Electron‐donor‐acceptor Orbital Correlations‐vii. Intermolecular Orbital (Lcmo) Description of Photosensitized Charge Separation in a 4‐center Unit*

Abstract

Abstract— The conditions under which electronically‐excited 1: 1 complexes are expected to produce high yields of separated radical‐ions are presented with reference to the porphyrin‐quinonc system in terms of the symmetry properties of intermolecular orbitals (IMO). These conditions are translated into design properties of a 4‐center photoinduced charge separation unit DDAO in which post‐excitation energy and electron transfer processes result from diabatic internal conversions between singly‐excited configurations differentiated by the location of holes and electrons in valence and conduction IMO of the unit. It is suggested that a major role of the donor pair is the inhibition of diabatic charge recombination by the low intermolecular component of the vibrational overlap integral over isoenergetic ground (DD) and cationic (DD +) configurations.