CHARACTERISTICS OF DONOR-ACCEPTOR COMPLEXES FORMED IN PORPHYRIN-POLYMER SYSTEMS AND THEIR PHOTOACTIVATION IN ELECTRON-TRANSFER PHOTOREACTION

Donor-acceptor complexes formed between meso-tetra(p-aminophenyl)porph ine moieties covalently bound to polymers (e.g. poly(methacrylic acid) (PMA) and the influence of substances with electron-accepting affinit ies (molecular bromine, hydrogen ions and benzylviologen) on the prope rties of these complexes were investigated using fluorescence and abso rption spectroscopy. Electron transfer to the viologen in a system inc luding a sacrificial electron donor (triethylamine) with accumulation of reduced benzylviologen under steady-state illumination was also stu died. A correlation between IR emission assigned to charge transfer co mplex fluorescence and efficiency of electron transfer to the viologen has been revealed. The IR emission is the most intense in porphyrin c ovalently bound to PMA compared with other polymers. Differential abso rption spectra of associated meso-tetra(p-aminophenyl) porphine bound to macromolecules indicate the involvement of macromolecule carboxyl g roups in the structure of the donor-acceptor complex. Incorporation of molecular bromine or hydrogen ions in this structure due to non-valen t interactions leads to a considerable change in the absorption spectr um of the complex. In the case of benzylviologen incorporation, its in volvement in the complex structure occurs during the photoinduced elec tron transfer to benzylviologen in the system including the sacrificia l electron donor. The appearance of unusual features in the latter sys tem is interpreted as the photoactivation of the donor-acceptor comple x.