Transformations in the fluorescence line narrowing spectra of porphin upon the formation of diprotonated species

Abstract

Fluorescence line narrowing spectra of the diprotonated forms of the porphine have been obtained in solid acid solutions at liquid helium temperature. Quantum-chemical calculations of frequencies and forms of in-plane and out-of-plane vibrations for the diprotonated forms were also performed. The manifestation of intense vibronic transitions in the fineline fluorescence spectra of diprotonated forms of Н2P with participation of out-of-plane modes have been estimated on the basis of mutual analysis of the experimental data and the results of quantum chemical calculations. The reason for the spectral activation of out-of-plane modes consists in saddle distortion of the porphine molecule upon formation of the diprotonated form.