Porphine core saddling: Effects on the HOMO/LUMO gap and the macrocycle bond lengths and bond angles

Abstract

High level ab initio calculations on the saddle distortion of the porphine backbone with dihedral angles in the range 0-30° show the red shift of the Soret and Q bands of the aromatic macrocycle. Also, according to the optimized structure of the planar and saddle shaped porphine, the involvement of in-plane nuclear reorganization in the observed shifts of the bands upon the out-of-plane deformation of the porphyrin core especially to angles larger than 25° cannot be excluded. The distribution of electron density over the porphine frontier orbitals with D2h symmetry has been also studied. © 2012 Elsevier Ltd. All rights reserved.