Photoinduced energy transfer in sulfur-based heterocyclic compounds and corrole dyads

Abstract

We have designed and synthesized three donor-acceptor systems in which corrole macrocycle is an energy acceptor and sulfur-based heterocyclic compounds such as thianthrene (S1-Cor), dibenzothiophene (S2-Cor) and benzothiophene (S3-Cor) are the donors at its meso phenyl position. The molecular integrity of all three D-A systems has been characterized by various spectroscopic techniques that include elemental analysis, 1H NMR and MALDI-MS. Differential functional theory studies suggest that the electron density of the highest occupied molecular orbital (HOMO) spread on both corrole and sulfur-substituted heterocyclic units whereas the lowest occupied molecular orbital (LUMO) spreads on corrole macrocycle only. Singlet excited state properties indicate that there is an efficient intramolecular photoinduced energy transfer (PEnT) from donor heterocyclic unit to corrole, when excited at [Formula: see text]290 nm. Förster theory was adopted to explain the PEnT reaction in these dyads. The time-correlated singlet photon counting (TCSPC) studies suggest that energy transfer rates ([Formula: see text] are found to be in the range of 1.06 × 109 S[Formula: see text] to 6.67 × 109 S[Formula: see text] and are solvent-dependent.