A. I. V'yugin

Thermochemical characteristics of the near surroundings of tetraphenylporpffln in benzene, pyridine and carbon tetrachloride

Abstract A new approach which allows the solvation surroundings of macrocyclic molecules to be simulated is proposed on the basis of thermogravimetric data. For the first time the compositions are determined of saturated solvates of tetraphenylporphin (H 2 TPP) with benzene, pyridine and carbon tetrachloride: H 2 TPP· 16C 6 H 6 , H 2 TPP· 18C 5 H 5 N and H 2 TPP·16CCl 4 . The energetic parameters of the interparticle interactions in the near solvation surroundings of H 2 TPP are characterized. A method is proposed for the evaluation of the change in enthalpies of solvation of macrocyclic molecules based on the values of the heats of evaporation.

The high sensitive and selective "off-on" fluorescent Zn2+ sensor based on the Bis(2,4,7,8,9-pentamethyldipyrrolylmethene-3-yl)methane.

A fluorescent chemosensor based on the 3,3′-bis(dipyrrin) bearing two chromophoric dipyrrin units was synthesized, which showed a strongly enhanced fluorescent intensity in the presence of Zn2+ ions and a high selectivity toward Zn2+ ions over a wide range of tested metal ions in organic solvents.

Correlation between thermodynamic stability of zinc(II)tetraphenylporphyrine complexes with neutral molecules and physicochemical properties of the coordinated ligands

The heats of interactions of zinc(II)tetraphenylporphyrine with 30 types of neutral molecules in benzene and carbon tetrachloride were measured using the calorimetric titration method. The thermodynamic characteristics of complex formation were calculated. The satisfactory multiparameter correlation of thermodynamic stability of the molecular complexes formed with physicochemical properties of the neutral molecules (electron pair donor ability, volume, electronic and orientational polarization) was obtained.

Titration Calorimetric Investigation of Interactions of Zinc(II), Nickel(II), and Copper(II) Tetraphenylporphine Complexes with Pyridine in Three Solvents

Titration calorimetry was used in a thermodynamic study on the interactions of pyridine (Py) with zinc(II)-tetraphenylporphine (ZnTPP), nickel(II)-tetraphenyl-porphine (NiTPP), and copper(II)-tetraphenylporphine (CuTPP) in benzene, chloroform, and carbon tetrachloride solutions. The coordinating properties of the metalloporphyrins in relation to pyridine were found to diminish in the order ZnTPP > CuTPP > NiTPP. Solvation effects were estimated from the interactions between metalloporphyrins (MP) and Py. The more negative values of the enthalpy and entropy of reaction of ZnTPP with Py, following the order of solvents CCl4 > C6H6 > CHCl3, was found to be related to the different types of (MP–solvent) and (Py–solvent) interactions. The NiTPP and CuTPP complexes showed the opposite trend.

Thermodynamics of Copper(II), Zinc(II), Cobalt(II), Mercury(II), and Nickel(II) Complexation with α,α-Dipyrrolylmethene in DMF

Thermodynamics of complexation reactions between Zn(II), Ni(II), Hg(II), Co(II), and Cu(II) acetates and 3,3′5,5′-tetramethyl-4,4′-dibutyldipyrrolylmethene in DMF at 298.15 K is studied by calorimetric and spectrophotometric methods. The replacement of Zn2+, Ni2+, and Hg2+ ions by Co2+ and Cu2+ ions was found to increase the equilibrium constants of reactions of complex formation with dipyrrolylmethene by more than two orders of magnitude. The role of solvation interactions in coordination of dipyrrolylmethene by d-metal ions is established.

Crystallosolvates of Zn(II)-tetra-tert-butylphthalocyanine with organic ligands: spectroscopic and thermogravimetric studies

Molecular complexes of Zn(II)-tetra-tert-butylphthalocyanine (Zn(tert-Bu)4Pc) with organic ligands (piperidine, morpholine, 1,4-dioxane) were obtained. The stoichiometry, energetic stability and decomposition temperature of the complexes were determined. The effect of specific solvation interactions with the organic solvents on the polymorphic state of Zn(tert-Bu)4Pc was determined.

Titration Calorimetric Investigations on the Interactions of Zn(II) Porphyrin Complexes with Pyridine in Benzene and Chloroform at 298.15 K

Titration calorimetry was used in a thermodynamic study on the interactions of pyridine with natural zinc(II) porphyrin derivatives in benzene and chloroform at 298.15 K. The ability of zinc porphyrins to coordinate to pyridine is higher in benzene than in chloroform and also depends on the molecular structure of the metalloporphyrin.

Crystal solvates of zinc(II) bis(dipyrrinates) with triethylamine: composition, stability and spectral-luminescent properties

Abstract Crystal solvates of 2,2′-, 2,3′- and 3,3′-bis(dipyrrinato)zinc(II) with triethylamine (TEA) were obtained by slow crystallization. Composition, structural organization, stability, and spectral-luminescent properties of the crystal solvates were studied by FTIR, Powder X-ray Diffraction, thermal, mass spectral, absorption and fluorescence analyses. The thermal dissociation processes of crystal solvates in an argon atmosphere have been investigated. It is shown that zinc(II) helicates with decamethylsubstituted 2,2′-, 2,3′-, and 3,3′-bis(dipyrrin)s with TEA form stable supramolecular complexes of the composition [Zn2L2(TEA)4] and [Zn2L2TEA]. Spectroscopic studies showed that the quantum yield (φ) of [Zn2L2(TEA)n] crystal solvates in cyclohexane is noticeably (3–4.5 times) lower than φ of [Zn2L2] complexes. Quantum chemical study indicated the most likely mechanism for the coordination of solvent molecules on the coordinating centers of [Zn2L2]. Thermal and energy stability of [Zn2L2(TEA)n] solvates reduced when replacing the 2,2′- on 2,3′-, and 3,3′-isomer. The obtained results are of interest for the development of [Zn2L2] fluorescent sensors of the electron donor molecules.

Spectral and hydrodynamic studies of complex formation of tetraalkoxy substituted zinc(II)phthalocyanines with defatted and nondefatted bovine serum albumin

Spectral, hydrodynamic and thermochemical studies have been demonstrated that tetraalkoxy substituted zinc(II)phthalocyanines form stable complexes with defatted and nondefatted bovine serum albumin. The phthalocyanines interact with BSA through heteroatoms of their peripheral substitutes. It was found that ZnPc(4-NH-CO-C6H4-OC3H7)4 is located in the protein subdomains IB and IIA whereas ZnPc(4-NHCO-C6H4-OC6H13)4 and ZnPc(4-NH-CO-C6H4-OC8H17)4 are immobilized on surface of the protein globule at a distance of not greater than 10 nm from the tryptophan residues in the positions 135 and 214 of the protein polypeptide chain. Zinc(II)phthalocyanines (ZnPc(4-NH-CO-C6H4-OC6H13)4 and ZnPc(4-NH-CO-C6H4-OC8H17)4) increase thermal stability of BSA.

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.