FILMS OF POLYVINYLPYRROLIDONE CONTAINING ZINC TETRAPHENYLPORPHYRIN - EVIDENCE FOR AGGREGATION OF PORPHYRINS IN THE PRESENCE OF PYRIDINE

Films of zinc porphyrins in polyvinylpyrrolidone have been formed and studied by spectrophotometric methods. Diffusion of gaseous pyridine t hrough a film of polyvinylpyrrolidone containing zinc tetraphenylporph yrin leads to a rearrangement of the porphyrin dye with the formation of aggregates. Absorption and fluorescence spectra are complemented by observations under an inverted Nikkon microscope equipped for epifluo rescence, using st Titane-Sapphire Laser as the excitation source. Flu orescence is collected through an optical fiber. The technique allows for the study of well-defined zones in the film. (C) 1997 Elsevier Sci ence S.A.