001, 55, 473.
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THE PROTECTING GROUPS OF THE AMINO FUNCTION IN D-GLUCOSAMINE

Dorota Bednarczyk, Henryk Myszka

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


Aminosugars widely exist as a part of biologically important natural products. They are found in some antibiotics, polysaccharides, lipopolysaccharides, glycolipides, glycoproteins and blood group determinants [1-5]. Most wide-spread aminosugars are 2-amino-2-deoxyaldoses and among them D-glucosamine. Because of its abundance of occurrence and function fulfilled, this aminosugar is often used in the synthesis of glycosides, as well as a glycosyl donor or acceptor. The methods of synthesis of glycosides have been well known for many years. The classical Koenigs-Knorr method is one of the oldest methods for the preparation of glycosides and requires glycosyl halides as donors (most often bromide or chloride) and heavy metal salts (mainly mercury and silver) as a promoter [6]. The alternative procedure is the imidate method, which requires the use of 1-O-trichloroacetimidate derivative of sugar as glycosyl donor and BF3 · Et2O or trimethylsilyl triflate as promoter [7]. Apart from these two ways, others should be mentioned, namely: the orthoester and thioglycoside method, those methods using of glycals, 1,2-anhydrosugars and pent-4-enyl glycosides [8-11]. However, these methods have been known for many years ( and still modified ( the selective synthesis of glycosides still determines the main challenge in the chemistry of carbohydrates. The course of reaction, its stereoselectivity, speed and yield depend on many factors, the most important of which seem to be: the leaving group at the anomeric carbon atom in donors, the conditioners of the reaction ( solvent, temperature, promoter and a character of the protecting groups at almost all carbon atoms ( especially at carbon C-2, as this group can constitute part of the so-called participating group in the process of creation of the glycoside bond. Description of the glycosylation mechanism can be found in many papers [6-13].

Several new amino protecting groups have been described recently, particularly for the (NH2 function in D-glucosamine. Choice of the 2-amino protecting group is very important and will have a strong influence on the synthesis of the desired glycosides. In this paper we would like to describe the most popular protecting groups. They belong to different group-types, among which we can find: (i) amides ( acetyl (NHAc) [4], trifluoroacetyl (NHTFAc) [14-20], diacetyl (NdiAc) [21, 22], pent-4-enoyl (NHPent) [23-25]; (ii) imines ( p-methoxybenzylidene (NBzlOMe) [26-31]; (iii) carbamates ( allyloxycarbonyl (NHAloc) [32-34], 2,2,2-trichloroethoxycarbonyl (NHTroc) [35-41] and other alkoxycarbonyl (NHAlkoc) [33]; (iv) cyclic imides ( phthaloyl (NPhth) [42-54], 4-nitrophthaloyl (NNP) [55-57], 4,5-dichlorophthaloyl (NDCP) [58, 59], tetrachlorophthaloyl (NTCP) [22, 25, 60-66], diphenylmaleyl (NDPhM) [67], thiodiglycoloyl (NTDG) [68] and dithiasuccinoyl (NDts) [69, 70], which are exemplified below (Figure 1).


Wiadomości Chemiczne, 2001, 55, 491.
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SWEET COMPOUNDS CONTAINING SULPHUR

Krystyna Jarzembek

Instytut Chemii Uniwersytetu Śląskiego, ul. Szkolna 9, 41-006 Katowice


The formation of the ligand-receptor complex is a complicated phenomenon. This process poses a nontrivial problem if attempted to be analyzed and described precisely. Up to now a structure of sweet receptor has not been determined. Moreover, there is still a controversy if there is one or more than one type of the sweet taste receptors [1-4].

A sweet taste is produced by a wide variety of compounds. Shallenberger and Acree [5-9] regard an acid-base system (AH/B-System) as the shared structure element. Kier [10-12] expanded this model by assuming an additional interaction with a non-polar group in a suitable position. Both models are applicable to compounds with great variations in structure. Temussi expanded this model and described a mode of interaction between sweet and bitter compounds [13-22] and a suitable receptors.

As regards synthetic sweeteners, it is surprising that each major class of this type of sweeteners has been discovered serendipitously. Many sweeteners contain sulphur or, in particular, a sulphonyl group, e.g. saccharin or its analogs [23-32], cyclamates [33-44], acesulfame-K [45, 46], arylsulfonylalkanoic acids [47-52].

In this paper, the substantial requirements limiting structure-activity relationships for sweeteners containing sulphur are reviewed and discussed.


Wiadomości Chemiczne, 2001, 55, 517.
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THE METHODS OF PREPARATION OF PHENYL-TRIFLUOROMETHYL SULFIDES

Arkadiusz Mizerski, Zbigniew Ochal

Wydział Chemiczny, Politechnika Warszawska ul. Noakowskiego 3, 00-664 Warszawa


The methods of preparation of phenyl-trifluoromethyl sulfides can be divided into three groups:
1. substitution of three atoms of chlorine in trichloromethyl sulfide by three atoms of fluorine, but it is very difficult;
2. introducing trifluoromethylsulfanyl group into benzene ring;
3. reactions between tiophenols, their salts, disulfides, sulfenyl chlorides or phenyl tiocyanides and compounds containning trifluoromethyl group.


Wiadomości Chemiczne, 2001, 55, 533.
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EFFECT OF POLYMERS ON PROPERTIES OF DISPERSIONS OF NANOPARTICLES

Waldemar Nowicki, Grażyna Nowicka

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


The stability of colloidal dispersions is often modified by addition of polymers which, depending on the conditions, can induce repulsion or attraction between particles. The repulsion contributes to the stabilization of dispersions, whereas the interparticle attraction results in the dispersion flocculation. These phenomena are of great importance in many biological, medical, environmental, and chemical industrial processes [1-23] and they attract much of scientific interest. The main mechanisms of the processes which are induced both by nonionic polymers and polyelectrolytes as well as adsorbing and nonadsorbing macromolecules, are briefly reviewed in this paper.

In the majority of systems in which stabilization/flocculation processes were studied, the colloidal particles were large, compared with the radii of gyration of macromolecules. On the other hand, it was found that interactions between very small colloidal particles and large polymer molecules are important in such areas like the water and waste water purification [46-47] and paper manufacture [48]. They also play a major role in biological systems [49-51]. The systems composed of very small particles and large macromolecules have been found to reveal a number of original features [29-30,102].

The relative size of macromolecules and particles has a significant effect on the conformation of the polymer adsorbed [43,62-84], the interparticle interaction [45] and the structure of aggregates formed [28-29,74,102]. When colloidal particles are smaller than the macromolecules then a single particle accommodates only a part of the polymer chain, the rest of the molecule extends far away from the particle as a long end which can adsorb on the free surface of other particles [43,72-76,83-84]. Multiplets composed of a number of particles attached to a single polymer molecule are formed [28-29,37,51,72,84-90,102]. Properties of these multiplets determine the phase behavior of the system; if further association takes place the macroscopic phase separation is observed, otherwise the suspension is stable [37,85-86,89,102]. Primarily, the interactions between the multiplets depend on their structures which, in turn, are determined by numerous factors like the polymer-to-particle number concentration, adsorption affinity, particle interactions, architecture and conformations of polymer molecules, and others.

A number of models of the adsorption of large macromolecules on very small colloidal particles [71-79] and the flocculation and stabilization processes of fine suspensions by high-molecular-weight polymers [94-97] were proposed.

The mode of action of very long polymer chains on fine suspensions was studied with computer simulations [91-93]. The floc structures and formation kinetics were investigated as a function of polymer/particle concentration ratio and the chain conformation.


Wiadomości Chemiczne, 2001, 55, 547.
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NOTATKI CHAOTYCZNE. XXXIV. O POCHODZENIU HOMOCHIRALNOŚCI ZIEMSKIEJ I O DICHROIZMIE MAGNETOCHIRALNYM

Ignacy Z. Siemion

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



Wiadomości Chemiczne, 2001, 55, 583.
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HYDROGEN BONDING - SELECTED PROBLEMS

Lucjan Sobczyk

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


In a short introduction the importance of hydrogen bonding is emphasized in life sciences and its role in molecular recognition and creation of living molecular systems. Then an attempt to define this specific molecular interaction is undertaken. Among most important features one should distinguish a particular repulsion potential which enables to approach directly interacting atoms on a distance markedly less than the sum of van der Waals radii. An important feature of hydrogen bonds is also the appearance of a double minimum potential for the proton motion. Among the main physical properties of hydrogen bonds there are analyzed dipole moments, nuclear magnetic resonance, quadrupole magnetic resonance, infra-red spectra and isotope effects. Most important isotope effects are related to infra-red spectra, geometry of bridges, phase transitions in hydrogen bonded ferroelectrics and fractionation factor. The evolution of the main characteristics is discussed depending on the acid-base properties expressed by means of the DpKa value of interacting components. A separate chapter is devoted to a dualistic nature of the interaction i.e. the structure creating and dynamical ones. The structure creating character is shown taking into account the induction of liquid crystalline properties while the dynamical properties are examplified on enzymic and photobiological processes and phase transitions in hydrogen bonded crystals. Current aspects of hydrogen bond interaction are limited to photoinduced proton transfer processes, the time resolved infra-red spectroscopy, low barrier hydrogen bonds (LBHB) and quantum molecular dynamics. In final remarks the importance of hydrogen bonding in searching for new materials of practical importance and crystal design are underlined.


Wiadomości Chemiczne, 2001, 55, 593.
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DENSITY FUNCTIONAL CALCULATIONS OF INTERACTION OF MOLECULAR HYDROGEN WITH TRANSITION METALS. PERSPECTIVES OF QUANTUM MODELS OF HETEROGENEOUS CATALYSIS

Witold M. BARTCZAK (a,b) , Stanisław ROMANOWSKI (a), Marcin ŁANDWIJT (b)

(a)Katedra Chemii Teoretycznej, Uniwersytet Łódzki, ul. Pomorska 149/153, Łódź
(b)Instytut Techniki Radiacyjnej, Politechnika Łódzka, ul. Wróblewskiego 15, Łódź


Computer modelling of catalytic effects of a series of the transition metals and their alloys on the process of dissociation of molecular hydrogen has been performed. The project was composed of three stages. First, the binding energy versus the internuclear distance has been calculated for a series of metal dimers and mixed dimers: Ni2, NiCu, Cu2, Ag2, AgPd, Pd2 Au2, Pt2, AuPt. It has been shown that the traditional methods of quantum chemistry: the ZINDO semiempirical methods and the Hartree-Fock methods do not work properly in the case of the transition metal dimers. In contrast with these methods, the calculations based on the nonlocal version of the density functional theory (DFT) provide very good results, in full agreement with available experimental data concerning the dissociation energies and equilibrium bond lengths of the metal dimers.

Then, using the fitted Morse form of the potential interaction between the metal atoms, the Molecular Dynamics (MD) simulations have been performed in order to obtain the atomic structures appearing in the alloys.

The third part of the project includes the quantum-chemical calculations of hydrogen atom and hydrogen molecule positioned over the metallic dimers. The interatomic distances of the dimers were taken from the MD calculations. A range of the distances of hydrogen from the metal dimers was scanned. The evolution of energy and electron density with the hydrogen distance from certain dimers, like NiCu, AgPd and Pd2, clearly exhibits the process of the hydrogen molecule dissociation. On a basis of these calculations a measure of catalytic power of the metals was defined and the series of metals and alloys was ordered according to their catalytic power. It was found that the highest catalytic power with respect to the hydrogen dissociation process is exhibited by NiCu alloys.

All the quantum-chemical calculations have been performed using the methods of the Density Functional Theory. The nonlocal version of the DFT was applied with the gradient-corrected hybrid functionals for electron exchange and correlation. The GAUSSIAN 98 suite of programs was employed in the calculations.


Wiadomości Chemiczne, 2001, 55, 629.
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ALKOXYALLENES. METHODS OF PREPARATION AND APPLICATION TO ORGANIC SYNTHESIS

Robert Łysek, Marek Chmielewski

Instytut Chemii Organicznej Polskiej Akademii Nauk ul. M. Kasprzaka 44/52,01-224 Warszawa


The present short review describes methods of preparation and synthetic applications of alkoxyallenes. The title compounds can be obtain by variety of methods based on elimination, substitution, addition, isomerization and alkylation reactions. Methods based on elimination reactions (Schemes 1-2) [4, 5] and on substitution of halogen (Scheme 3) [1], or alkoxy substituent (Schemes 4-5) [7-9] in allenes, or propargyl derivatives are not of great importance. The most important method of preparation of alkoxyallenes is based on isomerisation of propargyl ethers (Schemes 9-11) [15, 16, 18]. The rearrangement triple bond/allene offers possibility of introduction of alkyl or silyl substiuents by consecutive deprotonation-alkylation and/or silylation steps (Schemes 12-16) [20, 21, 24, 26].

Alkoxyallenes undergo readily deprotonation a to the alkoxy group by treatment with n-butyl lithium [19]. The resulting lithium salt reacts with electrophiles such as carbonyl compounds (Schemes 12, 20, 22) [19] and alkyl halides (Scheme 14) [22] to afford substituted alkoxyallenes. Subsequent hydrolysis of alkoxyallene fragment provides a,b-unsaturated carbonyl compounds (Schemes 33, 34) [19, 54-56]. 1-Alkoxy-1-hydroxyalkylallenes in the presence of strong bases gave alkoxydihydrofurans or tetrahydrofuranones (Scheme 35) [57-59]. Alkoxyallenes subjected to [4+2]-, [2+2]-, and (1,3)-dipolar cycloaddition afford variety of heterocyclic compounds (Schemes 36-40, 43-48) [26, 61-66, 75-77]. Five- and six-membered heterocycles having exo-double bond may undergo rearrangements to form more stable compounds [75].

Attractive chemical properties prompted many laboratories to use alkoxyallenes for the synthesis of natural products. Syntheses of (+)-goniodiol 58 (Scheme 23) [34], methylenomycin B 71 [39], erigerol 89 (Scheme 32) [53], (+)-allopumilitoxin 267 A 91 (Scheme 33) [55], lacramin A 158 (Fig. 3) [80], cytochalastin B 159 (Fig. 3) [81] and (±)-xanthocidin 162 (Fig. 3) [84] are the most representative.

Alkoxyallenes undergo radical (Scheme 51) [89], cationic [90] and coordination (Scheme 53) [91, 92] polymerization providing polymers having exo-methylene groups. In certain cases, alkoxyallenes may undergo spontaneous polymerization [93] or polyaddition [94].


Wiadomości Chemiczne, 2001, 55, 657.
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THERMOELECTRIC RATTLERS:COMPOUNDS WITH STRUCTURE OF FILLED SKUTTERUDITE

Wojciech Suski

Instytut Niskich Temperatur i Badań Strukturalnych im. W. Trzebiatowskiego, PAN, skrytka pocztowa 1410, 50-950 Wrocław 2
Międzynarodowe Laboratorium Silnych Pól Magnetycznych i Niskich Temperatur, ul.Gajowicka 95, 53-421 Wrocław


In a brief introduction a general description of thermoelectricity, thermoelectric materials and their characteristics, and early investigation are given. Then the skutterudite structure is discussed with the emphasis on the atomic displacement parameters (ADP). The presented properties concern magnetism, superconductivity as well as the behavior indicating the presence of strongly correlated electronic states in some skutterudites. Particular attention is devoted to the heavy fermion and non--Fermi liquid states, and intermediate valence. Finally, some remarks about band structure and perspective of improving the thermoelectric properties of the filled skutterudites are considered.


Wiadomości Chemiczne, 2001, 55, 693.
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COMBUSTION OF MIXTURES OF METALS WITH FLUOROCARBON POLYMERS

Stanisław Cudziło

Wydział Uzbrojenia i Lotnictwa, Wojskowa Akademia Techniczna ul. S. Kaliskiego 2, 00-908 Warszawa


The main aim of the paper is to overview recent works dedicated to miscellaneous aspects of combustion process of metal- fluorocarbon polymer formulations. In order to systematise the collected data, the article is divided into sections discussing consecutively: mechanism of the combustion process and factors determining the linear burning rate, thermal decomposition of the mixtures, their sensitivity to mechanical, thermal and laser stimuli, emission characteristics of the flame accompanying combustion, problems concerning their stability and ageing process, and their application forms of military interest.

Metal-fluorocarbon polymer compositions are heterogeneous high-energetic materials in which the burning rate is strongly dependent on the metal particle sizes (f) and the concentration of metal (x) in the mixture [8-16]. The oxidation reaction of metal particles is considered to occur from the surface of each particle and propagates towards its centre (Figs 1, 6). If the total burning surface area of the metal particles is small, the reaction completes at far downstream of the propellant burning surface. Therefore the heat flux feedback from the gas phase to the front of the combustion wave and, consequently, the burning rate rise when x increases and f decreases (Figs 2-5 and 7-9). By using metals that melt down at a temperature below the PTFE decomposition temperature (770 K), it is also possible to facilitate the initiation and propagation of the combustion wave in the compositions in question (Figs 5, 8, 9) [12, 13, 16].

Applying different methods of thermal analysis to study the decomposition of PTFE in the presence of some metals, it has been shown that an addition of Mg, Al, Al3Mg4, Ti, B, Zr causes the purely endothermic decomposition of PTFE in nitrogen and argon to develop exotherms with onsets in the temperature range 740(770 K (Tab. 3, Figs 12, 13). As the amount of a metal increases these exotherms enlarge whereas the decomposition endotherm is reduced in size (Fig. 11).

Size of Mg particles and its concentration in a MTV mixture affects not only the burning rate and decomposition parameters, but also the sensitivity of the mixture [11]. MTV compositions seem to be quite sensitive to impact and their sensitivity increases with increasing burning rate [21]. On the other hand, they have low sensitivity to friction (Tab. 5) [22] and do not produce a hazardous response while being heated under typical cookoff conditions (Tab. 6) [23].

PTFE is an exceptionally good oxidiser in composition designed for producing high radiation output in the IR region (Tab. 7) [25, 26, 35, 36]. MTV compositions display functional relation between stoichiometry and specific intensity of radiation in 2-3-mm and 3-5-mm bands (Fig. 16). With rising weight fraction of Mg up to 60 % the specific intensity increases. For values of x>60 %, the radiation output decreases [26, 36]. Infrared tracking flares are the main direction of military applications of MTV formulations [4, 35, 36]. The latest patent in the field claims an IR-emitting flare composition comprising about 54(58 % of Mg and the remainder a mixture of PTFE and polytrifluorochloroethylene in substantially equal amount [36]. This mixture is superior to prior-art flares (Tab. 11, Fig. 21).

Ageing of MTV is caused by the reaction of magnesium with water into magnesium hydroxide and hydrogen. This reaction continues until all Mg is converted into Mg(OH)2 (Tab. 8, Fig. 17). The burning characteristics, the maximum pressure and in particular the burning time are changed with respect to unaged pellets (Fig. 18). These changes greatly affect the performance of the compositions [27].

Because of important advantages of MTV mixtures as a relative high caloric output, strong radiant output, generation of multiphase reaction products, low gas output, these compositions are used as igniters for solid rocket motors and other pyrotechnics. A general conclusion that can be made on the basis of the papers [27-33] is that metal rich compositions (containing 60(65 % Mg) perform better than other ones.

Finally metal-PTFE formulations are a perfect solution for composite pyrotechnic mixtures in which presence of oxygen is undesirable. Such a situation takes place in compositions producing clouds rich in soot particles [37, 38] or in smoke-generating mixtures based on red phosphorus [39, 40].


Wiadomości Chemiczne, 2001, 55, 715.
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ARYLPIPERAZINE LIGANDS OF SEROTONIN (5-HT)1A / 5-HT2A RECEPTORS

Ewa Chojnacka-Wójcik

Zakład Badań Nowych Leków, Instytut Farmakologii PAN, ul. Smętna 12, 31-343 Kraków


Recently some interest has focused on compounds which - through interaction with both 5-HT1A and 5-HT2A receptors - may act as potential psychotropic agents [10]. Compounds with a dual activity at these receptor systems have been predicted to be more efficacious than those acting at only one of these systems. Some such compounds are arylpiperazine derivatives. This is the case with flibanserin and adatanserin, regarded as 5-HT1A agonists and 5-HT2A antagonists [11-13,16-22], which show an robust activity in a number of animal models of anxiety and depression [14-16,19,23]; at present they are studied in the clinic as potential anxiolytics/antidepressants [10]. Another arylopiperazine, ziprazidon, binds with a high affinity to 5-HT1A, 5-HT2A and D2 receptors [8,24]; being an antagonist at the latter receptors, it behaves like a 5-HT1A agonist [25]. Ziprasidon is a novel antipsychotic drug [10].

In our own studies, a number of new arylpiperazines with high 5-HT1A / 5-HT2A [26-30] and D2 [30] affinity were obtained. In fact, 1-{3-[4-(3-chlorophenyl)-1-piperazinyl]propyl}-6-fluoroindolin-2(1H)-one (1) and 1-{3-[4-(2-methoxyphenyl)-1-piperazinyl]propyl}-6-fluoroindolin-2(1H)-one (2) demonstrated a high 5-HT1A / 5-HT2A affinity and an in vivo antagonistic activity towards both the receptor subtypes, a phenomenon which is probably connected with the presence of a tree-membered spacer beetween terminal molecule fragments [26]. Also 1-{3-[4-(3-chlorophenyl)-1-piperazynyl]propyl}-2,4-benzoxazin-3(4H)-one (3) showed the same pharmacolo-gical profile of action. It has been suggested that the oxygen atom in position 2 in the amide fragment, as well as the 3-[4-(3-chlorophenyl)-1-piperazinyl]propyl fragment are a prerequisite for its pharmacological properties [27]. The new 1-(3-chlorophenyl) piperazine derivative of 1,3-benzoxazolin-2,4-dione with n-butyl chain (4) may be qualified as a 5-HT1A partial agonist and 5-HT2A antagonist; its 5-HT1A functional activity is likely to be connected with the character of the amide fragment, whereas the 1-arylphenyl fragment is important to the binding to both receptors [28]. The connection of the 1,2,3,4-tetrahydro-b-carbolin-1-one moiety - through the 2-4 membered alkyl spacer - with 1-(2-methoxyphenyl)-piperazine permitted us to obtain compounds (5-7) with a high and an equal affinity for 5-HT1A / 5-HT2A receptors and with the expected functional properties, i.e. a distinct antagonistic activity at 5-HT1A receptors and an antagonistic one at 5-HT2A ones. These findings corroborate hypothesis that the presence of the 1-arylpiperazine fragment is crucial to the 5-HT1A / 5-HT2A affinity [29]. It has also been shown that 3-chloro (8) and 2-methoxy (9) derivatives of 1-[4-(4-aryl-1-piperazinyl]-3,4-dihydro-2(1H)quinolinones are potent antagonists of 5-HT1A / 5-HT2A/D2 receptors and resemble some atypical antipsychotics [30].

Summing up, some of the new investigated arylpiperazines may be considered as novel agents with psychotropic (i.e. anxiolytic/andidepressant/antipsychotic) properties.


Wiadomości Chemiczne, 2001, 55, 751.
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NOTATKI CHAOTYCZNE. XXXV. WIKTOR VON RICHTER - PIERWSZY NA ZIEMIACH POLSKICH RZECZNIK IDEI MENDELEJEWA

Ignacy Z. Siemion

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



Wiadomości Chemiczne, 2001, 55, 773.
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NEW NATURAL PRODUCTS WITH CYTOSTATIC ACTIVITY

Agnieszka Gryszkiewicz, Izabella Jastrzębska, Jacek W. Morzycki

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


Secondary metabolites of marine invertebrates continue to attract attention of organic chemists, biochemists, and pharmacologists due to their interesting structures and potent biological activities. One such example is cephalostatin 1 (Scheme 1) isolated from the Indian Ocean hemichordate Cephalodiscus gilchristi, which exhibited remarkable cytotoxic activity against a broad spectrum of malignant tumor cells [5]. Similar marine alkaloids (e.g. ritterazine G: Scheme 2) were found in the lipophilic extract of the tunicate Ritterella tokioka collected off the coast of Japan [7]. These very potent compounds, cephalostatins and ritterazines, belong to the large family of trisdecacyclic pyrazines consisting of two steroid units. The two steroid halves of cephalostatin 1 and other highly cytotoxic members of the family are different. The biological activity of the dimeric steroid-pyrazine marine alkaloids and their limited availability coupled with the new and intriguing structure make them an attractive challenge for the synthetic organic chemists [4]. A few years ago a group of cholestane glycosides (Scheme 19) was isolated from the bulbs of Ornithogalum saundersiae [8], a species of the lily family without any medicinal folkloric background. The major component of the mixture of saponins, OSW-1, exhibited sub-nanomolar antineoplastic activity [35]. While OSW-1 is exceptionally cytotoxic (Table 1) against various tumor cells, it showed little toxicity to normal human pulmonary cells. The cytotoxicity profile of OSW-1 against different cancer cell lines was found to be surprisingly similar to that of the cephalostatins, which appears to imply a related mechanism of action [36]. In this review article the synthetic efforts towards these compounds are described. One of the key features of any attempted synthesis of bis-steroidal pyrazines is the central heterocyclic ring. The classical method of pyrazine synthesis (Schemes 3-7) involves the dimerization of a-amino ketones [13]. An obvious disadvantage of a-amino ketones dimerizations is their unsuitability for unsymmetrical cross-coupling. Various methods for preparation of unsymmetrical pyrazines (Schemes 9-10) were developed [21-23]. However, the preparation of suitably functionalized steroid units is still an uphill challenge, although a significant progress in this endeavor was achieved. This is exemplified among others by the synthesis of cephalostatin 1 (Schemes 14-17) [26]. The highly active "interphylal" hybrid analogues, ritterostatins and ornithostatins (Scheme 18), were also obtained [42]. Since saponin OSW-1 contains a relatively simple steroid skeleton, it is an attractive synthetic goal. The synthesis of the OSW-1 aglycone [36, 38], and later the saponin OSW-1 (Schemes 20-24) [37], was successfully accomplished. The mode of action of OSW-1 and of the cephalostatin family is not known yet, but it seems that an oxocarbenium ion (Scheme 25), which could be generated from both types of compounds, is the likely intermediate responsible for their cytotoxicity [42].


Wiadomości Chemiczne, 2001, 55, 793.
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CYCLITOLS

Ryszard Frankowski, Wojciech Maszewski i Zygfryd Smiatacz

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


Cyclitols constitute important structural elements of a variety of biologically active compounds, such as aminoglycosides antibiotics, phospholipid inositols referred to as "secondary messengers", and coordination compounds with metals, e.g. platinum, interest in many areas of natural sciences. In spite of the fact that cyclitols have been known since the 18th century, the majority of significant achievements in this field is seen during the late 90-ties of the 20th century.

The first section of this review deals with general information on the nomenclature, structural features ([2-6]; Schemes 1 and 2), configuration ([6, 7]; Schemes 3 and 4) and conformation ([8]; Scheme 5; Table1) of the cyclitols.

The second section is concerned with the occurrence (Table 2) and biological properties of the inositols, in particular of myo-inositol and its derivatives (Schemes 7 and 8). A mechanism of action of myo-inositol 1,4,5-triphosphate (1,4,5-IP3) as a secondary messenger has been outlined in Scheme 9.

The third section discusses the occurrence and biological activity of the other cyclitols of structures illustrated by the formulae in Schemes 10 through 15.

The fourth section is confined to aminocyclitols antibiotics. Their names occurrence, mode of action and formulae of main representatives of this class of compounds are summarized in Table 3 and in Figs. 1 through 8.

The last section descibes common methods of preparation of the cyclitols. These are as follows:
(i) syntheses using sugar precursors ([40, 48]; Schemes 16-21);
(ii) syntheses utilizing the Diels-Alder cycloaddition ([52]; Schemes 20 and 22);
(iii) hydrogenation of polyhydroxybenzenes [53, 54];
(iv) molecular modification of known cyclitols ([55]; Scheme 24).


Wiadomości Chemiczne, 2001, 55, 821.
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ALTERNATIVE MEDIATORS OF MITSUNOBU REACTION

Bogdan Falkiewicz1, Kazimierz Wiśniewski2, Aleksandra S. Kołodziejczyk3

1 Katedra Biotechnologii, Międzyuczelniany Wydział Biotechnologii Uniwersytetu Gdańskiego i Akademii Medycznej w Gdańsku, Kładki 24, 80-822 Gdańsk
2 Ferring Research Institute, San Diego, CA, USA
3 Katedra Chemii Organicznej, Wydział Chemii, Uniwersytet Gdański, Sobieskiego 18, 80-952 Gdańsk


The Mitsunobu reaction is a versatile method for the alkylation of various Bronsted-Lowry acids (HA) by alcohols, proceeding in neutral media in a presence of the redox system which traditionally consists of diethyl azodicarboxylate (DEAD, Fig. 2.1) and triphenylphosphine (TPP, Fig. 3.1). The reaction proceeds probably along the generally accepted path shown in Fig. 1. The key step of the process proceeds according to the SN2 mechanism and results in one of the most useful attributes of the reaction, namely complete configurational inversion at the carbinol carbon (details of the mechanism and applications of the reaction can be found in reviews: [2-8]).

The reaction, however, has a serious limitation - the acidic component has to have pKa smaller than 13 for the reaction to proceed smoothly. Moreover, the classical methodology of the reaction suffers from low yields when applied to secondary alcohols [32].

In recent years, in order to overcome these drawbacks and expand the versatility of the original combination of the Mitsunobu mediators, significant progress in the reaction methodology has been made, mainly due to the work of Tsunoda and Itô. Two types of new mediators have been developed to replace the azodicarboxylate-TPP system. The first one is an N,N,N',N'-tetrasubstituted azodicarboxamide (Fig. 4) - tributyl phosphine (Fig. 3.2) system. All azodicarboxamide derivatives were found to be more efficient than traditional DEAD in the Mitsunobu reaction, especially for less acidic HX. N,N,N',N'-Tetramethylazodicarboxamide, TMAD, gives the best overall results among acyclic amides [20], whereas 4,7-dimethyl-3,5,7-hexahydro-1,2,4,7-tetraazocin-3,8-dion, DHTD (Fig. 4.4), in combination with TBP was found to be unique in mediating the formation of the C-C bond with sec-alcohols at room temperature [24,29]. The other type of new mediators in the Mitsunobu reaction, structurally based on betaine (Fig. 5), is cyanomethylenetrialkylphosphorane (e.g. CMBP, and CMMP, Fig. 6) [26]. The phosphorane reagents are generally less active at room temperature, but in higher temperatures they are, esp. CMMP, better than DHTD-TBP and afford satisfactory alkylation of secondary alcohols. Furthermore, the phosphorane reagents mediate the reaction of acids of pKa up to 23.5 [33]. Comparative studies of the C-alkylation revealed the general reactivity of new mediators as TMAD-TBP ( DHTD-TBP ( CMBP ( CMMP [31].


Wiadomości Chemiczne, 2001, 55, 849.
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ORGANOSILICON DERIVATES OF B-DIKETONES - SYNTHESIS, PROPERTIES AND MAIN APPLICATION

Włodzimierz Urbaniak

Wydział Chemii Uniwersytetu im. A. Mickiewicza, ul. Grunwaldzka 6, 60-780 Poznań


Organosilicon derivatives of b-diketones of a general formula (1) have a wide range of possible applications, mainly because of the presence of b-diketonate moiety showing excellent properties of metal ion chelation and relatively easily undergoing conversion to other groups, as shown in Scheme 1. A particularly interesting subject of study are the compounds whose substituent R contains silyl groups (see formula (3)), capable of reacting with surface hydroxyl groups of inorganic support, e.g. silica, or of formation of polysilioxane polymers, as shown in Scheme 2.

In the paper, two most often used methods of synthesis of this group of compounds: hydrosilylation and halogen substitution are discussed on the example of derivatives of acetylacetone, the most common representatives of 1,3-diketones.

Catalytic hydrosilylation of the derivatives containing unsaturated carbon-carbon bond in the substituent is usually non-selective and proceeds on both -C=C- bond and carbonyl groups. More effective method is substitution of halogens in the organic group of an appropriate organosilicon compound, usually of the type described by formula (15). This reaction is also non-selective, since besides the desired products of C-alkylation a substantial amounts of the products of O-alkylation appears. However, a careful choice of solvents and other reagents e.g. a considerable amount of NaI, increases the selectivity towards the C-alkylation products and allows obtaining them in high yields.

In the article the problems related to the products purification and identification by spectroscopic methods are also presented.

All the applications of organosiica derivatives of b-diketones presented in Scheme 5 are based on the use of the support modified with b-diketonate moiety.

Exemplary applications of the support modified with b-diketonate moiety for immobilisation of amino acids and metal ions are discussed in detail. The immobilised metal complexes have been applied as stationary phases in gas chromatography and as the starting material for composites containing nanometer-sized metal particles of a controllable and uniform size in an inorganic matrix for magnetic and electronic applications and for use as heterogeneous catalysts or oxygen absorbers.


Wiadomości Chemiczne, 2001, 55, 859.
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Enzymatic degradation of halogenated organic compounds

Andrzej Lewandowicz

Instytut Techniki Radiacyjnej, Wydział Chemiczny, Politechniki Łódzkiej, ul. Żeromskiego 116, Łódź


Degradation of the halogenated organic compound poses ecological, sanitary, as well as synthetic, and other problems. Enzymatic degradation of these compounds seems to be a promising option.

There are many natural sources of the chlorinated organic compounds, as well as those connected with human activity. The first source dominates [1]. However, human production cannot be ignored, however, due to the considerable toxicity of the compounds produced and their dissemination [2].

The mechanisms, by which enzymes called dehalogenases catalyze halogen-carbon bond breaking varies. Dehalogenases following different pathways were isolated from many microorganisms [20-48, 55-58]. Their substrates are usually involved in halorespiration processes, so dehalogenation is involved in carbon source and energy supply, as well [21-22, 27, 39]. Moreover, cometabolic dehalogenation is possible [106, 125-133]. Dehalogenases are also present in mammals. For example, iodine dehalogenases (so called deiodinases) are necessary for thyroid hormones homeostasis [15, 52-56].

Hydrolytic dehalogenases are currently the most studied among all classes of dehalogenases. They include such unusual enzymes as 4-chlorobenzoil-CoA dehalogenase [88-95], which is capable of breaking chlorine - aromatic carbon bond under room temperature and neutral pH, and fluoroacetate dehalogenase, which cleaves the carbon-fluorine bond [81-87]. For some of these enzymes three-dimensional structures are available now and mechanistic details have been studied [85, 93, 103-106, 123]. This contribution summarizes the present knowledge of enzymatic catalysis of this unusual chemical processes with special consideration on reaction mechanism of the best known hydrolytic dehalogenases [73-123].


Wiadomości Chemiczne, 2001, 55, 883.
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STUDIES ON SOLUTION UV-VIS SPECTROSCOPY OF TRANSITION METAL COMPLEXES WITH SCHIFF BASES.

Krzysztof Kurzak, Iwona Kuźniarska-Biernacka

Zakład Problemów Teoretycznych Chemii Nieorganicznej, Instytut Chemii, Akademia Podlaska, ul. 3-go Maja 54, 08-110 Siedlce


Metal complexes derived from Schiff bases have been known for one hundred years. The complexes have occupied a central role in the development of coordination chemistry. This situation is manifested by huge number of publications ranging from the physicochemical to biochemical relevant studies of these complexes. The reason for this sustained interest in those compounds are undoubtedly many but important among them must be their general ease to preparation, and diverse properties, e.g., their ability to reversibly bind oxygen, catalytic activity, photochromic and thermochromic properties.

Schiff base are those compound containing the azomethine group (-RHC=N-) and usually formed by the condensation of amine with carbonyl compound. Bases which are effective as coordinating ligands bear a functional group, usually -OH, sufficiently near the site of condensation that a five- or six membered chelate ring can be formed upon reaction with a metal ion. Tautomeric equilibrium of three tautomers is possible for Schiff base compounds: imine, enamine and keto-imine. The presence of the imine and enamine tautomeric forms depends on the formation of intramolecular hydrogen bond. It is claimed that enamine form is dominant in napthaldimines while imine form in salicylaldimines. The distribution of the tautomeric equilibrium is strongly depend on the solvents. The presence of keto-imine form is insignificant for Schiff base compounds, but is found in the case of b-diketones and arylimines of b-ketoethers.

The most significant complexes of the salicylaldimines are of the types: bi-, tri- and tetracoordinateSchemat 3. The geometry of Schiff base complexes depends on substituent at the coordinating nitrogen atoms. For tetra-coordinate copper(II) complexes different types of geometry is possible. A planar structure has been established for the copper(II) complexes (with bidentate Schiff base) where the substituent is hydrogen atom, hydroxyl, methyl, n-butyl or n-amyl group. In the other hand the copper(II) complexes where the substituent is isopropyl or tert-butyl are pseudo-tetrahedral.

For tetra-coordinate cobalt(II), either a square-planar or pseudo-tetrahedral geometry is possible. A pseudo-tetrahedral structure has been established for the cobalt(II) complexes (with bidentate Schiff base) where the substituent is n-propyl, isopropyl, n-butyl, tert-butyl, cyclohexyl or aryl group. Cobalt(II) complexes with bidentate Schiff bases where the substituent is hydrogen atom or hydroxyl group have a planar geometry, because of formation hydrogen bonding between hydrogen (from hydroxyl group) and oxygen (from aldehyde linkage). Geometry of this type is characteristic for cobalt(II) complexes witch Schiff base tetradentate (e.g., with salicylidene-ethylenediamine).

The aim of this account is to summarize the result of studies of structural and spectroscopic properties on Schiff bases and their complexes. These have been reviewed based on 104 articles.


Wiadomości Chemiczne, 2001, 55, 913.
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MODES OF ON-CAPILLARY SAMPLE CONCENTRATION IN HIGH PERFORMANCE CAPILLARY ELECTROPHORESIS

Angelika Mrass, Edward Bald

Zakład Chemii Środowiska, Katedra Technologii Chemicznej i Ochrony Środowiska, Uniwersytet Łódzki, ul. Pomorska 163, 90 - 236 Łódź


High performance capillary electrophoresis (HPCE) [1-6] was born of the marriage of the powerful separation mechanisms of electrophoresis with the instrumentation and automation concepts of chromatography and it has developed into an exciting and extremely powerful analytical technique in recent years. Numerous advantages, such as rapid analysis times, high separation efficiencies, low consumption of chemicals and simplicity of the instrument makes HPCE competitive to other separation techniques. One of the greatest advantages is its diverse application range, mainly due to a numerous modes of separation. Originally considered primarily for the analysis of biological macromolecules, it has proved useful for separations of compounds such as amino acids, vitamins, pesticides, inorganic ions, organic acids, dyes, surfactants, peptides and proteins, carbohydrate, oligonucleotides and DNA restriction fragments, and even whole cells and virus particles. Moreover HPCE makes the separation of chiral compounds possible.

However one restraint of the HPCE techniques is the low concentration sensitivity as a consequence of limited optical pathlength for directed on-capillary photometric detection (the most popular HPCE mode of detection) and the limited volume of sample solution that can be injected into the capillary. Therefore one of the greatest challenges in the area of HPCE methods development is to lower limits of detection (LLD) which is at least an order of magnitude higher than in high performance liquid chromatography (HPLC).

Several on-line strategies have been demonstrated to decrease LLD in HPCE, like introducing detector cell with extended pathlenth [7-11], powerful detectors i.e., laser-induced fluorescence [12,13], on-line preconcentrators with the use of solid-phase extraction materials, coated/impregnated membranes [14] or ion-exchange flow injection system coupled to capillary electrophoresis [15].

Among different remedies, on-capillary concentration techniques are easy to apply and do not require alteration of HPCE instrumentation, which are isotachophoretic preconcentration, sample stacking ( originally developed for ionic compounds, and recently introduced for micellar electrokinetic chromatography (MEKC) sweeping technique.

Mechanisms of concentration in diverse techniques are different. The concentration effect in isotachophoresis (ITP) relies on the adjustment of the concentration of the dilute sample to the higher concentration of the leading electrolyte [16-19]. Preconcentration by ITP can be performed online [20-22] or in coupled columns [23-27]. In sample stacking [28-33], the concentration effect relies on the difference in electrophoretic velocities between the high- and low-conductivity zones (background electrolyte and sample zones, respectively). Sample stacking technique can be performed in CZE [34-50] as well as in MEKC [51-63] mode. From 10 to more than 1000-fold improvements in detector response have been documented. Sweeping [64-68], a new concept in MEKC, is defined as the picking and accumulating of analyte molecules by pseudostationary phase that enters and fills the sample zone upon application of voltage. As on-capillary concentration technique, it has provided more than 5000-fold increases in detection sensitivity. Recently developed a cation-selective exhaustive injection and sweeping technique [69] improves peak heights of cation analytes a million-fold.


Wiadomości Chemiczne, 2001, 55, 933.
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NOTATKI CHAOTYCZNE. XXXVI. ZMIENNE FATA PYTAŃ KARDYNALNYCH

Ignacy Z. Siemion

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



Wiadomości Chemiczne, 2001, 55, 955.
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RADIATION CHEMISTRY AND ORIGINS OF LIFE ON EARTH

Zbigniew Paweł Zagórski

Zakład Chemii i Techniki Radiacyjnej, Instytut Chemii i Techniki Jądrowej, ul. Dorodna 16, 03-195 Warszawa


Radiation chemistry, i.e. the chemical changes initiated by the absorption of ionizing radiations, have to be considered in three chapters of discussions on the mechanisms of origins of life on Earth.

i: Much higher level of ionizing radiations on Earth than now, has given rise to intensive radiation chemistry. It played an important rôle in the formation of prebiotic organic compounds, by the abstraction of electrons from simple compounds, and leaving positive species, also very reactive. In the subsequent processes, free radicals were formed, which created new combinations and even the formation of compounds of increased molecular weight; chemical chain reactions were also initiated, all entirely at ambient temperature. However, all these reactions were not chiral in their nature, and, as far as the experiments indicate, were not able to replicate or to be amplified.

ii: In the stadium of the creation of life in the "soup" formed by different variations of high energy chemistry, radiation chemistry does not seem to be important. In spite of initial great hopes, created by physicists, the reactions initiated by ionizing radiations were of low enantioselectivity i.e. were not able to enrich one of the enantiomere, or amplify effects which could appear initially. In particular, the hopes laid in the role of the violation of parity, e.g. in the case of b-radiation, as the force promoting chirality, were not fulfilled [c.f. 16].

iii: In the lack of reasonable mechanisms for the origins of life on Earth, many researchers are looking for origins of life from the outside of the Earth. However, that approach does not solve the problem of chiral synthesis and creates additional problems of the transportation of living matter. In that respect the radiation chemistry and its biological consequence - radiobiology is univocal: ionizing radiations, filling the universe, of action extended for years, cause total inactivation of every life, even the primitive one, like in the shape of viruses. The main destructive chemistry is dehydrogenation of live organisms and dry spores, which occurs even at low temperatures, close to absolute zero. Much lower doses, of single Gy (grays) to the whole body are sufficient to destroy the human life, already during the travel to and back from Mars. The shielding atmosphere of gases around the Earth is equivalent to 10 meters thick layer of concrete. A construction and operation of a ship, which could secure the survival of the crew, by making conditions of radiation background as safe as on Earth, is impossible. For the same reasons, radiation chemistry excludes the arrival of "aliens", E.T. etc on Earth. Radiation chemistry does not exclude the possibility of Life in any part of the Universe, sufficiently shielded, but shows impossiblity of the transportation of live precursors of our life to the Earth. The Life on Earth originated here and any models of its formation, if true, have to be a subject of reconstruction in the laboratory.


Wiadomości Chemiczne, 2001, 55, 965.
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BIOFLAVONOIDS AS NATURAL ANTIOXIDANTS

Jadwiga Wilska-Jeszka, Anna Podsędek

Instytut Biochemii Technicznej, Politechnika Łódzka, ul. Stefanowskiego 4/10, 90-924 Łódź


Flavonoids are a large group of naturally occurring phenolic compounds widespread in plant kingdom. Over 4000 chemically unique flavonoids have been identified in plants. They are categorised into classes depending on the structure of the central heterocyclic ring (table 1) and within each class according to the hydroxylation pattern or other substitutents.

Since many years flavonoids are known to display different pharmacological and biological activities, but the most important is capillary protective effect and antioxidant activity. Recently increasing attention is focused on flavonoids as natural antioxidants.

A number of highly reactive oxygen species (ROS) such as singlet oxygen 1O2 and radicals: O2-·, ·OH, ·OOH, NO· as well as alkyl peroxyl free radicals are regularly produced in our body. They damage lipids, proteins and DNA and participate in pathogenesis and aging. Organism possess a wide array of antioxidant physiological defences. However in situation of oxidative stress additional exogenous antioxidants are needed to limit damage in biological systems. The natural antioxidants such as ascorbic acid, tocopherols, carotenoids and flavonoids contribute to this defence.

The recent increase of interest in antioxidant activity of flavonoids is due to their ubiquitous presence in fruits and vegetables as well as in tea, wine and beer. The dietary intake of flavonoids - 25mg to 1g/days far exceeds that of vitamin E and carotenoids [6]. However, the antioxidant activity of different flavonoids differs so much that their composition is much more important than the total content.

Flavonoids are able to scavenge ROS and alkyl peroxyl radical due to their electron donating properties. The position and degree of hydroxylation is of primary importance for antioxidant activity of flavonoids (table 3). Tea and wine are very rich in flavonoid compounds and their antioxidant activity is well documented by different laboratories [17,19,30-38].

However there has been extensive debate over the last few years on the biological significance in vivo of flavonoids antioxidants activity. Nearly nothing of ingested compounds survives in the body, as they are largely metabolised by tissues or by the colon microflora. In human plasma quercetin is mostly present as conjugate derivatives such as glucoronides and sulphates [6,40,42,43]. It is not clear what is the antioxidant activity of flavonoids metabolites, as well as their real effectiveness in organism. So one should be careful with conclusion concerning flavonoids effectiveness in vivo, on the basis of their antioxidant activity determined in vitro.


Wiadomości Chemiczne, 2001, 55, 987.
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THE INFLUENCE OF REDUCTION TEMPERATURE ON THE SORPTION AND CATALYTICAL PROPERTIES OF SUPPORTED METALIC SYSTEMS.

Stanisław Karski, Iwona Ludomirska, Izabela Witońska

Instytut Chemii Ogólnej i Ekologicznej Politechniki Łódzkiej, ul. Żwirki 36, 90 - 924 Łódź


Supported noble metal catalysts are used in a large number of commercially important processes, including hydrogenation and dehydrogenation, naphtha reforming and automotive exhaust catalysis. It is a well-known fact that support influences the catalytic activity and the selectivity of the supported metal particles. The most striking effect is the so-called strong metal - support interaction (SMSI) in which a metal / support catalyst is reduced at a high temperature (773 K) and the metal loses, at least partially, its chemisorptive properties with respect to H2 and CO. This effect was first discovered by Tauster at al.[2, 3] on titania and then extended to other reducible supports [20, 21].

Several explanations have been given to account for the loss of chemisorptive and catalytic properties: the occurrence of an electronic effect with an electron transfer between the support and the metal particles [76, 101-103, 105, 109, 110, 125], the formation of intermetallic compounds [66, 70], and the decoration of the metal by support mobile species [51, 60, 61, 64, 67, 69]. Another model describing the metal - support interaction and based on theoretical calculations suggests that the electron density in small metal particles is shifted toward nearby cations of the support [112]. Recently a new model has been proposed, in which the decrease in the activity of metal clusters can be ascribed to a decrease in the ionization potential of the metal particles which is directly induced by the Coulomb potential of the support [127].


Wiadomości Chemiczne, 2001, 55, 1005.
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SPECTROSCOPIC STUDIES OF HETEROPOLYANIONS AND THEIR COMPLEXES WITH LANTHANIDE(III) IONS

Stefan Lis, Sławomir But

Wydział Chemii Uniwersytetu im. A. Mickiewicza, ul Grunwaldzka 6, 60-780 Poznań


Polyoxometalates (POM) form a unique class of compounds of special properties with wide applications [1, 2]. Chemistry of POM is an important subarea of modern inorganic chemistry. In continuation of our earlier work, published in this journal [2], we present here studies on spectroscopic characterisation of POMs and their lanthanide(III) complexes (Ln/POM).

A nomenclature system including trivial and systematic names, reflecting information on composition and structure of POM is shortly described. Methods of synthesis of polyanions having inorganic and organic counter cations and results of studies related to POM structure and their Ln(III) complexes are briefly reviewed. Useful techniques for the verification of POMs and Ln/POM compositions and determination of components [37, 44, 46], including elemental and thermogravimetric analysis, IR and Raman spectroscopy [37, 44, 46] as well as the new spectrophotometric methods for determination of tungsten and molybdenum [18] and for simultaneous determination of these elements [39] in structures of POMs and their Ln/POM complexes are presented. An important role of the FTIR spectra (Fig.3) in characterisation of POMs and LnPOM complexes is shown [40]. Forms of POM complexes such as: sandwiched Ln(POM)2, encapsulated within the cavity of the POM and Ln2POM were studied with the use of absorption spectra (in the Nd(III) hypersensitive band (Figs. 4 and 5) and Eu(III) luminescence spectroscopy [31, 38, 40, 41, 44]. Luminescence (excitation and emission) spectra and luminescence lifetime measurements, recorded for Eu(III) complexes in solid and aqueous solutions at room temperature (Tab. 1), and luminescence quantum yield of Eu(III) ion, were used for characterisation of the species [38, 40, 41]. Influence of ionic strength on the complex formation in solution is also presented [41]. The use of EPR method to study magnetic properties and symmetry of the Gd/POM complexes is discussed. Studies shown that Gd(III) ion can be useful as a probe to study of a local environment of the host metal site in terms of symmetry and coordination in Gd/POM [42, 43].


Wiadomości Chemiczne, 2001, 55, 1029.
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LIPOPHILICITY, METHODS OF DETERMINATION AND ITS ROLE IN BIOLOGICAL EFFECT OF CHEMICAL SUBSTANCES

Krzysztof Jóźwiak, Halina Szumiło, Edward Soczewiński

Katedra Chemii Nieorganicznej i Analitycznej Akademii Medycznej w Lublinie, ul. Staszica 6, 20-081 Lublin


In this review the current concepts of lipophilicity phenomenon are described. It especially deserves special attention in medicinal chemistry. Lipophilicity is the factor of crucial importance in biological action of chemical substances. It is the main physico-chemical determinant influencing the bioavailability, permeability and frequently the toxicity of drugs. Lipophilicity is thus one of the most important factors in research aimed at rational designing of new drugs, what is of great and still growing importance nowadays.

In the present review the current definitions of lipophilicity and hydrophobicity are discussed. Next, the role of lipophilicity of drugs in living organisms is widely reviewed. The experimental methods of estimation of biological lipophilicity are described in their historical development.

The most widely used method of measuring the lipophilicity of compounds is nowadays the liquid chromatography technique, especially in reversed phase mode (according to the definition of lipophilicity). RP-HPLC is a fast and very precise tool for determination of lipophilicity in a wide range of chemical compounds. In presented paper the influence of the chromatographic systems are described with special attention on novel stationary phases which closely mimic the biological environment (e.g., Immobilized Artificial Membrane phase). Next, the procedures for the determination of chromatographic lipophilicity parameters for a set of derivatives in polycratic and gradient modes are described. The importance of different retention parameters and their usefulness in assessing lipophilicity are widely examined.

Finally, a brief description of calculating methods of lipophilicity estimations is presented.


Wiadomości Chemiczne, 2001, 55, 1047.
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SIMULTANEOUS DETERMINATION OF FAT-SOLUBLE VITAMINS BY MEANS OF HPLC

Sławomir Wieliński Andrzej Olszanowski

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


In this review, selected chemical techniques such as TLC, UV-VIS, GC, HPLC and microbiological procedures (published since 1960) used for simultaneous determination of fat-soluble vitamins in different matrices have been discussed. Particular attention has been given to HPLC methods, not only in terms of chromatographic conditions, but also in comparison with other separation techniques.

HPLC methods have been shown to have clear advantages over existing chemical or microbiological assays in terms of sensitivity, specificity and sample throughput for the analysis of these vitamins. In order to assist the analyst in the selection of a particular procedure, certain chromatographic conditions have been listed for this purpose. However, as currently, no specific HPLC procedures can be recommended, it was decided to develop new methods for these vitamins.

Within the past 30 years, HPLC has become the predominant method for separation and quantification of fat-soluble vitamins. The two major, distinct methods of HPLC separation are referred to as normal-phase chromatography and reverse-phase chromatography. To generalise, reverse-phase HPLC is frequently preferred for analysis of biological samples as the columns are more easily purged of any contaminants and sample separation is usually less sensitive to slight changes in mobile-phase composition. A summary of HPLC systems used for fat-soluble vitamins analysis is provided in Table 1 [60-106] and 2 [107-152] in format: compounds determined, matrix, sample preparation and clean up, column, mobile phase, detection, time of analysis, reference.

Finally, this paper describes a procedure for the simultaneous determination of vitamin A (retinol acetate, palmitate), vitamin D3 (cholecalciferol), vitamin E (alpha-tocopherol acetate) and alphacalcidol in capsules from a single sample extract using reverse phase HPLC and column backflushing techniques [162-165]. The procedure eliminates saponification, lengthy extractions and sample workup. It is specific to the compounds of interest, shows very good internal precision and is free of interference compared to current published methods.


Wiadomości Chemiczne, 2001, 55, 1075.
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TRANSFORMATIONS OF GRAPHITE AND BORON NITRIDE IN SHOCK WAVES

Radosław Trębiński, Andrzej Maranda

Zakład Materiałów Wybuchowych i Fizyki Wybuchu, Wojskowa Akademia Techniczna, ul. Kaliskiego 2, 00-908 Warszawa


Explosives are used in warfare since the 8th century. Nine hundreds years later they were used first in mining. Rapid development of the material science in the last decades of the 20th century caused, that also in this branch of science explosive technology started to be applied. Explosive methods are used among others to: strengthening of surface layers of metals, cladding, alloying, unstressing of intermittent welds and fabrication of superhard materials. Two methods of explosive synthesis of superhard materials have been devised - synthesis in shock waves and synthesis in detonation waves.

In the present work a survey of literature data concerning shock wave synthesis of dense modifications of carbon and boron nitride is presented. The transformations of graphite and graphitic boron nitride under shock loading are characterised.


Wiadomości Chemiczne, 2001, 55, 1103.
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NOTATKI CHAOTYCZNE. XXXVII. O ODKRYCIACH PRZEDWCZESNYCH

Ignacy Z. Siemion

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



Wiadomości Chemiczne, 2001, 55, 1129.
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