Wiadomości Chemiczne, 2007, Vol.61
Instytut Chemii Organicznej Polskiej Akademii Nauk,
ul. Kasprzaka 44/56, 01-224 Warszawa
Influenza (flu) and related viral infections present a constant threat to public health. World-wide efforts have been recently initiated (coordinated by WHO) to prevent global epidemic in view of spreading deadly bird flu virus (H5N1) among people [1, 6]. Attention has been focused on Tamiflu® (1, Figure 1), synthetic, orally active drug manufactured by Hoffmann - La Roche .
On the surface of the flu virus (Figure 3) there are located two proteins important for infecting animal cell: hemagglutinin and neuraminidase (sialidase). Hemagglutinin is responsible for the recognition of specific sialic acids in the cell membrane glycoconjugates; neuraminidase is involved in subsequent hydrolysis of sialic acid residue and is crucial for the virus propagation. Sialic acids are sugar-related keto-acids, as neuraminic acid 2 (Figure 2). Their structure is specific for a given species. Functions of hemagglutinin or neuraminidase have been targeted in systematic search for anti-flu drugs.
The first efficient neuraminidase competitive inhibitor Relanza® (Zanamivir) has been obtained (Scheme 2) as a mimic of hypothetic oxonium ion involved in sialic acid hydrolysis [11, 15]. Many structures related to Zanamivir have been investigated . The most successful line of research has been aimed at synthesis of carbocyclic neuraminic acid derivatives from (-)-quinic or (-)-shikimic acids.
The Gilead-Roche "first generation" analogue with the double bond oriented toward the hydroxy-group 33 proved more active than its counterpart 34 (Figure 9, Scheme 9) [26, 27]. Further modification of the structure 33 was based on X-ray analysis of protein - inhibitor complexes and led to Tamiflu® (Scheme 10).
Prime synthesis of Tamiflu® from (-)-shikimic acid involved several steps (Schemes 5, 6, 10). Since this starting material is rather expensive more economic approaches have been studied. The technological approach to the key epoxide 75 from (-)-quinic acid (Scheme 12) involves bicyclic lactone 70 controlled dehydration to form 73 and regiospecific acetal reduction using borane-dimethylsulfide complex in the presence of a silylating agent . Use of the developed methods and shikimic acid as the starting material allowed for an efficient access to the target epoxide 75 (Scheme 13).
The epoxide 75 has been transformed into the final product in several steps (Scheme 14).
Most advanced synthetic routes transforming 75 into Tamiflu® rely upon the use of tert-butylamine and then diallylamine [11, 33] (Scheme 15).
Current studies on transformation of glucose into shikimic acid by genetically modified strain of Escherichia coli (Scheme 16) are likely to secure supplies of this convenient starting material for Tamiflu® production .
E.J. Corey et al.  have developed enantioselective total synthesis of Tamiflu®. [2+4] cycloaddition reaction of butadiene and trifluoroethylacrylate in the presence of a chiral oxazoborolidine catalyst provided cyclohex-3-enecarboxylic acid derivative (87, Scheme 19). Transformation of 87 into 99 embraced several steps, including the novel haloamidation  (86 into 97). The synthesis route involved 12 steps and afforded Tamiflu® in 25% overall yield.
Catalytic enantioselective reaction of the easily accessible meso-aziridine 101 (Scheme 21) with trimethylsilylazide provided the cornerstone to total synthesis of Tamiflu® by M. Shibasaki et al. . The synthetic route from azide 102 to the target involved several steps (Schemes 23 and 24). Among them the efficient allylic oxidation of 109 and the nickel-catalyzed conjugate addition of trimethylsilylcyanide to α,β-unsaturated ketone 110 that contribute to general synthetic methodology.
In the synthesis developed by Cong i Yao , the starting material - serine-derived aldehyde 117 (Garner's aldehyde, Scheme 25) has been selected from the "chiral pool". The synthesis involves a sequence of diastereoselective reactions (Schemes 25, 26 and 27) and the ring-closure metathesis reaction (130 into 131) using the II generation Grubbs catalyst
Approaches to Tamiflu® illustrate the impressive achievements of organic synthesis. However, at present the high cost of this drug may hamper its broader application.
Keywords synthetic methods, enantioselective synthesis, quinic acid, shikimic acid, antiviral agents, structure-activity relationship
Zakład Chemii Surowców Kosmetycznych, Wydział Farmaceutyczny Uniwersytetu Medycznego w Łodzi,
ul. Muszyńskiego 1, 90-151 Łódź
Cisplatin is an important anticancer drug. Unfortunately it does not bring satisfactory effects in all types of tumor. Other problems are its toxicity and intrinsic or acquired resistance of tumor cells. That is why new drugs based on this molecule are being searched. One of the promising group of chemical compounds are neutral platinum(IV) complexes. They are more inert than platinum(II) complexes. In consequence their reactivity in bloodstream is weaker and more molecules can reach their target.
Many studies were done to establish the relation among the structure, lipophilicity, reduction potential and cytotoxicity of those complexes.
It is believed that platinum(IV) complexes must be reduced to platinum(II) complexes to obtain cytotoxicity. The speed of reduction depends on the nature of axial ligands. The complexes with chloride ligands are reduced the most quickly and complexes with hydroxide ligands are reduced the most slowly. In vitro cytotoxic activity of those complexes was shown to depend on their reduction potential. However suggestions exist that this result can be misleading for their in vivo activity, as platinum(IV) complexes are pro-drugs and might be inactive before reaching cancer cells.
In a study of group of platinum(IV) complexes, derivatives of cisplatin and dichloroethylenediamineplatinum(II), a tendency for an increase of cytotoxic activity when lipophilicity increased was observed. However in a study of tetrakis(carboxylato)(1,2-diaminocyclohexane)platinum(IV) complexes, different cytotoxic activity of complexes possessing similar lipophilicity was observed. Hence lipophilicity of complex is important but it is not the only factor that determines complex activity.
In other studies complexes of general structure cis, trans, cis-[PtNH3(RNH2)Cl2(OCOR')2] were examined. The research showed an increased activity of compounds with longer carbon chains of carboxylate axial ligands. It was also revealed that complexes with alicyclic amine ligands were more cytotoxic than those with aliphatic or aromatic amine ligands.
Hall et al. revealed that platinum(IV) complexes, derivatives of cisplatin and dichloroethylenediamineplatinum(II), are active against DLD-1 colon cancer cell line in hypoxic environment. An examination of trans-dichlorodihydroxo(dimethylamine)(isopropylamine)platinum(IV) revealed its greater cytotoxic activity against A2780, CH1 and 41M human ovarian cancer cell lines, in vitro. Moreover this complex was shown to be active against A2780cisR, CH1cisR and 41McisR human ovarian cell lines which are resistant to cisplatin. Two platinum(IV) complexes: iproplatin (cis, trans, cis-dichlorodihydroxobis(isopropylamine)platinum(IV)) and tetraplatin (tetrachloro(cyclohexane-1,2-diamine)platinum(IV)) have had entered clinical trials. However iproplatin occurred to be less active than cisplatin and tetraplatin turned out to be neurotoxic. Presently two other complexes seem to be very promising: satraplatin (bis(acetato)amminedichlorocyclohexylamineplatinum(IV)) and adamplatin (bis(acetato)(1-adamantylamine)amminedichloroplatinum(IV)). Both have entered clinical trials.
There are some "nonstandard" approaches to investigating platinum complexes. For example platinum(IV) complexes with radioactive iodine isotope or with enzyme inhibitor were examined.
Studies mentioned above present different approaches to searching for anticancer drugs among platinum(IV) complexes. Despite all encountered difficulties during researching platinum(IV) complexes, this group of compounds still seems to be potential source of new anticancer drugs.
Keywords: platinum(IV) complexes, antitumor activity, SAR (structure - activity relationship)
Instytut Chemii Bioorganicznej, Polska Akademia Nauk, ul. Noskowskiego 12/14, 61-704 Poznań
Despite an enormous progress in the development of biophysical methods to establish protein structure and function, there is still a lack of precise ways of detection and mapping the specific fragments of molecules, in terms of their structure and properties. This is due to the fact that only a few amino acids show specific properties - like fluorescence of tryptophan - which enable analysis of the interaction and formation mechanism of protein - nucleic acids complexes. These problems one can easily overcome using proteins containing non-natural amino acid. However, all methods used in in vitro protein synthesis require up till now aminoacyl-tRNA as a substrate. Hence, the acylation of tRNA is a key and limiting step of every method. In the present article, we show all known non-enzymatical methods of tRNA acylation. One of them is based on ribozymes obtained by in vitro evolution (SELEX). These ribozymes that transfer amino acid bound to its 5'-end to 3'-end of tRNA can specifically recognize amino acid or tRNA. Other attempts aimed at chemical synthesis of aminoacyl-nucleotides, which were further ligated to appropriately prepared tRNA. As an amino acid donor, the peptidylnucleic acid (PNA) was used as well. An alternative method is an acylation under high hydrostatic pressure which allows to attach any amino acid to tRNA in a one-step procedure. All mentioned methods can be used in protein translation in vitro. For in vivo synthesis of protein containing non-natural amino acid, orthogonal pairs of tRNA-AARS are used. In orthogonal pairs mutated aminoacyl-tRNA synthetase recognizes specific amino acid and acylates suppressor amber tRNA.
Keywords: protein synthesis, tRNA aminoacylation, non-protein amino acids
Wydział Chemii Uniwersytetu Gdańskiego, ul. J. Sobieskiego 18, 80-952
During the past decades it has been recognized that most of the natural proteins of mammals carry covalently linked saccharide side chains. The carbohydrate portions of the glycoproteins as well as those of glycolipids obviously play key roles in biological recognition processes.
A glycoprotein is a compound containing carbohydrate (or glycan) covalently linked to protein. The carbohydrate may be in a form of monosaccharide, disaccharide(s), oligosaccharide(s), polysaccharide(s), or their derivatives (e.g. sulfo- or phos-pho-substituted). One, a few, or many carbohydrate units may be present.
There are two most common types of glycoproteins: O- and N-glycoproteins. In eukaryotes, the most prevalent type of O-linked glycosylation is the mucin-type glycosylation, where N-acetyl-D-galactosamine (GalNAc) is linked in an α-anomeric configuration to the β-hydroxyl group of either a serine or a threonine residue of the polypeptide. Other types of O-linked glycosylation include glycosaminoglycans, such as heparin and chondrotin sulfate, which are attached to the polypeptide chain through β-linked xylose residues.
An older and more prevalent type of glycosylation, N-linked glycosylation, is found in a wide range of organisms ranging from Archae to mammals and other eukaryotes. N-Glycosylation is a modification performed cotranslationally (during the translation of mRNA to protein) and is available to any secreted or membrane-bound protein containing the triplet amino acid sequence AsnXxxSer/Thr (where Xxx is any amino acid except Pro). An oligosaccharide is transferred to the amide side chain of Asn from a dolichol phosphate glycosyl donor, by the action of mem-brane-bound oligosaccharyl transferase in the endoplasmic reticulum (ER). The fully translated glycoprotein is then subject to glycan trimming and processing which is further elaborated in the ER and Golgi apparatus.
Keywords: N- i O- glycoproteins
Katedra Chemii Fizycznej, Wydział Chemiczny, Politechnika Gdańska,
ul. Gabriela Narutowicza 11/12, 80-952 Gdańsk
The phenomena behind proton hydration in aqueous solution are still far from being fully understood and have attracted scientific attention for many decades now. This article reviews the current state of studies of this seemingly simple system, focusing particularly on the most popular techniques applied: computational chemistry, vibrational spectroscopy and diffraction methods.
The picture of proton transfer via the Grotthuss mechanism (Fig. 1) , has lately been critically examined basing on up-to-date experimental and computational data , but it is still found relevant in biological systems, e.g. in proton-transferring proteins .
The lengthy and heated debate on the identity of hydrated proton in an aqueous solution [6, 11, 12] has focused for many years on two isomeric structures (Fig. 2), the so-called "Eigen cation"  and "Zundel cation" . The findings of the last decade have proved that these two forms coexist in a dynamic equilibrium [5, 13-25], and that the answer to this problem may as well be in the middle [26-28]. The most recent reports from the last few years are reviewed here in considerable detail.
Keywords: proton hydration, aqueous solutions, hydrogen bonding, vibrational spectroscopy, diffraction methods, quantum-mechanical calculations
1Wydział Chemii Uniwersytetu Adama Mickiewicza, Poznań
2Wydział Chemii Uniwersytetu Wrocławskiego, Wrocław.
A short biography and scientific achievements of Professor Georg Zundel, outstanding German physico-chemist, are presented. His main successes are related to strong hydrogen bonds, spectroscopy of strong specific interactions and particularly the role of a double minimum potential in creation of continua. Majority of papers were devoted to biological systems and simpler compounds modelling these systems. In the world literature the simplest hydrated proton H5O2+ is commonly named as the Zundel cation.
1 Wydział Chemii, Uniwersytet im. Adama Mickiewicza, ul. Grunwaldzka 6, 60-780 Poznań
2 Wydział Fizyki, Uniwersytet im. Adama Mickiewicza, ul. Umultowska 85, 61-614 Poznań
3 Centrum Badawcze Ultraszybkiej Spektroskopii Laserowej, Uniwersytet im. Adama Mickiewicza, ul. Umultowska 85, 61-614 Poznań,
4 Instytut Chemii Fizycznej, PAN, ul. Kasprzaka 44/52, 01-224 Warszawa
The paper presents results of spectral and photophysical studies obtained for molecules representing three different classes of compounds:
• Schiff bases with strong intramolecular hydrogen bond, occurring in a few phototautomers,
• Aminophtalimides with LE and ICT type electronic excited states forming exciplexes through hydrogen bonds with the solvent molecules,
• Thioketones with a thiocarbonyl group becoming exceptionally reactive in the S2 state, quenched by molecules of solvent of different properties.
It should be emphasized that for all compounds, irrespective of the complex mechanisms of their deactivation characterised by different dynamics, the dominant final process is the reproduction of the chemically unchanged substrate in the ground state. The necessary condition of the correct interpretation of the complex properties of the compounds studied in electronic excited states is the proper choice of solvents of specific properties. Through this proper choice of solvents it becomes possible to study the role of nonspecific and specific (hydrogen bonds) interactions with the solvent and to observe the intramolecular and intermolecular processes of deactivation. The results presented could be obtained thanks to the use of the steady-state and time-resolved laser methods of absorption and emission spectroscopy with a pico- and femtosecond resolution.
The results obtained can be helpful in the study of compounds of similar properties and more complex systems including biological systems.
Keywords: Schiff bases, aminophtalimides, thioketones, excited states, intramolecular proton transfer, hydrogen bonds, exciplex, picosecond and femtosecond laser spectroscopy.
Instytut Chemii Ogólnej i Ekologicznej, Politechnika Łódzka ul. Żeromskiego 116, 90-924 Łódź
Gramicidin D (gD) is a naturally occurring mixture of six linear pentadecapeptides produced by Bacillus brevis species in soil, which exhibit significant antibacterial activity against all Gram+ bacteria. The peptides are modified at both ends and the six forms differ at 1st (Val or Ile) and 11th (Trp, Phe or Tyr) positions. The most populated gramicidin A (VgA) has a sequence CH(O)-Val1-Gly-Ala-D-Leu-Ala-D-Val-Val-D-Val-Trp-D-Leu-Trp11-D-Leu-Trp-D-Leu-Trp-NHCH2CH2OH.
Gramicidin was isolated in 1939 and its sequence was determined five years later. First models of its secondary structure based on helical conformation were proposed in 1971-1974 explaining channel-like properties of the peptide.
Despite over 60 years of studies on gramicidin, there are still numerous unans-wered questions concerning its structure and functioning. Even fundamental issues of dimers type and handedness of helices in the gramicidin channel formed by the peptide in the bacterial cell membranes are not univocally accepted.
After refining several crystal structures of gramicidin D complexes with alkali metal salts, we have at hands not only more facts concerning double-stranded antiparallel gramicidin dimers, but also new puzzled observations due to very high reso-lution data collected. These, among others, include visible asymmetry of cations' sites and occupations in the gramicidin channels, as well as specific arrangement of heterodimers in the crystals.
The paper describes these interesting features of the complexed gramicidin structure and proposes some new explanations.
Keywords: complexes of gramicidin, crystal structure of gramicidin, heterogeneity of gramicidin dimers, distribution of cations in the gramicidin dimers.
Instytut Chemii, Wydział Nowych Technologii i Chemii, Wojskowa Akademia Techniczna, ul. S. Kaliskiego 2, 00-908 Warszawa
Nanostructured energetic materials (nanoems) are compositions of a fuel and an oxidizer that are homogenous at a nanometric scale. They are prepared in three basic forms: (i) as thin multilayered foils consisting of alternating layers of oxidizer and fuel, (ii) mixtures of fuel and oxidizer nanoparticles, and (iii) mixtures obtai-ned via sol-gel synthesis. Thin foils are nanoscaled only in one dimension. in such composites, there are large, regular planar interfaces between fuel and oxidizer layers which thickness is below 100 nm. The composites are characterized by a very close physical contact of reactants and a lack of impurities between them as they are usually obtained by vacuum deposition of the components. The second kind of nanoems are mixtures prepared by powder mixing of nanometer sized particles of oxidizer and fuel. components are previously produced via chemical or physical processing and then mixed in an appropriate solvent. being consisted of the same components as conventional thermites (metal powders - usually al, and metal oxides - usually Fe2O3), this nanocomposites are known as "superthermites". In contrast to the conventional thermites, supertermites are very sensitive to ignition and they may burn at a velocity of 1 km/s or even more. Synthesis of nanoems using sol-gel chemistry is a solution phase synthetic route. Its benefits include the convenience of low-temperature preparation using general and inexpensive laboratory equipment. The nanoparticles of both oxidizer and fuel precipitate from a colloidal solution (sol). This means that nanocomposites are formed by simultaneous condensation and/or crystallization of dissolved molecular precursors, i.e. by growth of particles and not by their size reduction. The obtained gels (organic and/or inorganic substances) are dried either by controlled evaporation of solvent, by freeze-drying or by supercritical extraction. The size of the particles (homogeneity of the composition) can be varied by changing synthesis and drying conditions.
keywords: energetic materials, nanostructures, sol-gel synthesis.
Wydział Chemii Uniwersytetu Gdańskiego,
ul. J. Sobieskiego 18, 80-952 Gdańsk
Antibiotics, such as penicillin or streptomycin, are substances produced by or derived from certain fungi or bacteria, that can destroy or inhibit the growth of other microorganisms. Antibiotics are widely used in the prevention and treatment of infectious diseases.
Glycopeptide antibiotics are a class of antibiotic drugs. They consist of a glycosylated cyclic or polycyclic nonribosomal peptide. Important glycopeptide antibiotics include vancomycin, teicoplanin, ramoplanin, and decaplanin. This class of drugs inhibits the synthesis of cell walls in susceptible microbes by inhibiting peptidoglycan synthesis. Glycopeptides exhibit a narrow spectrum of activity as principally effective against gram positive cocci. They are the last line of effective defense against MRSA and multiresistant enterococci for patients who are critically ill.
At the beginning of the 90' there started a large scale research program for finding glycopeptide antibiotics with optimized properties. These studes resulted in the discovery of the hemi-synthetic compounds (1996 oritavancin) which have lower toxicity than vancomycin.
Keywords: vancomycin, glycopeptide, glycopeptide resistance.
Instytut Oceanografii, Uniwersytet Gdański, Al. Marszałka Piłsudskiego 46, 81-378 Gdynia
Cyanobacteria are photosynthetic prokaryotes that produce a wide range of secondary metabolites. Part of them is toxic or shows bioactivity in other organisms, including mammals [1-2]. The main classes of cyanobacterial toxins comprise of hepatotoxins, neurotoxins, cytotoxins, dermatotoxins and lipopolysaccharides . Hepatotoxins, microcystins and nodularins are the most common cyanotoxins. Microcystins, the cyclic heptapeptides  are produced by freshwater cyanobacteria of the genera Microcystis, Anabaena, Planktothrix (Oscillatoria), Nostoc, Hapalosiphon and Anabaenopsis. Nodularin (NOD-R) the cyclic pentapeptide hepatotoxin  is produced by brackish water cyanobacterium Nodularia spumigena. Microcystins and nodularins are extremely toxic due to their action on type 1 and 2A protein phosphatase enzymes that play a key role in the control of cellular meta-bolism . The main groups of neurotoxins produced by cyanobacteria include anatoxin-a, anatoxin-a(s), saxitoxins  and the recently identified β-N-methylamino--L-alanine (BMAA) . The latter has been reported to biomagnify within the Guam ecosystem and was suggested to be a possible cause of the amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) .
In the Baltic Sea N. spumigena is the main toxic and bloom-forming cyanobacterial species . Nodularin concentration can temporarily reach over 20 mg dm-3 . The toxin accumulates in different elements of the Baltic ecosystem, including sediments, mussels and fish [8-9]. Apart from NOD-R, minor amounts of other NOD analogues have been characterized in N. spumigena cells [4, 10]: geometrical isomers, linear forms, three demethylated analogues and three analogues with additional methyl group. Nodularin is characterized by high stability. The loss of the toxin in water is mainly due to degradation by the naturally occurring bacterial community . However, the UV radiation as well as sorption on sediments and sus-pended particles has also some impact on nodularin concentration. In organisms microcystins are detoxified by conjugation with activated glutathione, however, the pathway of nodularin biotransformation has not been revealed yet.
Keywords: cyanobacteria, hepatotoxins, neurotoxins, nodularin, Nodularia spumigena.
Zakład Ziem Rzadkich, Wydział Chemii, Uniwersytet im. A. Mickiewicza, ul. Grunwaldzka 6, 60-780 Poznań
The aim of this review is to evaluate the electrochemiluminescence (ECL), both, as a method of light emission in certain types of lanthanide complexes by generating species capable of forming excited states, and for its potential use in analytical applications. The electrogenerated ECL in aqueous electrolyte solutions containing organic compounds having structural fragments such as carbonyl groups and conjugated double bonds and an oxide covered aluminum electrode doped with Ln(III) is reported. This specific electrogenerated luminescence can be achieved by producing highly oxidizing and reducing species as: hydrated electrons, hydroxyl and sulfate radicals. Such strong reactants efficiently excite the complexed lanthanide(III) ions [mainly Tb(III) and Dy(III)] by ligand to metal energy transfer, LMET.
The experimental setup for ECL measurements (constructed in the Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University) is introduced. The ECL generated with aluminium electrodes having chelated lanthanide(III) complexes-doped in their thin oxide coatings is studied following cathodic pulse polarization. The ECL mechanisms induced by hot-electrons leading to the production of light at or near the electrode surface by generating species capable of forming excited states of organic ligands are described.
Keywords: electrochemiluminescence, lanthanide complexes, energy transfer.
Wiadomości Chemiczne, 2007, 61, 279.
Zakład Dydaktyki Chemii, Wydział Chemii UAM, ul. Grunwaldzka 6, 60-780 Poznań
In order to teach effectively and efficiently, one has to combine various elements of depiction and visualization, as well as to create emotional, imaginative and sensational linkages in the learner's mind. Visualization allows to get through to one's real, inner, and subjective emotions, sensations and images. It is sometimes said that our eyes are an interface between our brain and the outside world. A good example of putting this assumption into practice can be found in the educational packages backing up chemistry curricula at different educational levels. The multimedia software designed or code signed by the author of the article comprises either succinct printed textbooks with integral CDs, or multimedia textbooks available both on CDs and on the Internet.
Each of the CD multimedia lessons contains animations and simulations of chemical processes and phenomena, dynamic and three-dimensional element and compound models, tests and problem solving tasks, as well as film sequences illus-trating chemical experiments. Not only do those films allow the user to watch respective fragments of a given experiment in close-up so as to analyze interrelationships between them, but they can also be played repeatedly, thus making the user memorize the sequence of laboratory activities or the course of industrial processes. Such presentations of experiments can help teachers and students who are, for some reasons, unable to carry them out on their own. They are also an inspiration for those willing to carry out new experiments and, above all, an aid to those looking for didactic means to explain complex questions. What is important is that all experiments presented on the CDs are only those that can be always carried out safely, successfully and economically. Their visualizations create images of the course of chemical experiments in the learner's mind, which, though no substitute for their actual replication, can still be a valuable source of knowledge.
The article additionally presents the interactive board as means of creating and saving interactive educational images, a tool of interactive evaluation of knowledge and skills, a field for playing educational games, a device helping the teacher organize his work, a medium of remote teaching, and a his inspiration for carrying out and interpreting experiments.
Keywords: chemistry, didactics of chemistry, information technology, multimedia textbooks.
Zakład Chemii Koordynacyjnej, Wydział Chemii Uniwersytetu im. A. Mickiewicza,
ul. Grunwaldzka 6, 60-780 Poznań
Nucleotides, being multifunctional ligands with donor nitrogen and oxygen atoms, take part in the majority of selective and specific processes occurring in nature [1-15]. It has been established that nucleotides react with the polyamines (biogenic amines) present in the living organisms and take part in genetic information transfer [16-24]. Nucleotides are composed of a purine or pyrimidine base, sugar residua and phosphate groups (Fig. 1) [25-27]. Each of the three components have potential centres of interaction with metal ions [28-29]. Because of the wide diversity of coordination possibilities there are often controversies as to the mode of coordination even in simple complexes with metal ions. Some authors claim that only nitrogen atoms of the nucleotide are effectively engaged in the metallation [30-43], while others maintain that it requires a combined engagement of nitrogen atoms and phosphate group [44-71]. There are also researchers who point to the involvement of only phosphate group of the nucleotide in the metallation [72-77].
The reaction of nucleotides with tetramines results in the formation of molecular complexes (Fig. 3) [78-88]. In the literature to date, there is no agreement as to the character of interactions and effectiveness of nucleotide donor groups in the formation of adducts with polyamines [80-82, 85-87, 89, 90]. According to some authors, the interaction between a nucleotide and polyamines in the metal-free systems has a noncovalent ion-ion or ion-dipole nature and the stability of molecular complexes is determined by the number of active centres in the reagents and the structural factor [80-84, 87]. According to other authors, it is a typical electrostatic interaction and the adduct stability is determined by the charge of the reagents [85, 89]. In the adducts formed by nucleotides with polyamines, the main interaction centres of a nucleotide are endocyclic nitrogen atoms and a phosphate group (the latter undergoes deprotonation already at a low pH), while in the case of tetramine the interaction centres are the NHx+ groups [77, 80-87, 89-91].
In the ternary systems of metal/nucleotide/tetramine, the following heteroligand molecular complexes are formed: ML······HxL' (x = 4, HxL'-fully protonated polyamine) (Fig. 4) [80-82, 91, 94, 96], mixed protonated complexes MLHxL' (x = 1, 2, 3) (Fig. 5) [81, 82, 92, 96] and MLL' type complexes (Fig. 6) [81, 82, 91]. A significant influence of polyamines on the character of interactions of nucleotides with metal ions has been noted [80-82, 90-96]. In molecular complexes, the fully protonated polyamine is located in the outer coordination sphere. In the MLHxL' type complexes, the deprotonated nitrogen atoms of tetramine are involved in the coordination, while its protonated centres -NHx+ take part in noncovalent interactions that additionally stabilise the complex [81, 82, 92, 96, 97]. In the MLL' type complexes, oxygen atoms of nucleotide phosphate group and deprotonated nitrogen atoms of tetramine are in the inner coordination sphere, while nucleotide donor nitrogen atoms do not take part in the metallation [81, 82, 91].
Keywords: molecular complexes, coordination compounds, nucleotide, tetramine, Cu(II), Ni(II), Co(II)
Mariusz Łukaszewski a, Andrzej Czerwiński a,b
a Wydział Chemii Uniwersytetu Warszawskiego, ul. Pasteura 1, 02-093 Warszawa
b Instytut Chemii Przemysłowej im. prof. I. Mościckiego w Warszawie, ul. Rydygiera 8, 01-793 Warszawa
In this paper are summarized the results concerning studies on fundamental electrochemical properties of binary and ternary noble metal alloys in acidic solution. The systems were characterized electrochemically using cyclic voltammetry technique (CV). A CV curve can be treated as a basic mean of in situ surface analysis of electrodes of this type. The voltammogram recorded under given experimental conditions is characteristic of the individual noble metal or alloy and it is an electrochemical 'fingerprint' of the investigated sample. Qualitative and quanti-tative conclusions can be drawn about the surface state of noble metal alloys on the basis of the course of CV curves by the use of the distinctive features associated with each component. Such an analysis is possible due to the fact that the voltammograms for pure metals differ markedly from each other in respect of the region of surface oxide formation and its reduction as well as the appearance of the region where hydrogen electrosorption takes place. In particular, the potential of the oxygen desorption peak is a linear function of the alloy surface composition. The influence of the procedure of prolonged potential cycling on electrochemical behavior of the alloys is presented. During the electrochemical treatment the alloy surface becomes enriched with components that are more resistant to electrochemical dissolution, occurring at sufficiently high potentials. The course of the voltammogram undergoes dramatic changes concerning the signals originating from hydrogen and oxygen electrosorption. As a result of the procedure of potential cycling both alloy surface and bulk can become heterogeneous. Selective removal of alloy components during the electrochemical treatment allows for in situ preparation of alloy electrodes possessing a variety of electrocatalytic properties.
Keywords: noble metals and their alloys, hydrogen and oxygen electrosorption, electrochemical treatment, cyclic voltammetry.
Instytut Chemii, Uniwersytet w Białymstoku,
ul. Hurtowa 1, 15-399 Białystok
The increasing concentrations of platinum and palladium in the environment have been observed in the last quarter of the last century. The review summarizes current knowledge concerning the emission of platinum and palladium into biosphere, environmental mobility of these metals, their speciation and bioavailability for living organisms.
The main sources of emission of these metals are chemical, petroleum and electronic industries, car catalytic converters, hospitals and jewellery [8, 9, 31]. Platinum, palladium and rhodium are released from automobile catalysts during vehicle operation in the form of nanometer size particles, mainly in metallic form . These fine particles [21, 23] are mostly deposited close to the communication routes (in a road dust and soil) [31, 33, 34], but the last evidence showed that due to atmospheric dispersion they could be also transferred for longer distances, even to glaciers and snows of central Greenland [29, 35, 51]. The storm water transports particles containing Pt and Pd into road drainage basins, sludge and aquatic environment (urban lakes and rivers and their sediments) [43, 44, 49]. The increased concentrations of precious metals were found in different environmental samples such as atmospheric aerosols and particulate matter, road and tunnel dust, soil, lake and river sediments, snow and vegetation growing in the roadside environment. The total deposition of these elements in the northern hemisphere was assessed as 20-50 ton/year of Pd and 9-20 ton/year of Pt .
Platinum and palladium are chemically inert, but under atmospheric conditions (rainwater of low pH, high content of chlorides) and operation of natural complexing agents can be partially oxidized and transformed in soil and sediments into soluble species [47-53, 66]. In such form they became available for plants growing on contaminated soil or can be taken up by aquatic animals such as isopods, mussels, fish, and parasites [69-75, 87-90, 93, 97]. The experimental data shows that palladium is the most mobile and bioavailable element among other platinum group metals (Pd > Rh ? Pt). The bioaccumulation factors of palladium for plants and aqueous animals are similar to that calculated for copper and a magnitude higher than occurring for lead [73, 89] [Tables 1 and 2]. The plant and animal cells in the presence of high concentration of palladium induce production of sulfur-rich detoxification compounds, such as phytochelatines for plants [72, 81] and metallothioneins for animals [48, 98]. The internal organs of birds living in natural habitat also contain elevated concentrations of noble metals [100, 101]. The higher concentration of palladium (and rhodium) than platinum were found in urine of unexposed individuals [105, 106, Table 3], what suggests a different environmental mobility and metabolism of Pd and Rh. The Pd level in human urine, but not Pt, was correlated with traffic intensity .
Recent investigations confirmed that platinum and palladium of anthropogenic origin are accumulated in environment and they have high biological availability for plants, animals and humans.
Keywords: platinum, palladium, emission, environment, bioavailability, bioaccumulation, plants, animals, humans.
1 Centrum Badań Molekularnych i Makromolekularnych Polskiej Akademii Nauk, Zakład Chemii Bioorganicznej,
ul. Sienkiewicza 112, 90-362 Łódź
2 Wydział Matematyczno-Przyrodniczy, Instytut Chemii i Ochrony Środowiska, Akademia im. Jana Długosza, Al. Armii Krajowej 13/15, 42-200 Częstochowa
Several nucleoside analogues have found successful application as antiviral and anticancer agents. Their mode of action differs, but in the most general terms they have been developed as inhibitors or competitors of natural 2'-deoxynucleosides in the process of their conversion to the corresponding nucleoside-5'-triphosphates. As such, they can be incorporated into a growing viral DNA strand by a DNA polymerase resulting in chain termination. In cancer therapy, modified nucleosides, after being phosphorylated to the corresponding monophosphates, block DNA biosynthesis by deactivating nucleoside syntheses. Hence biological activity of nucleoside analogues in most cases depends on the intracellular phosphorylation by viral and/or cellular kinases to their respective mono-, di-, and triphosphate derivatives. Among the three successive activating phosphorylation steps the first one has fundamental importance as the rate-limiting step. Several different enzymes can perform this initial phosphorylation, depending on the nature of the aglycone. Also, the presence and activity of the intracellular enzymes necessary for the activation of nucleoside analogues are highly dependent on the host species, the cell type, and the stage in the cell cycle. Moreover, in many cases, nucleoside analogues are poor substrates for the cellular kinases needed for their activation. For all these reasons, intracellular nucleoside monophosphate (NMP) delivery has been considered for overcoming the first phosphorylation step.
Unfortunately, NMPs themselves cannot be used as potential chemotherapeutic agents. Owing to their high polarity, these compounds are not able to penetrate cellular membrane or the blood-brain barrier easily. Therefore, in order to reduce the phosphate negative charge and enable the modified nucleotide to enter the cell, many nucleotides modified on the phos-phate moiety by so-called masking group have been synthesized.
A suitable nucleotide prodrug (so-called pronucleotide) has to fulfill two requirements: i) it has to be lipophilic enough for passive diffusion of the membrane and the blood-brain barrier; ii) it should be able to deliver the nucleoside by chemical or enzymatic hydrolysis leaving a non-toxic masking group.
Many strategies using various protecting groups for the phosphate moiety have been deve-loped to achieve this goal. The majority of strategies for unmasking pronucleotides that have been examined to date have involved substrate-nonspecific enzymes to remove one or more groups that are attached to the 5'MP moiety. Carboxylesterases (CEs) have attracted considerable attention, since they include bis(pivaloyloxymethyl) [(bis(POM)] and S-acyl-2-thioethyl (SATE) moieties which are initially unmasked by CE-mediated cleavage. A combination of aryl ester and amino acid phosphoramidate groups as a particular class of enzyme-labile protecting groups was developed for the delivery of antiviral nucleoside prodrugs. An endogenous phosphoramidase was responsible and necessary for the biological activity of those compounds in living cells.
On the other side almost all approaches based on chemical hydrolysis reported so far were unable to deliver the nucleotide selectively exept the cycloSal approach.
This review will predominantly concentrate on the different approaches to the design of nucleotide prodrugs.
Keywords: prodrug, pronucleotide, nucleoside analogues, antiviral activity, anticancer acti-vity, masking groups.
1 Katedra i Zakład Chemii Organicznej,
2 Katedra i Zakład Żywności i Żywienia,
Wydział Farmaceutyczny z Oddziałem Medycyny Laboratoryjnej, Śląska Akademia Medyczna, ul. Jagiellońska 4, 41-200 Sosnowiec
Naturally occurring enediyne anticancer antibiotics derived from bacterial sources are reviewed. The enediynes represent promising chemotherapeutic agents that exhibit unprecedented molecular architecture, fascinating modes of action and extremely potent anticancer activity, more potent than other anticancer drugs. The enediynes are structurally characterized by an unsaturated core with two acetylenic groups conjugated with a double bond. All these molecules contain three impor-tant functional domains:
- an enediyne ring (nine-membered or ten-membered) as a highly reactive core that generates the reactive diradicals, thus providing the fragments that damage DNA,
- a triggering device which after suitable activation under physiological conditions initiates the cascade of reactions that leads to the generation of diradicals,
- a delivery system that is responsible for targeting DNA.
The mode of action of the enediyne antibiotics is the ability to produce single--stranded or double-stranded DNA lesions by a mechanism which involves the inter-actions with duplex DNA along specific sequences within the minor groove. This is followed by the formation of a highly reactive benzenoid diradical via Bergman or Myers-Saito cyloaromatization and abstraction of hydrogen atoms from the deoxyribose of DNA leading to site-specific DNA breaks, which induces cell apoptosis.
The diradical (p-benzyne) intermediates in simple prototype enediynes were postulated by Bergman in 1972 and provided the basis for the mechanism of action of the naturally occurring enediynes.
Over 20 natural enediynes antibiotics are known now. They are divided into two distinct groups; those containing a nine membered enediynes chromophore non-covalently associated with a stabilizing apoprotein (neocarzinostatin 1, kedarcidin 2, lidamycin 3, maduropeptin 4, N1999A2 5) and those containing ten membered enediyne ring (calicheamicins 6, dynemicins 7, esperamicin 8, namenamicin 9, shishijimicins 10). However, the lack of selectivity for cancer cells and toxicity of natural enediynes have complicated their use in cancer chemotherapy. Several mono-clonal antibody-enediynes and polymer-enediynes conjugates have been prepared and evaluated for clinical significance as anticancer drugs. Much effort has been devoted to the design and synthesis of new, simplified, fully synthetic analogues characterized by similar mode of action.
Keywords: enediyne antibiotics, prodrugs, cycloaromatization, diradicals, DNA, cytotoxicity
Instytut Chemii i Technologii Organicznej, Politechnika Krakowska,
ul. Warszawska 24, 31-155 Kraków
In this work the reported in literature (4+2)π-electron cycloadditions, where a two-step mechanism was postulated and more or less thoroughly documented, has been subjected to a critical analysis. The research has been focused on [2+3] and [2+4] cycloadditions. To-date not many detailed studies, which would lead to unambiguous conclusions have been performed in this area. The two-step reaction
mechanism of thiocarbonylylides with 1,2-dicyanoethene derivatives, π-deficient cyclic ylides with 1-(dimethylamino)-propyne and 1,1-dimethoxy-1,3-butadiene with π-deficient ethene derivatives can be considered as the most documented ones. On the other hand, the reports where a non-concerted mechanism of [2+3] cycloaddition of nitrile oxides with dideuteroethenes and [2+4] cycloaddition of 2-methylfurane with 1,2-dicarboxyethene was postulated are less reliable.
Keywords: cycloaddition, Diels-Alder reaction, mechanism, biradical, zwitterion.
Wydział Inżynierii Chemicznej i Procesowej, Politechnika Warszawska,
ul. Waryńskiego 1, 00-645 Warszawa
Instytut Chemii i Techniki Jądrowej, ul. Dorodna 16, 03-195 Warszawa
Radiation chemistry is a part of the physical chemistry similary like photo-chemistry, plasma-chemistry, ultrasonic-chemistry etc. Ionizing radiation produces abundant secondary electrons (Fig. 1). Following these primary events, the ions, secondary electrons and excited molecules undergo further transformations, exchanging charges and energy and reacting with surrounding molecules, thereby producing free radicals and other reactive species which finally evolve into new stable products. Three main sources of radiation are applied for radiation processing . These are electron accelerators , gamma sources  and X-ray unit based on e-/X conversion process .
Radiation processing was used early on for polymer modification [15, 16]. The intermediates formed during material irradiation can follow several reaction paths that result in disproportion, hydrogen abstraction, arrangements and/or the formation of new bonds. Nowadays, the modification of polymers  covers radiation cross-linking (Fig. 2), radiation-induced polymerization (graft polymerization and curing) (Fig. 4) and the degradation of polymers (Fig. 3) . Some polymers predominantly undergo crosslinking other degradation (Tab. 1). However new techniques allow crosslinking of polymers which were considered to be degradable only, like PTFE  and cellulose derivatives . Regarding natural polymers the biggest application concerns rubber pre-crosslinking in tire industry . The processing of natural polymers is also being developed to elaborate new biodegradable materials . The radiation crosslinked wires and cables show excellent heat resistance (long-term thermal stability and short-term thermal stability) as well as abrasion resistance [26, 33-35]. Other big application is crosslinking of XLPE type pipes which are widely used for hot water and floor heating . Polybutelene terephtalate (PBT), which is a plastic for electronic industry, can be crosslinked by radiation and lead free soldering materials can be applied in such a case . This method of crosslinking is also applied to manufacture thermoshrinkable tubes and types possessing "memory effect" [36, 37]. Through radiation, grafting metal adsorbents and ion exchange membranes can be developed (Fig. 5) .
Radiation is early applied tool in the area of nanomaterials engineering; arrangement of atoms and ions has been performed using ion or electron beams for many years . New trends concern surface curing and development of ion track membranes and controlled release drug-delivery systems . Finally, radiation processing concerns gem stones colorization, development of high temperature resistant fibers (SiC) and semiconductor modification .
Over the past few years, radiation processing technologies aimed at ensuring the safety of gaseous and liquid effluents discharged to the environment have been developed. It has been demonstrated that radiation processing based technologies for flue gas treatment (SOX and NOX removal), wastewater purification, and sludge hygienization can be effectively deployed to mitigate environmental degradation [51, 52]. Electron beam technology is among the most promising advanced technologies of new generation. This is a dry-scrubbing process of simultaneous SO2 and NOx removal, where no waste except the fertilizer by-product are generated [53, 54].The other possibility is application of the process for VOC removal. Tests at the pilot plant constructed at a coal-fired power station were performed with the purpose of estimating the influence of electron beam on VOCs present in flue gas, during SO2 and NOx removal [59, 60]. The removal efficiencies have been ranged from 40% up to 98%. The chlorocarbons including dioxins may be removed with high efficiency as well [57, 58]. During the radiolysis of water reactive radicals of strong oxidizing or reducing properties are formed that can transform the pollutants in the liquids wastes (Fig. 10, 11) [61, 62]. A large number of substances such as hard surfactants, lignin, pesticides cannot be degraded by conventional biochemical methods and thus escape from decomposition in biological treatment. Research and industrial (Fig. 13) treatments testify significant improvement of pollutant biodegradability after radiation-oxidation in aerated wastewater .
Keywords: radiation chemistry, electron accelerators, gamma sources, polymers, nanomaterials, environment protection, flue gas and wastewater purification.
Wydział Chemii, Zakład Chemii Polipeptydów, Uniwersytet Gdański, ul. J. Sobieskiego 18/19, 80-952 Gdańsk
Copper is an essential metal in living organisms . They all require copper as a catalytic cofactor for biological processes such as respiration , iron transport [2-5], oxidative stress protection  and pigmentation .
Nevertheless, exposure to the excess of copper can damage cells and organs. Copper ions and complexes can induce formation of reactive oxygen species, that can damage biomolecules including unsaturated lipids and DNA. In the past few years exciting advances have been made toward understanding how copper is transported within cells. Dysfunction of copper metabolism can lead to its excess or defi-ciency. Two examples of illness related to alterations in copper metabolism are Menkes and Wilson diseases .
The understanding of copper homeostasis has become important in clinical medicine as the metal could be involved in the pathogenesis of some neurological disorders such as Alzheimer, Parkinson or prion diseases [3, 5].
Keywords: copper, hCTR, cellular prion protein, ATP7A, ATP7B, PINA, metallothionein, ceruloplasmin.
1 Laboratorium Wirusologii Molekularnej i Chemii Biologicznej,
Centrum Biologii Medycznej PAN,
ul. Lodowa 106, 93-232 Łódź
2 Katedra Endokrynologii i Chorób Metabolicznych, Zakład Biologii Strukturalnej, Uniwersytet Medyczny, ul. Żeligowskiego 7/9, 90-752 Łódź
Carboranes are boron cage systems in which one or more carbon atoms belong as an integral part to an elektron-delocalized borane framework. They are characterized by high boron content, remarkable thermal and chemical stability, spherical geometry and high hydrophobicity . Electropositivity of boron enables BH groups in carboranes to form unconventional hydrogen bonds defined also as proton - hydride bond. Another type of interaction was found for CH group of carborane - participating in hydrogen-bonded complexes, although these complexes are approximately 21 kJ/mol less stable than complexes formed by BH groups [2-8]. Proton - hydride bonds are formed mainly due to electrostatic interactions between boron--bound hydrogen atom bearing partial negative charge and hydrogen atom of a biomolecule bearing partial positive charge. It was found that carboranes forms proton - hydride bonds with biomolecules preferably with BH groups of the cage opposite to the carbon atom .
Carboranes have been used as hydrophobic pharmacophores in design of analogues of biologically active compounds such as estradiol, retinoic acids, protein kinase C modulators and TNF-? activity modulators [9-14]. Some of these carbo-rane containing biomolecules interact effectively with the corresponding receptor enzymes exhibiting equal or even higher biological activity than their endogenous counterparts and are characterized by remarkable resistance to catabolism.
Keywords: carboranes, hydrophobic pharmacophore, receptors, drugs.
Instytut Oceanologii Polskiej Akademii Nauk,
Pracownia Chemicznych Zanieczyszczeń Morza,
ul. Powstańców Warszawy 55, 81-712 Sopot
Organic compounds occur in a sea usually at lower concentrations than inorganic compounds. Nevertheless, their role in this environment is very important and still not elucidated, due to variety of compounds and their forms, and analytical pro-blems. However, while taking into account all the difficulties and limits, the information which we get from such analyses, is worth the time and often a high price.
The information about the state of the marine environment, possible to obtain from the organic compound distribution, will be presented on an example of the three groups of organic compounds. These are: polychlorinated biphenyls (PCBs), polynuclear aromatic hydrocarbons (PAHs), and plant pigments, especially chlorophylls and their derivatives. Polychlorinated biphenyls are anthropogenic com- pounds, included to the most harmful pollutants for the marine environment, and as such, occurring at the lists of dangerous substances of all the conventions concerning the marine environment, especially HELCOM, OSPAR, Barcelona Convention and also Stockholm Convention concerning the persistent organic pollutants (POPs). The aromatic hydrocarbons can be both of anthropogenic and natural origin, the latter being produced in the sea, e.g. by marine organisms or of the natural slicks of petroleum from the sources under sea bottom as well as originating from land, e.g. as a result of wood fires or floods. The third group of the presented com-pounds - plant pigments - is of the natural origin but their occurrence in a sea is often also anthropogenic.
The properties and concentration levels of these compounds in the marine environment will be described, indicating which phenomena are responsible for their distribution. Besides, the analytical methods used for their determination will be presented along with difficulties in their analysis and interpretation of results.
Keywords: organic compounds, marine environment, markers.
ul. J. Bytnara 23 m. 19, 02-645 Warszawa,
(Em. profesor Uniwersytetu Warszawskiego)
At the turn of XVIII c. at the Polish territory chemistry was taught at the three universities: in Krakow (lectures in polish), in Wilno (lectures in latin and from 1797 in polish) and in Lwów occupied by Austrian Empire (lectures in german). The lectures in polish had continued in Krakow during the whole XIX c. In Wilno the university was closed by Russian authorities in 1832 after the Polish anti-Russian uprising. The same year the Russian authorities had closed the polish Univer-sity in Warszawa opened in 1816. The other polish University that was active in Warszawa in 1862-1869 was replaced by the Imperial (Russian) Warsaw University that became polish in 1915. At the Lwów German University and the Lwów German Technical Academy (from 1872 Technical University) the lectures of chemistry were given in polish from 1872. After regaining of independence by Poland in 1918 the Wilno University was renewed and a new University in Poznań was organised. The activity of the chemistry chairs at these universities are discussed in the article.
Keywords: teaching, chemistry, Poland, years 1783-1939.
Wydział Inżynierii i Technologii Chemicznej, Politechnika Krakowska, ul. Warszawska 24, 31-155 Kraków
The charge, concentration and electron balances are closely related to other, more elementary rules of conservation of a matter in a closed system, separated from the environment by diathermal walls. The conservation rules can be formulated for the elements, electrons and protons.
Among others, the generalised electron balance (GEB) concept presented and applied in some author's papers [1-7, 14-16] is derived from the elementary rules of conservation and exemplified by some batch and dynamic (titration) systems of a different degree of complexity.
Some elementary rules of conservation are interdependent. This interdependency of the resulting balances and formulation of the set of independent relationships will be considered with the help of some examples, where the complex nature of the system, exemplified by the formation of aqua-complexes by both ionic and neutral species, will also be taken into account. Among others, the dynamic system is exemplified by titration of KIO3 + HCl + H2SeO3 + HgCl2 with ascorbic acid (C6H8O6). The degree of complexity of this system is evidenced by more than 40 equilibrium constants involved in the related balances.
Keywords: conservation laws, chemical thermodynamics, electrolytic systems, ionic equilibria.
Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław
1 Zakład Dydaktyki Chemii, Wydział Chemii UAM, ul. Grunwaldzka 6, 60-780 Poznań
2 Zakład Dydaktyki Chemii, Wydział Chemii UMCS, Plac Marii Curie Skłodowskiej 3, 20-031 Lublin
3 Zakład Dydaktyki Chemii, Wydział Chemii UJ, ul. Ingardena 3, 30-060 Kraków
The article describes the research in chemical education carried out in Poland and its significance for improvement of chemical education on each level, as well as for the general development of learners and their future career choices. The research was carried out in cooperation with world scientific centers through, participation of polish researchers in international conferences, organization of cyclic international meetings, carrying out many years' standing common research, and taking part by the university and PhD students in European exchange programs. Particular attention has been paid to the importance of information technology development, including for instance e-teaching. It has been proven that research in chemical education contributes to elaboration of theoretical assumptions concerning teaching processes. The results are now aimed at their application in chemistry teaching and learning efficacy improvement.
Keywords: chemistry, chemical education, information technology, multimedia text-books.
Wydział Chemii, Uniwersytet Warszawski, ul. Pasteura 1, 02-093 Warszawa
Reversible deposition of magnesium on electrodes and its anodic dissolution in non-aqueous solvents are possible only from particular electrolytes, like ethereal solutions of Grignard reagents or recently elaborated complexes of alkylaluminum chlorides with dialkylmagnesium. The above processes are important in developing rechargeable magnesium batteries but can also help organic chemists for deeper understanding of the formation of Grignard reagents in classic reactions.
Magnesium deposition from solutions of Grignard reagents has been known for more than 80 years but repeated efforts to explain the reason of reversibility and find other suitable electrolytes were unsuccessful for a long time. Recently, a sig-nificant progress was achieved due to the application of modern spectroscopic
methods combined with electrochemical measurements. These results are presented. They include a finding of Liebenow [27, 28] that the magnesium dissolution strongly depends on the morphology of depositions and conclusions from reports of Aurbach and coworkers [12, 32-42] which explained in detail characteristics of the magnesium surface in a contact with different electrolytes, the role of adsorption of ions and radicals in electrode processes and the nature of electro-active species in various solutions. Finally, the proposed electrode mechanism of the magnesium deposition and dissolution from different electrolytes, shown in Scheme 2 and reactions (12)-(16), is presented.
Keywords: magnesium electrode processes, organomagnesium ions, Grignard compounds, magnesium organochloroaluminates, adsorption, rechargeable batteries.
Uniwersytet Marii Curie-Skłodowskiej, Pl. Marii Curie-Skłodowskiej 3, 20-031 Lublin
This paper reviews wetting phenomena in relation to different types of solids and human skin in the presence of surfactants. Wettability of solids by surfactants is important for many technological applications. The addition of surfactants is necessary to achieve a better wettability of a given solid.
In the first part of this article the definition of a contact angle and an interfacial tension along with methods of their determination is presented. Next, a relationship between a liquid--air, a solid-air and a solid-liquid interfacial tensions and wettability of solids is shown.
Three types of wetting are discussed in this work: a spreading wetting, an adhesional wetting, and an immersional wetting. Wettability forces of hard surface and powders are also described in this part of the article.
In the third part of the article main aspects related to the solids critical surface tension of wetting are presented. Different problems of solids' wetting critical surface tension are described, since there is still no unambiguous method to determine this value.
Later, based on the Lucassen-Reynolds equation we described the dependence between the adsorption of surfactants at the interfaces, mainly in a solid-water-air systems and wetting of solids, because they are both strongly related. From this equation the slope of a plot of γLVcosθ (adhesion tension) versus γLV (surface tension) gives us the information about the surface concentration of the surfactant at water-air and a solid-water interfaces in a solid--water-air system including both non-polar (low-energy) and polar (high-energy) solids. We have also shown that in the case of hydrophobic solids, for several types of surfactants, there is a constant negative slope of γLV cosθ-γLV curve. However, for high-energy polar solids the positive slope of this curve is observed and there is no linear dependence between adhesional and surface tension. Thus, for a high energy solid-aqueous surfactant solution-air systems it is difficult to establish synonymous mutual relationships between the adsorption of surfactant at a solid-air, a solid-liquid and a liquid-air interfaces and wettability of high-energy hydrophilic solids.
At the end we presented main problems dealing with wettability of human skin surface, which is the most important factor of the skin protective function. It minimizes water loose, prevents entry of a foreign matter and chemicals, and defines smoothness and elasticity of the skin. Surprisingly, this subject has received a little attention in the literature.
The human skin surface, after the extraction of sebum (skin surface lipids) belongs to hydrophobic surfaces (low-energy) in terms of critical surface tension and polar and dispersion components of a free surface energy. El-Shimi and Goddard compared the skin surface with polymer surfaces such as polyvinylchloride, polytetrafluoroethylene and polyethylene, but we have to remember that the human skin is a living matter and in the presence of sebum becomes hydrophilic. In order to remove this fatty film from the skin surface cleansing products, which contain many various surfactants, are used. Good wetting and cleansing effects of such products depend on surfactants ability to adsorb on the skin surface and reduce an interfacial tension at water-skin interface in skin-water-air system.
Keywords: wettability, critical surface tension of wetting, adsorption, human skin, surface active agents.
Zakład Chemii Surowców Kosmetycznych, Katedra Kosmetologii, Wydział Farmaceutyczny,
Uniwersytet Medyczny w Łodzi, ul. Muszyńskiego 1, 90-151 Łódź
Skin cancer is the most often encountered malignant cancer which stands for about 1/3 of all medically confirmed cancers. Number of patients with diagnosed cancer of this type increases annually by 10 to 15%. Skin cancer belongs to the group of malicious in situ cancers, which hardly develops metastasis to other organs. Nevertheless considering the frequency of occurrence and localization, its importance should not be disregarded. The most often occurring skin cancer is basal cell carcinoma (BCC), which stands for about 65-75% of all skin cancers and about 25% of all diagnosed cases of cancer. Second most encountered skin cancer is squa-mous cell carcinoma, which constitutes 20-30% of all skin cancers, while malicious melanoma only 1.5-2%. Oncological surgery and radiotherapy are the most popular treatments of skin cancer, while chemotherapy is less applied. Results of the first two methods are comparable. Differences refer to frequency of occurrence, side effects, treatment and cosmetic effects having influence on the quality of patients' life. Third type of skin cancer - malicious melanoma - belongs to the group of the most aggressive, which hardly undergo treatment. The cytostatic drug being most active in monotherapy of melanoma is decarbazine. Other substances that demonstrate some/partial activity in treatment of malicious melanoma are: temozolomide, cis-platin, carboplatin, vinblastin, vincristine, paclitaxel, docetaxel.
Keywords: chemotherapeutics, skin cancer
*Instytut Chemii i Technologii Organicznej, Wydział Inżynierii i Technologii Chemicznej,
Politechnika Krakowska, ul. Warszawska 24, 31-155 Kraków
** Katedra Ochrony Roślin, Wydział Ogrodniczy, Akademia Rolnicza, Al. 29 Listopada 54, 31-425 Kraków
Plant secondary metabolites have been used for thousands of years as pharmaceuticals and dyes or as natural pesticides. Furanocoumarins are one of the more important secondary metabolites of many plants. Many sorts of furanocoumarins are known. Psolaren and its derivatives belong to them.
Linear furanocoumarins have been isolated from wild and garden plants (Umbelliferae, Apiacae, Leguminosae). The increase of psolarens content (even dozens as much) in plants may be caused both by pathogenic bacterium or virus infection and by insects attack. This effect is used to obtain these compounds.
The psolaren and its derivatives can also be prepared by the synthetic way. It is realized in the consequence of two-reaction pathway: (1) by the construction of the carbon framework from three condensed rings (starting from suitable derivatives of the resorcin) and (2) by the chemical modification of substituents. The combination of these methods allows us to synthesize the majority of naturally occurring psolarens and its derivatives characterized by considerable biological activity.
Psolaren and its derivatives (linear furanocoumarins) are used in dermatology for treatment of skin diseases such as vitiligo and psoriasis. They have also been used as probes of nucleic acid structure and function.
Psolaren demonstrates high activity towards UV. Its therapeutic activity and biocidality is caused by reactions that takes place in these conditions. Psolarens, in the presence of UV, interact with DNA inhibiting its replication.
Keywords: plant secondary metabolites, psolarens, furanocoumarins
Wydział Chemii Uniwersytetu Warszawskiego, ul. Pasteura 1, 02-093 Warszawa
The history of the physical chemistry at the Faculty of Chemistry of the Warsaw University in XXth century, with main attention to its second part is presented. The organizational, scientific and teaching aspects are discussed. The list of che-mists, who have been working in the past and who are currently working in physical chemistry is attached.
Keywords: physical chemistry, Faculty of Chemistry, Warsaw University, history of physical chemistry
Wydział Chemii Uniwersytetu Wrocławskiego, ul. F.Joliot-Curie 14, 50-383 Wrocław
1ICh PAN, Warszawa, 2IIM AGH, Kraków
Wydział Chemii, Uniwersytet Jagielloński, ul. Ingardena 3, 30-060 Kraków
The present paper describes the activation of organic molecules containing multiple bonds by donation of electrons to π* antibonding orbitals of the molecules. The data concerning the adsorption of alkenes (ethene, propene, cis-but-2-ene, trans--but-2-ene), acetylene, benzene, acetone, and formaldehyde on Cu+ sites in zeolites CuX, CuY, and CuZSM-5 will be presented. The spectroscopic IR data, as well as the results of quantum chemical DFT calculations will be considered. Both IR studies and DFT calculations evidenced a weakening of C=C and C-C bonds. IR red shift reaches 78-115 cm-1 for C=C band and 168 cm-1 for acetylene. Moreover, in the case of ethene and acetylene the stretching modes of the C=C and C-C bonds which were IR inactive in free molecules became IR active when interacting with Cu+, indicating the loss of symmetry. On the contrary, the C=C stretching in trans-but-2-ene was still IR inactive when trans-but-2-ene interacted with Cu+. At high loading some Cu+ ions were able to bond two alkene molecules. Although the activation is small, it occurs also for aromatic C-C bond in benzene adsorbed on Cu+ site; the red band shift was 13 cm-1 i.e. much less than in the case of alkenes and acetylene. Similarly, the activation of C=O bond in acetone and formaldehyde inter-acting with Cu+ also results in the red band shift of 38 and 56 cm-1.
All the systems have been studied by DFT modeling which reveals the function of zeolite as a host for transition metal cationic centres which act as electron transmitters. Flow of electrons and subsequent activation is determined by the electronic structure of the molecules, their electron affinity and symmetry as well as the ability of a site to π-backdonation.
Keywords: IR spectroscopy, Cu+ cations, DFT calculations, zeolites CuX, CuY, CuZSM-5
Politechnika Szczecińska, Wydział Technologii i Inżynierii Chemicznej,
Instytut Chemii i Podstaw Ochrony Środowiska, Zakład Analizy Instrumentalnej
Aleja Piastów 42, 71-065 Szczecin
The interest in the microwave assisted organic synthesis has been growing during the recent years. It results from an increasing knowledge of fundamentals of the dielectric heating theory, availability of an equipment designed especially for the laboratory use as well as the discovery of the special techniques of the micro-wave syntheses.
There are two different mechanisms of transformation of microwave energy into heat [6, 38-39]. The first one is the dipolar polarization. The electric field of electromagnetic irradiation causes such a change in the polar molecules orientation, that they align their dipole moments with the force field lines (Fig. 1). Another way of the microwave - molecule interaction that leads to heat evolution bases on the ionic conduction phenomenon. It originates from a presence of ionic species in the materials. Under the influence of the alternating dielectric field ions start to move through the solution, resulting in an increased collision rate, and the kinetic energy is converted into heat (Fig. 2).
The microwave activation in organic synthesis leads to considerable acceleration of a chemical reaction as compared to the traditional thermal process. It originates from the thermal effects, i.e. a change of the temperature profile during the process, the existence of so-called "hot spots" and the ability of solvent heating above its normal boiling point as well as the specific (no thermal) effects, connected with a change of the activation energy of the reaction and the activity of molecules .
Moreover, microwave irradiation can also change direction, yield and selec-tivity of a chemical reaction. The extent of these changes depends on a solvent pola-rity and polarity of the ground and transition states of reagents (Fig. 3-5) .
The microwave syntheses are performed in multimode or single-mode cavities, with respect to the mode of the irradiation distribution over the working compartment [3, 4, 38]. The most popular techniques of microwave enhanced syntheses are as follow: syntheses in a solvent, solvent-free syntheses and supported syntheses. The application of one of them depends on the solvent and/or reagents properties as well as the reaction conditions [3, 38].
Keywords: microwave irradiation, microwave assisted organic synthesis, dielectric heating, microwave equipment, microwave techniques
Wydział Mechatroniki Wojskowej Akademii Technicznej
ul. Kaliskiego 2, 00-908 Warszawa
Explosives are chemical compounds or mixtures which, under the influence of an external energetic stimulus of sufficient intensity, develop a rapid exothermic reaction generating large quantity of gas at very high pressure and temperature. Explosives are a chemical energy source of high power (quantity of energy released in a time unit) and high density (quantity of energy per unit of volume). From the application point of view, explosives are divided into blasting, propelling and initiating ones. Of these, blasting explosives are the most common and their production worldwide reaches many millions of tons a year. Detonation is the basic form of their explosive transformation. It can be started by a relatively intense energetic stimulus, for example by a disruptive or other detonator. The linear velocity of propagation of explosive's chemical decomposition during detonation (detonation velocity) reaches several thousand meters per second. During detonation of a blasting explosive, the pressure of detonation products reaches the level of several GPa for mining explosives and as much as 50 GPa for the most powerful military explosives. The detonation pressure value is the measure of an explosive's brisance. It is the brisance that is used to destroy (crush) the structure of a medium.
Due to the fast development of mining industry, the demand for effective, safe and inexpensive mining explosives was growing. In the mid-fifties of the 20th century new types of blasting explo-sives appeared on the US market without typical explosive material as part of the composition. The materials were a mixture of ammonium nitrate as oxidant (base ingredient) and an organic or inorganic combustible ingredient. Within a short time, ammonium nitrate fuel oil (ANFO), a mixture of granulated ammonium nitrate and fuel oil characterized by a good flow handy in use, became the most widely used material. Nowadays, ANFO makes more than half of all explosives used in the mining industry worldwide. Simultaneously, another revolutionary innovation was introduced - substantial quantity of water, previously regarded as an ingredient that ruined the explosive properties of mixtures, was purposefully added to the explosive composition. The resulting slurry and emulsion explosives containing a saturated water solution of ammonium nitrate had a semi-liquid consistency, which made it possible to mechanise their manufacture and to load boreholes with explosives on the mining site.
The author has specified new, safe varieties of explosives which do not contain typical explosive compounds, with ammonium nitrate as a predominant ingredient. They are named "third generation explosives", the first generation being black gunpowder used for a millennium as the versatile explosive and the second generation being explosive chemical compounds (mostly nitrocompounds, aromatic nitroamines and the esters of nitric acid(V) and aliphatic polyalcohols).
In Poland, a research on new varieties of third generation explosives was started in the early 1970s at IPO (ammonium nitrate type) and at WAT (slurry and emulsion type). Based on the research, several modern versions of explosives were developed and brought into production to be used subsequently in the country's open and underground pits.
The paper presents the basic historical developments in the field of mining explosives, from black gunpowder to modern safe materials devoid of explosive constituents. Based on the author's own research, the physical and chemical properties of third generation explosives have been characterized in depth, such as ANFO, slurries and emulsions. Particular attention has been paid to the physical structure of mixtures, which plays a key role in determining their explosive characteristics.
Keywords: mining high explosives, history of development, explosive properties
Zakład Chemii Surowców Kosmetycznych
Wydział Farmaceutyczny Uniwersytetu Medycznego w Łodzi, ul. Muszyńskiego 1, 90-151 Łódź
Gallium(III) salts have been explored for their antineoplastic properties since 60. of XX century, but clinical experience has revealed unfavorable toxicological and pharmacokinetic properties. Much of the present knowledge about the biodistribution of gallium compounds stems from the application of gallium radionuclides in tumor diagnosis. Half and century ago, when the affinity of gallium for bone was recognized, the use of gallium(III) radionuclides for diagnosis and radiotherapy of osteogenic sarcoma was first proposed. However, interest in the broader potential of gallium in tumor therapy has only been stimulated by the discovery of the antineo-plastic properties of cisplatin and the observation of a tendency of gallium to accumulate in various tumors, soft tissues and sites of inflammation. The concept of
an investigation of antineoplastic gallium(III) complexes are essentially derived from experience with gallium(III) nitrate and chloride. Attempts to improve the pharmacological effects by changing the way of administration were granted insufficient success to justify further investigation as cancer therapeutics. However, recent years have seen renewed interest in gallium compounds, because the oral application of gallium(III) complexes with organic ligands has been recognized as a way to overcome the limitations of gallium(III) nitrate and chloride. Two of these gallium(III) complexes - gallium maltolate and KP46 - have reached the clinical trials. Gallium(III) complexes based on other ligands are noticeably underexplored.
Keywords: gallium(III) salts, gallium(III) complexes, antineoplastic properties
Zakład Chemii i Techniki Radiacyjnej, Instytut Chemii i Techniki Jądrowej, ul. Dorodna 16, 03-195 Warszawa
Motivation of the present paper is the new interest in the so called "cold fusion" of deuterium. The author, former electrochemist and presently a radiation chemist, was involved in writing a paper expressing criticism toward original Fleischmann and Pons , next called F&P "discovery", after experimental trials performed to repeat the claims. Actual efforts to revive an old idea of the D+D reaction in palladium electrode during electrolysis of heavy water consist in application of a new kind of palladium cathode, additional electric and magnetic fields around the electrolytic cell and experiments with polymeric detector, supposed to show nuclear disintegration of palladium and other strange nuclear transmutations. These new approaches to the almost twenty year old idea did not bring revelations in the field of energetics, therefore the nowadays reaction of popular media is far less enthusiastic than the original outburst of curiosity after the F&P paper. The author of the present paper analyses the artifacts and wishful thinking approach seen in publications, indicating that the problem of cold fusion is still unsolved, as it was at the beginning. The whole field belongs to the category of pathological science, like previously polywater, water with the memory of the solute present before dilution, etc..
However, almost all other cases of pathological science have died quietly, the remaining interest in cold fusion asks for an explanation. The international conferences devoted to cold fusion convene frequently every second year or every year, the only change is, that recently the term cold fusion is no longer used but is substituted by enigmatic LENR (low energy nuclear reaction) and CANR (chemically assisted nuclear reaction). In the meantime between different versions of F&P approaches, another cold version of D+D fusion in perdeuterated acetone appeared as so called sonofusion, lasting as pathological science even shorter.
Financial support for cold fusion still exists, sometimes by organizations that wish to remain anonymous. The author of the review draws attention to the fact, that presently the majority of affiliations of authors of papers, and financial supports of civil laboratories are connected with military (USNavy) research and more general weaponry research, like in the case of DARPA (Defense Advanced Research Project Agency). The reason is probably a hope, that creation of a true neutron bomb can be achieved, because the actual one is an ordinary nuclear device with enhanced yields of neutrons only. Vivid interest in cold fusion in Japan is connected with the fear, that some nuclear achievements may escape the attention, as it was the case of what happened in 1945.
The last but not least reason for the interest in cold fusion are the controversial European projects of ITER and HiPER trying to develop the high temperature fusion power plants, with an active zone of nuclear reaction heated to 100 million degrees K. Among many unsolved objections, the link between that zone and economic production of electric current is prohibited by actual physical and chemical laws. Therefore physicists involved in the projects are aware of difficulties and express interest in approaches to cold fusion ideas, especially in chemical aspects connected with solving, perhaps, difficult problems, e.g. from the area of material science.
Keywords: cold fusion, deuterium-deuterium fusion, ITER, HiPER, military research, polywater, sonofusion, thermonuclear energy
ul. J. Bytnara 23 m. 19, 02-645 Warszawa, (Em. profesor Uniwersytetu Warszawskiego)
The ancient alchemy is characterized as a general philosophy of Middle Age. Its part was the primitive chemistry. The main feature of alchemy was the holistic view on the nature including human beings. In XVII c. the holistic view was replaced by the reductionism introduced by Descartes. Now-a-days we return to the holistic view. In chemistry it is illustrated by the synergism. This is the Modern Alchemy.
Keywords: alchemy, modern alchemy, philosophy, holism, reductionism
Wydział Chemii, Uniwersytet Warszawski, ul. Pasteura 1, 02-093 Warszawa
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