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- Title
The Influence of Electronic and Structural Factors on the Photoinduced Electron Transfer in Sterically Strained Meso-Nitrophenyl-Substituted Porphyrins.
- Authors
Avilov, I. V.; Zen'kevich, É. I.; Sagun, E. I.; Shul'ga, A. M.; Filatov, I. V.
- Abstract
The electronic and structural factors affecting the efficiency of the photoinduced electron transfer in meso-nitrophenyl-substituted octaethylporphyrins are theoretically analyzed by semiempirical methods of quantum chemistry. It is shown that the experimental differences between the rate constants of electron transfer associated with the change in the position of the nitro group in the meso-phenyl ring (ortho, meta, or para positions) are determined by such factors as torsional vibrations of the phenyl ring around the single C[sub 1]–C[sub m] bond, electronic properties of the phenyl group, rotations of the nitro group around the single C–N bond, and out-of-plane deformations of the porphyrin macrocycle. It is ascertained that the matrix elements of electronic interactions and the energies of excited charge-transfer states depend substantially both on the position of the nitro group in the meso-phenyl ring and on intramolecular vibrations of the phenyl and the nitro groups. In nonpolar media, the fluorescence quenching in the compounds under study occurs mainly due to the admixture of charge-transfer excitations to the lowest S[sub 1] state of porphyrin. Upon increasing polarity, the main channel of deactivation of excited singlet states is direct photoinduced electron transfer either through space (the ortho position) or through a bond involving the participation of orbitals of the phenyl spacer (the meta and para positions). © 2003 MAIK “Nauka / Interperiodica”.
- Subjects
MOLECULAR spectroscopy; CHARGE exchange; STRUCTURAL design; PHENYL compounds; PORPHYRINS
- Publication
Optics & Spectroscopy, 2003, Vol 95, Issue 5, p696
- ISSN
0030-400X
- Publication type
Article
- DOI
10.1134/1.1628717