N. V. Chizhova

Bromination of Tetraazaporphine and Its β-Substituted Derivatives Using Pyridine as Solvent and Catalyst

The selectivity and degree of bromination of pyrrole rings in porphyrazine strongly depends on the brominating agent and solvent nature. The reaction of porphyrazine magnesium complex with molecular bromine and N-bromosuccinimide in pyridine gave magnesium complex of dibromotetraazaporphine. Increasing bromine substitution in porphyrazine enhances its acidic properties.

Reactions of Chelate Complexes with Macrocyclic Ligands. Octaphenyltetraazaporphine and Its Derivatives

Coordination of three azaporphines, namely, octaphenyltetraazaporphine (I), octa(4-nitrophenyl)-tetraazaporphine (II), and octa(4-bromophenyl)-tetraazaporphine (III) with some chelate salts of copper and zinc (hydroxyquinolate (IV), α-nitroso-β-naphtholate (V), glycinate (VI), alaninate (VII), valinate (VIII), leucinate (IX), and glutaminate (X)) in DMSO were studied. As in the case with acetates, compound I was found to coordinate chelate salts according to the monomolecular mechanism and to give amino complex with the bridging nitrogen atom. Compound II reacts with all indicated salts according to the bimolecular mechanism almost instantaneously, except for VII. In the same way, reactions of III are also instantaneous, even with VII. Coordination of I with Zn(II) chelate salts proceeds at the rates higher than with acetate.

Kinetics of acid-base interaction of octaphenyl-substituted tetraazaporphyrins with nitrogen-containing bases in a system benzene-dimethylsulfoxide

Effect of dimethylsulfoxide additives on the kinetics of acid-base interaction of octaphenyl-substituted tetraazaporphyrins with nitrogen-containing bases in benzene is studied. A strong effect of the solvent on the process rate and activation parameters is revealed. The relation of the molecular structure of the interacting molecules to their reactivity is demonstrated.

Synthesis and properties of the molecular complex formed by tetrabromotetraazaporphyrin with bromine

Magnesium complex of tetraazaporphyrin reacted with bromine in glacial acetic acid to give a 1:2 molecular adduct of tetrabromotetraazaporphyrin with bromine. The stability of the adduct in media of different polarities was studied. Zinc complex of tetrabromotetraazaporphyrin was synthesized by reaction of the molecular adduct with zinc acetate in dimethylformamide at 20°C.

Study of acidic and complexing properties of tetraphenylporphyrazine and octa(4-bromophenyl)porphyrazine in DMSO at 298 K

The acid dissociation of tetraphenylporphyrazine (H2PA(Ph)4) and octa(4-bromophenyl)porphyrazine (H2PA(4-BrPh)8) and their reactions with Cd2+ ions were studied in DMSO at 298 K. The equilibrium formation constants of the complexes and the acid dissociation constants of porphyrins were calculated; their relationship with the stability constants of the complexes was analyzed. The acidity sequence for porphyrazine derivatives was established.

Solubility of Nitro and Bromo Derivatives of Octaphenyltetraazaporphine

The equilibrium solubility in benzene, tetrachloromethane, and ethyl acetate of octaphenyltetraazaporphine containing electron-acceptor (NO2) and electron-donor (Br) substituents in the phenyl rings was determined. In these solvents, p-substitution in aromatic rings with bromine considerably (by an order of magnitude and more) increases the solubility of porphyrins, whereas p-substitution with the NO2 group does not noticeably affect the solubility of the macrocycle in nonpolar solvents but increases the solubility in ethyl acetate by a factor of more than 200.

Spectropotentiometric Study of Complexation Equilibrium in the System H2TAPBr4, H2TAPCl4-(CH3COO)2Cd-HClO4-DMSO at 298 K

A procedure was suggested for direct measurement of the equilibrium constant of complex formation of porphyrins MX2 + H2P ⇄ MP + 2HX, based on providing conditions under which the direct reaction is suppressed and the reverse reaction is facilitated. The procedure is applicable to complexation of Cd2+ with tetrachloro- and tetrabromotetraazaporphyrins in DMSO in the presence of HClO4.