Oskar I. Koifman

First tellurium-containing phthalocyanine analogues: strong effect of tellurium on spectral, redox and conductivity properties of porphyrazines with annulated chalcogenodiazole ring(s)

The first tellurium-containing phthalocyanine analogues have been prepared and spectroscopically characterised: the Mg(II) complex of tetra(1,2,5-telluradiazolo)porphyrazine and a low-symmetry tert-butyl substituted Mg(II) tribenzoporphyrazine with one fused 1,2,5-telluradiazole ring. It was observed that the introduction of Te atom(s) reduces the energy of the Q-transition, facilitates the reduction of the macrocycle and strongly increases the conductivity of thin films.

Mesogenic 4-(ω-Hydroxyalkoxy)-4'-formylazobenzenes

Homologs from a series of 4-(ω-hydroxyalkoxy)-4-formylbenzenes (C2,C3,C4,C6 ,C8) were synthesized. All compounds obtained show properties of thermotropic nematic liquid crystals. The effect of the terminal hydroxy group of the end substituent on the mesomorphous properties of the compounds was analyzed.

Phenyl-substituted porphyrins: III. Relative reactivity in the nitration reaction

Study on the nitration of phenyl-substituted porphyrins showed that protonation of the porphyrin macroring does not affect the relative reactivity of the meso- and β-positions and phenyl groups.

Synthesis and properties of lanthanide complexes with tetrapyrazinoporphyrazine and its substituted derivatives

Reactions of dicyanopyrazine and its tert-butyl-, diphenyl-, and dipyridyl-substituted derivatives with erbium, thulium, ytterbium, and lutetium chlorides, acetates, and acetylacetonates gave the corresponding tetrapyrazinoporphyrazine metal complexes which were characterized by elemental analyses, and IR, 1H NMR, and electronic absorption spectra. The stability of the complexes to thermooxidative decomposition in air was also studied.

Bromination of 5,10,15,20-tetraazaporphin magnesium complex

Bromination of 5,10,15,20-tetraazaporphin magnesium complex with N-bromosuccinimide in ethanol proceeds with the formation of a mixture of brominated derivatives containing up to 7 bromine atoms in the molecule. The magnesium complex of monobromotetraazaporphin was isolated and characterized. According to quantum-chemical calculations the bromination proceeds as the radical substitution of a hydrogen atom in the macrocycle.

Mesogenic 4-acryloyloxy- and 4-(2,3-epoxypropoxy)phenyl 4-alkoxybenzoates

Procedures were developed which made it possible to synthesize in good yields homologs of 4-acryloyloxyphenyl 4-alkoxybenzoates (C3, C5, C7, C8) and of 4-(2,3-epoxypropoxy)phenyl 4-alkoxybenzoates (C5, C7). The substituted phenylbenzoates obtained exhibit the enantiotropic nematic mesomorphism in a sufficiently wide temperature range. The studied compounds have absorption maxima in the near UV region and a high temperature of decomposition beginning.

Study of Intermolecular Interaction of Mg-5,15-Di(o-methoxyphenyl)-2,8,12,18-tetramethyl- 3,7,13,17-tetrabutylporphin with o-Xylene Organic Peroxides. Effect of Imidazole on the Reaction Kinetics

Using the method of spectrophotometric titration a reaction of magnesium porphyrinate with the o-xylene organic peroxides was investigated, the reaction mechanism and kinetic parameters were determined. The effect of imidazole on the rate of the reaction under investigation was demonstrated. The presence of steric strain in the magnesium porphyrinate macrocycle and its increase in the course of formation of intermediates was observed.

Direct catalytic arylation of heteroarenes with meso-bromophenyl-substituted porphyrins

The arylation of mono-, di- and tetra-meso-bromophenyl-substituted porphyrins with the heteroarenes containing “acidic” C–H bonds, such as benzoxazole, benzothiazole and N-methylimidazole was studied in the presence of three alternative catalytic systems: Pd(dba)2/DavePhos/Cs2CO3, Pd(PPh3)4/PivOH/K2CO3 and Pd(OAc)2/Cu(OAc)2/PPh3/K2CO3. The first catalytic system was found to be successful in the reaction with benzoxazole, the second one was less efficient for our purpose, while the third system proved to be most versatile and afforded corresponding mono-, di-, tri- and even tetraarylated derivatives of porphyrins.

Electrophilic substitution in meso-phenylporphyrins

Electrophilic substitution reactions in the meso-phenylporphyrins are described. The relative reactivity of the various positions of the porphyrin cycle to attack by electrophiles was discussed.

Viscosity of dilute solutions of styrene copolymers in the course of polymer-analogous transformations

The properties of dilute solutions of styrene copolymers and their porphyrin derivatives prepared via the functional group transformations have been studied in DMF at 20–35°C. The effect of the copolymer composition, on the intrinsic viscosity, the Huggins constant, the macromolecule dimensions, and thus on the interaction with solvent has been elucidated. The nature and content of functional groups in the polymer influence the behavior of macromolecule coil in the solution. Introduction of the porphyrin fragment loosens the macromolecular coil, but does not qualitatively change the solution behavior.