Sergei A. Syrbu

Phthalocyanine conjugates with carbohydrates: synthesis and aggregation in aqueous solutions

The review is focused on the current state of the synthesis of glycosylated phthalocyanines and their precursors, mono-, di-, and tetraglycosyl phthalonitriles. Features of the synthesis of phthalogen conjugates with carbohydrates and the formation of related metal phthalocyanine complexes are discussed. The formation of aggregates of phthalocyanines in various media exerts a significant effect on the physicochemical and photochemical properties of phthalocyanine macrocycles, which is especially important in the practical use of phthalocyanines as photosensitizes. An aggregation of phthalocyanine conjugates in aqueous solutions strongly decreases the quantum yield of singlet oxygen, thus diminishing the biological activity of these compounds. Specific features of phthalocyanine conjugate aggregation with carbohydrates in aqueous solutions, organic solvents, and some their mixtures are analyzed.

Acid–base equilibria and coordination chemistry of the 5,10,15,20-tetraalkyl-porphyrins: implications for metalloporphyrin synthesis

A spectrophotometric study of the acid–base equilibria and complexation with metal ions has been carried out for 5,10,15,20-tetrakis(trifluoromethyl)porphine and 5,10,15,20-tetrakis(iso-buthyl)porphine in acetonitrile solutions. Protonation and deprotonation of these porphyrins was found to be stepwise with sequential formation of mono- and doubly protonated/deprotonated species. The overall basicity and acidity constants have been determined. The porphyrin complexation with Zn2+ and Cu2+ ions was studied and the rates constants of the macrocycle metallation have been determined. The structure–property relationship derived from the metal chelation studies and the prospects for the use of the above systems for the design of highly sensitive sensors for metal ions were discussed in detail.

Synthesis of meso-mono-phenylporphyrins with active groups in the benzene rings

The mono-meso-allyloxy- and acrylamidophenylporphyrins were synthesized from the corresponding hydroxy- and aminophenylporphyrins. All the compounds were characterized by IR, UV-Vis, 1H NMR and mass spectra.

Reactivity of phthalocyanine precursors

A higher reactivity of 4-nitrophthalonitrile as compared to phthalonitrile and 4-amino-phthalonitrile in the reaction with sodium methoxide in methanol was demonstrated by theoretical (semiempirical, ab initio calculations) and experimental methods. The regioisomeric composition of substituted methoxyiminoisoindolenines was studied by analysis of products of their reaction with p-toluidine. The higher reactivity of 3-imino-1-methoxyisoindolenine as compared to 1,3-diiminoisoindoline in the reactions with nucleophilic agents (ammonia, p-toluidine) was shown by semiempirical calculations and kinetic methods.

Kinetic stability of tetra(1,2,5-thiadiazolo)porphyrazine in the system nitrogen-containing base-dimethyl sulfoxide

The behavior of tetra(1,2,5-thiadiazolo)porphyrazine in dimethyl sulfoxide has been studied, and fairly high stability of the resulting proton-transfer complex has been revealed. The complex is kinetically unstable in strongly basic media. The effects of the nitrogen-containing base and NH acidity of the porphyrazine macrocycle on the rate and activation parameters of decomposition of the proton-transfer complex have been estimated.

Synthesis and coordination properties of nitro derivatives of 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrin

Methods were developed for the synthesis of nitro derivatives of 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrin containing nitro groups at the meso positions of the porphyrin core and at the para positions of the phenyl substituents. The formation kinetics of the zinc, copper, and cobalt complexes of the resultant porphyrins in pyridine and in an acetic acid–benzene (7 : 3) mixed solvent was studied. It was found that the properties of the porphyrin ligands are determined both by the electronic effect of the nitro groups and by the effects of spatial distortion of the porphyrin core.

Synthesis and Complex Formation of Porphyrin Polymers on the Basis of Methyl Methacrylate

Copolymers of methyl methacrylate with various porphyrin monomers were prepared by radical copolymerization in solution. The yields, molecular weight characteristics of the copolymers and the molar content of porphyrin in the copolymers were determined. Copper and zinc complexes of the synthesized porphyrin polymers were obtained.

Porphyrin acidity and metal ion coordination revisited: electronic substitution effects

Macrocycle acidity and Zn2+ ion coordination are reported for three porphyrin derivatives which differ in both steric and electronic substitution effects on the macrocycle π-conjugated system. The role of the electronic substitution effects in the macrocycle deprotonation and metal ion chelating was found to be dominating whereas the macrocycle nonplanar distortions contribute to the acidity and metal chelation rate of the studied porphyrins in less extent. The contributions of both resonance and inductive electronic substitution effects have been distinguished based on the relationship between the weighted sum of resonance and inductive Hammett constants and the acidity and metal ion chelation rate.

Coordination properties of trimeric porphyrin in acetic acid

Trimeric porphyrin H6TP as well as its binuclear Cu2H2TP and trinuclear Cu3TP copper complexes have been prepared. Kinetic features of H6TP and Cu2H2TP complexes formation with copper(II) acetate in acetic acid as well as dissociation kinetics of Cu2H2TP and Cu3TP in acetic acid medium in the presence of sulfuric acid have been studied.