Optical transition energies of porphyrins

Abstract

Transition energies for porphyrins in the Soret and Q-band spectral regions are calculated by utilizing a modified free electron molecular orbitals (FEMO) method. In this procedure a simple model is being employed where each porphyrin is represented by a two dimensional box whose effective width and length are determined by a suitable linear combination of well defined conjugation routes within the molecular π-system. These routes are determined by considering the inherent properties of the porphyrins as imposed by their molecular structure. The zero-order treatment, where the π-centres are indistinguishable, is further extended by taking into account the difference in electronegativity between the C-centres and hetero centres (N-atoms with various groups attached). Several porphyrins are treated free-base tetraphenylporphyrin, free-base tetraphenylchlorin Zn-tetraphenylporphyrin, Pb-tetraphenylporphyrin and K₂-tetraphenylporphyrin.

Additional information

Notes on contributors

H. Levanon

In partial fulfilment of the requirements for the Ph.D. in the Department of Physical Chemistry, The Hebrew University, Jerusalem.