Films of polyvinylpyrrolidone containing zinc tetraphenylporphyrin: evidence for aggregation of porphyrins in the presence of pyridine

Abstract Films of zinc porphyrins in polyvinylpyrrolidone have been formed and studied by spectrophotometric methods. Diffusion of gaseous pyridine through a film of polyvinylpyrrolidone containing zinc tetraphenylporphyrin 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 epifluorescence, using a Titane-Sapphire laser as the excitation source. Fluorescence is collected through an optical fiber. The technique allows for the study of well-defined zones in the film.