N. Sh. Lebedeva

New basicity/nucleophilicity scale on the basis of parameters of formation of axial n,ν-complexes derived from tetraphenylporphyrinatozinc(II) and base/nucleophile as ligand

The stability constants of complexes derived from tetraphenylporphyrinatozinc(II) and various ligands in chloroform at 25°C were proposed as nucleophilicity/basicity parameters of the latter, which reflect the effects of electronic and steric factors. Supernucleophilicity of heteroaromatic N-oxides in reactions with electrophiles was interpreted in terms of sp2–sp3 rehybridization of the N-oxide oxygen atom.

Stability of benzotriazolyl-substituted phthalocyanines with respect to thermal oxidative decomposition

The thermal oxidative decomposition of benzotriazolyl-substituted phthalocyanines and their copper complexes is investigated by means of thermogravimetric, elemental, and spectroscopic analysis. It is shown that the nature of peripheral substituents exerts the greatest effect on the thermal stability of the compounds.

Thermodynamics of Complexation of Sucrose with 18-Crown-6 in Water

The formation of the 1 : 1 sucrose complex with 18-crown-6 in an aqueous solution was established using the calorimetric titration and density measurement methods. It is an entropy stabilized complex.

Kinetics of thermal oxidative decomposition of zinc porphyrin and phthalocyanine complexes

Thermal oxidative decomposition of certain zinc porphyrin and phthalocyanine complexes was studied using an installation for thermal analysis, and kinetic parameters of the thermal oxidation of these compounds were determined. The introduction of peripheral alkyl substituents into porphyrin molecules enhances the macroring stability with respect to the thermal oxidation. In cases of benzoporphyrins and phthalocyanines, this effect is leveled off because of spatial remoteness of the substituent from the reactive center of the macroring. The substances studied decompose in several steps; the initial step corresponds to the oxidation of peripheral substituents of the macroring. For the majority of the substances studied, the order of the thermal oxidation reaction is 1, and the main step controlling the thermal oxidation process is diffusion.

Molecular Porphyrin and Metalloporphyrin Complexes

The formation of specific molecular complexes of synthetic and natural porphyrins and metalloporphyrins with molecular ligands of different nature is considered. Data on composition, energy and thermal stability of donor–acceptor and π–π-complexes of porphyrins and metalloporphyrins were obtained by thermogravimetric analysis of crystal solvates.

Association of Zn(II)tetra-4-carboxyphthalocyanine in aqueous solutions

Association of Zn(II)tetra-4-carboxyphthalocyanine in aqueous solutions is studied. The influence of the permittivity of the solvent and pH of the medium and the effects of adding ethanol, electrolytes, electron donor materials, and π-π complexing agents on the state of Zn(II)tetra-4-carboxyphthalocyanine in a solution are revealed.

Thermooxidative Decomposition of Heterocyclic N-Oxides

Thermooxidative decomposition of pyridine N-oxide, 4-(4-dimethylaminostyryl)pyridine N-oxide, 4-(4-methoxystyryl)pyridine N-oxide, quinoline N-oxide, 2-methylquinoline N-oxide, 4-chloroquinoline N-oxide, 2-styrylquinoline N-oxide, and 2-(4-dimethylaminostyryl)quinoline N-oxide was studied. The kinetic parameters of the thermooxidative processes were calculated according to three independent procedures. The relation between the nature of heterocyclic N-oxide and its stability to thermal oxidation was analyzed.

Interaction peculiarities of 5,10,15,20-tetrakis(4-N-methylpyridil) tetra iodide porphyrin with albumin

In present work interactions of bovine serum albumin with 5,10,15,20-tetrakis(4-N-methylpyridil) tetra iodide porphyrin have been studied by electron absorption and fluorescence spectroscopy. The studies were carried out in aqueous media at different pH and in water-dimethylformamide mixtures containing up to 0.19 M of the organic solvent. It has been demonstrated that the porphyrin forms stable complexes with BSA in which the porphyrin is located subdomains IB and IIA. The stability constants of the complexes is practically independent of pH.

Polymorphism and molecular metal phthalocyanine complexes

Generalized data and new results characterizing the molecular metal phthalocyanine complexes with electron-donor and π-π-complexing agents are presented. It is shown that the crystalline packing of pseudopolymorphs formed by molecular complexes of metal phthalocyanine: ligand = 1: 2 is similar to the packing of molecules of metal phthalocyanine in the β-polymorphic form, while the molecular complex (1: 1) shows similarity to the α-polymorph. The topography of films based on axial and π-π complexes Zn(tert-Bu)4Pc is evaluated. It is shown that the surface of films based on biligand complexes is generally smooth, flat, and dense, although there are some rather large crystallites. The topography of the films is not regular, because the π-stacking axis of the pseudopolymorphs of β-crystallites is situated perpendicularly to the substrate. Films obtained on the basis of monoligand complexes are layered; the layers are perpendicular to the substrate, and the topography of the film is regular, because the π-stacking axis of the pseudopolymorphs of α-crystallites is parallel to the quartz substrate. An alternative way to obtain metal phthalocyanines of a given polymorphic modification is discussed.

Thermal behavior of quinoline N-oxide hydrates and deuterohydrate

Spectral and thermochemical investigation of physicochemical properties of quinoline N-oxide crystallohydrates with H2O and D2O is carried out. Quinoline N-oxide is established to form with H2O a stable dihydrate where two water molecules are energetically not equal. Complete dehydration of quinoline N-oxide occurs when temperature reaches 150°C. With accounting for the obtained thermochenical data, quinoline N-oxide and its mono- and dihydrates are isolated in the individual state and their IR spectra are registered and considered. It is established that at boiling quinoline N-oxide in D2O proceeds chemical reaction affording isoindoline-1,3-dione (phthalimide). The product is identified by elemental analysis and 1H NMR and IR spectroscopy. The band assignment in the IR spectra of quinoline N-oxide, phthalimide and of the complex of the latter with D2O is based on the quantum-chemical DFT calculations.