V. Ya. Shafirovich

Complexing of zinc and eosin porphyrins with viologens in aqueous solutions

Conclusions1.The complexing constants of eosin (ZD=−2) and zinc porphyrins (ZD=+4, −4) with charged viologens (ZA=0 to +4) with different ionic strengths were determined.2.It was shown that ΔG of complexing can be considered the additive sum of the ΔG of a donor-acceptor π interaction which is constant in the dye-viologens series and the ΔG of the electrostatic interaction which changes as a function of the charges of the reactants.

Viologens with charged groups: New redox carriers in reactions of photocatalytic separation of hydrogen from water in homogeneous and vesicular systems

Conclusions1.Four viologens were synthesized and characterized with the data from chemical analysis, PMR spectroscopy, spectrophotometry, and polarography.2.The redox potential of the viologen affects the rate constant of liberation of hydrogen from water on a Pt catalyst.3.In contrast to the methyl viologen radical cation, the radicals of viologens with charged groups do not pass through the wall of the vesicle into the external solution, and hydrogen is liberated from water when a Pt catalyst is incorporated in the vesicles.

Photosensitive electrode with a bilaminar modifying coating made with polyxylideneviologenpolysulfostyrene and the bis-2,2′-dipyridyl-4, 4′-diheptadecyl-2, 2′-dipyridyl ruthenium(II) complex

ConclusionsA proposal was made for a photosensitive electrode with a bilaminar film consisting of PXV-PSS2 and [(C17H35)2Dipy]Ru(Dipy)22+ deposited on a conducting base. Its use in a photoelectrochemical cell permits electron transport from EDTA in one half-cell through the bilaminar film and external circuit to Fe(CN)63− in the other half-cell.

Stabilization of charge separation in a zinc porphyrin-viologen-quinone triad

Rate constants have been determined for electron phototransfer reactions in ethanol solutions of the following associated (bonded) systems: zinc porphyrin-viologen, and zinc porphyrin-viologen-quinone. In the case of the zinc porphyrin-viologen-quinone triad, intramolecular electron transfer results in the appearance of a long-lived ion-radical state with a lifetime of ∿10 msec and a quantum yield of ca. 0.15.

PMR determination of the structure of zinc porphyrin complexes with viologens in aqueous solution

Analysis of variations in the PMR chemical shifts of viologens arising from additions of a water-soluble zinc(II) porphyrin makes it possible to carry out a qualitative determination of the structure of molecular complexes formed between the metalloprophyrin and the viologen. The orientation of the viologen and porphyrin planes in the complexes was found to be parallel with the central C-C bond of the viologen located closest to the metal.

Synthesis of photosensitizer pairs containing Ru(bpy)32+ and an electron acceptor (viologen) linked by a hydrocarbon chain

ConclusionsTwo Ru(bpy)32+-viologen complexes, in which the components are linked by a hydrocarbon chain, were synthesized and characterized by PMR, visible, and UV spectrophotometry.

Role of steric and thermodynamic factors in the quenching of the luminescence of ruthenium trisdipyridyl complexes by aromatic electron donors and acceptors

ConclusionsAn increase in the length of the chain of aliphatic substituents in the ligands of ruthenium trisdipyridyl complexes is accompanied by a slight decrease in the rate quenching for the quenching of the luminescence of the complex by aromatic electron donors and acceptors due to steric effects.

Electron phototransfer through the membranes of lipid vesicles containing an osmium trisdipyridyl complex

Conclusions1.Measurements were carried out for the rates of the individual steps of electron phototransfer in a vesicular system with Os(bpy)32+ in the inner layer, (bpy)2Os[bpy(C17)2]2+ in the bilayer, and Ru(bpy)33+ in the external solution. Temperature does not have a significant effect on the rate of electron transfer from (bpy)2Os[bpy(C17)2]2+ localized in the internal monolayer to (bpy)2Os[bpy(C17)2]3+ in the external monolayer.

Effect of a magnetic field on the radical-ion yield upon the quenching of the triplet state of erythrosine by viologens

Conclusions1.The application of an external magnetic field of 1.8 kOe leads to 5–10% decrease in the radical-ion yield in electron transfer from the triplet state of erythrosine to viologens in water.2.The observed effects are explained in the framework of a “triplet” mechanism due to the effect of the magnetic field on relaxational transitions in the system of triplet sublevels of the intermediate triplet exciplex under conditions of highly pronounced anisotropy of the spin-orbital interaction in the heavy atom.

Effect of the nature of the lipid and viologen on transmembrane electron transfer in the vesicular photosystem: electron donor-Ru(bipy) 3 2+ -viologen-oxidant

Conclusions1.The break in the temperature dependence of the transmembrane electron transfer rate constant (in Arrhenius coordinates) corresponds to the phase transition of the lipid from the gel to the liquid crystalline state.2.The transmembrane electron transfer rate constant is not dependent on the structure of the electron carrier, the viologen.