IRREGULAR BEHAVIOR OF 5,10,15,20-TETRAKIS(PENTAFLUOROPHENYL)PORPHYRININ LANGMUIR-BLODGETT-FILMS

Multilayer Langmuir-Blodgett films containing 5,10,15,20-tetrakis(pent afluorophenyl)porphyrin (PFP) in octadecylamine and in fatty acid matr ices were prepared. The films revealed relatively long fluorescence li fetimes with an irregular concentration dependence: the longer lifetim e corresponded to the higher concentration of PFP. Fluorescence decay- associated spectra indicated that energy migration contributed to the relaxation of the singlet excited state at all concentrations studied. In comparison with solutions, the absorption spectra of the films rev ealed a distinct band narrowing and an increase in molar extinction of the Soret band. Presumably, PFP formed unusually uniform structures, a kind of highly ordered aggregates, in the plane of monolayers. (C) 1 998 Elsevier Science B.V. All rights reserved.