Photo-induced electron transfer in covalently linked donor–acceptor assemblies in liquid crystals. Time-resolved electron paramagnetic resonance

Abstract

Intramolecular electron transfer (ET) in cis and trans isomers of a covalently linked porphyrin–cyclohexylene–quinone, oriented in liquid crystals (LCs), is monitored by time‐domain electron paramagnetic resonance (EPR) spectroscopy over an extended range of temperature, i.e., 210<TTL. The different spectra of the two isomers are interpreted in terms of their different molecular geometry. In the case of the trans isomer, both triplet‐ and probably singlet‐initiated ET routes can concurrently be detected, and the free energy of the charge‐separated state is estimated from the spectral dynamics.