Phosphorescence study of matrix effect on Pd-porphin macrocycle conformation

Abstract

In this paper we report the spectral manifestation of existence two spectral forms of Pd-porphin in wide set of Shpol'skii matrices at cryogenic temperatures. The short-wavelength spectral form is attributed to the structure, where the central Pd(II) ion is in plane of the porphyrin macrocycle, while the long-wavelength form is associated with the nonplanar saddle-type conformation of the PdP. The frequencies of the normal vibrations in the ground electronic state have been measured separately for both forms and the differences in the normal modes of two macrocycle conformations are discussed. The type of molecule distortion has been established with using information about the frequencies of vibronic modes from high-resolved spectra of metalloporphins. Matrix effect was shown to have significant role in the stabilization of each of two conformations.