A comparative study of the relative antioxidant activity (RAA) of fullerene С 60 and its amino acid derivatives is performed via amperometry and fluorimetry. The sizes of nanoparticles in the corresponding colloidal solutions are determined via dynamic light scattering (photon correlation spectroscopy) to study the effect the steric factors of the investigated compounds have on the magnitude of the RAA. Data are subjected to statistical correlation regression analysis using results obtained for the RAA dependence of fullerene С 60 and salt forms of its acid derivatives on the corresponding sizes of nanoparticles in colloidal aqueous solutions. A close negative (inverse) correlation is identified between the size of nanoparticles in a solution and their antioxidant properties, with a pronounced synergic effect related to the influence of both chemical structure of the studied compounds and their structural organization in colloid solution. It is found that the structure of a substituent in a molecule of amino acid derivative of fullerene С 60 also influences the size of the forming nanoparticles. At the same time, reductive properties of amino acid derivatives of fullerene С 60 are generally determined by the electron effects of substituents.

Self-assembly of monostyryl dye of benzothiazole series with symmetric and asymmetric bisstyryl dyes based on dibenzo-18-crown-6 ether has been studied by optical and NMR spectroscopies. The photoinduced energy transfer between monoand bisstyryl dyes in supramolecular assembly has been analyzed. The cascade energy transfer in the supramolecular complex of monostyryl dye with asymmetric bisstyryl dye has been suggested.

2,2′: 5′,2″-Terthiophene derivative containing benzo-18-crown-6 fragments linked through ethene spacers was synthesized, and its complexation with octane-1,8-diaminium diperchlorate in acetonitrile was studied by spectrophotometric titration, 1 H NMR, and mass spectrometry. The 1: 1 stoichiometry of the complex was confirmed by mass spectrometry, and its structure was proposed on the basis of the 1 H NMR data.

Condensation of o-(diphenylthiophosphoryl)aniline with 8-formyl-7-hydroxy-4-methylcoumarin yields the Schiff base capable of acting as a tridentate monoanionic ligand upon coordination with the ReI and PdII ions. The corresponding palladium complex shows high catalytic activity in the Suzuki cross-couplings of aryl bromides with phenylboronic acid. The analogous P(O)-substituted ligand was not isolated in the pure form; however, using template-assisted method, its κ3-O,N,O-zinc complex was synthesized; this complex is luminescent in the MeCN solution at 20 ℃.

The results of optical and NMR spectroscopy studies showed that crown-containing styrylphenantrolines can form molecular assemblies in the presence of metal ions of different nature. The composition and structure of the assemblies can be controlled using the laws of complexation. It was found that zinc complexes with styrylphenantrolines are fluorescence ligands for metal cations that can coordinate to free crown ether fragments of the styrylphenanthroline molecules.

Multicomponent molecular assemblies of 15-crown-5-containing 4-styrylpyridine with phthalic acid in the presence of potassium perchlorate were studied. The structure of the obtained complicated assemblies was determined by 1H and 13C NMR spectroscopy, UV spectroscopy, and X-ray analysis. The composition of the supramolecular complexes was established by spectrophotometric titration, and the stability constants were calculated. The quantum yields of fluorescence for the ligand and its complexes of various nature were determined.

Novel unsymmetrical SCS'-pincer ligands, 1-[PhNHC(S)]-3-[Ph(2)P(S)NH]-C(6)H(4) (3) and 1-[PhNHC(S)]-3-[Ph(2)P(S)O]C(6)H(4) (7), bearing a thiocarbamoyl moiety in combination with thiophosphorylamino- and thiophosphoryloxy-donating groups, respectively, were obtained via thiophosphorylation of 3-amino- and 3-hydroxy-benzoic acid (thio)anilides 1 and 6. Direct cyclometallation of the central benzene ring in the ligands 3 and 7 in reaction with (PhCN)(2)MCl(2) (M = Pd, Pt) as a metal precursor afforded κ(3)-SCS'-hybrid pincer complexes 8, 9 with 5- and 6-membered fused metallacycles in good to high yields (67-95%). The complexes 8 and 9 were characterized by multinuclear NMR ((31)P, (1)H, (13)C) and IR spectroscopy as well as single-crystal X-ray crystallography. Palladium complexes 8a and 9a were shown to be active catalysts for the Suzuki-Miyaura cross-coupling reaction. In the solid state the ligands 3 and 7 as well as their Pt(II) and Pd(II) complexes 8 and 9 are luminescent at 300 K. The emission of the complexes has the different origin depending on the metal nature.

Complex formation of 15-crown-5 ether containing monoand bis(styryl)bipyridine with transition metal perchlorates was studied. The complex stoichiometry, complex structure and stability constants were determined by electronic spectroscopy. The influence of metal ions on occurrence of E,Z-isomerization was analyzed; the optical characteristics of two isomers were calculated from the photolysis data.

Complex formation of 18-crown-6-2-styrylbenzothiazole and a crown-containing benzothiazolquinoline derivative with alkaline earth metal perchlorates was studied. The structures and stability constants of the complexes were determined.

The reversible photochemical E—Z-isomerization of crown-containing 4-styrylpyridine was studied. The reaction was carried out in the presence of alkaline-earth metals capable of forming complexes with the crown-ether fragment and heavy metal perchlorates (Hg2+, Cd2+) that are able to coordinate the nitrogen atom of the heterocyclic residue. The influence of complex formation on the E—Z-photoisomerization was determined by electronic spectroscopy and 1H NMR spectroscopy. The studies performed confirm that the E—Z-photoisomerization can be controlled using supramolecular complex formation.

In the presence of Ba 2+ ions, (benzothiazolyl)ethenylbenzocrown ether forms the stable sandwich complex 2L⋅Ba 2+ with an unusual structure, in which the benzothiazole fragments are arranged one above the other. Irradiation of the sandwich complex with visible light induces stereoselective [2+2] cycloaddition giving rise to two “head-to-head” isomers of biscrown-cyclobutane. The addition of dibasic dicarboxylic acids that additionally stabilize the sandwich complex in a favorable conformation affects the isomer ratio of the cyclobutanes formed. The conformational equilibria for the sandwich complex and cyclobutanes were studied by 1 H NMR spectroscopy.

Optical and x-ray experiments showed the possibility of studying 4-styrylpyridine with a 15-crown-5 ether fragment to bind metal cations through the participation of two centres: the crown ether moiety and the heterocyclic part. The metal cations studied can be divided into three groups. Alkaline earth metal cations form complexes with the crown ether centre, H+, Co2+ and Cd2+ prefer coordination with the N-atom of heterocyclic part and Hg2+ cations form complexes through coordination with both binding centres. Copyright (c) 2005 John Wiley & Sons, Ltd.

Benzobisthiazole-based bis(crown ether) was synthesized and its complexation with alkali and alkaline earth cations was studied. Photochemical transformations of the free ligand and its complexes with alkaline earth cations involve E,Z -photoisomerization and [2+2] photocycloaddition.

Enteropeptidase (enterokinase, EC 3.4.21.9) hydrolyzes peptide bonds formed by carboxyl groups of Lys or Arg residue if less than four negatively charged amino acid residues are in positions P2–P5 of its substrate. We determined the kinetic parameters of three substrates of this type: human angiotensin II (AT) (DR ↓ VYIHPF) and the Hb(2–8) (LTAEEK ↓ A) and Hb(1–9) (MLTAEEK ↓ AA) peptides of the cattle hemoglobin β-chain. The Km values for all the substrates (≈10–3 M) were one order of magnitude higher than those of the typical synthetic substrates of enteropeptidase or chimeric proteins with the –DDDDK– full-size linker (Km ≈ 10–4 M). The kcat values for AT and Hb(2–8) were also close and low (≈ 30 min–1). The general hydrolysis efficiency of such substrates is no more than 1% of the corresponding value for the typical peptide and protein substrates of the enteropeptidase. However, the elongation of Hb(2–8) peptide by one amino acid residue from both its N- and C-termini results in a dramatic increase in the catalytic efficiency of the hydrolysis: the kcat value for Hb(1–9) is 1510 min–1, which means that it is hydrolyzed only three times less effective than the chimeric protein with the full-size linker.

A new technique was developed for the analysis of peptide compositions of extracts from various animal and plant tissues. It involves the acidic extraction of a peptide fraction from the starting material and its precipitation with acetone, fractionation of peptides by ion-exchange chromatography by using a stepwise elution of fractions and detection by means of ninhydrin color reaction, and computer processing of the results. For the presentation of the results of analysis, chromatographic profiles and peptidograms were proposed. The results of analysis can be stored in a database and used for the creation of "generalized peptide portraits" and "differential peptide portraits" of the subjects investigated, which allow the identification of peptides characteristic of the subjects. The amount of peptide undergoing analysis ranged from 1 to 10 nmol.

With the aim to investigate structure-functional relations of DSIP, 11 DSIP analogues were tested on antimetastatic activity, among them five new analogues, differing in positions 2 and 6 of the DSIP amino acid sequence were synthesized by the solid-phase method using Fmoc-approach. Experiments on C57B1 mice with metastatic Lewis lung carcinoma showed some analogues to be more efficient as antimetastatic agents then DSIP after i.v. (50 micrograms/kg) administration. Normalization of neuroendocrine status and activity of peritoneal, alveolar and spleen macrophages after the DSIP and some analogues injections in mice with metastatic Lewis lung carcinoma took place. Antimetastatic action of DSIP derivatives is considerably affected by structural changes, especially in the N-terminal part. Conformational factors rather than enhanced enzymatic resistance are essential for antimetastatic response.