Photoinduced intramolecular reactions in triphenylamine-corrole dyads

Donor-Acceptor systems, in which a donor triphenylamine (TPA) directly connected to a corrole (Cor) acceptor (TPA-Cor) and separated by an ethynylphenyl bridge between TPA and Cor (TPA-E-Cor) have been designed, synthesized and fully characterized by elemental analysis, MALDI-MS, UV-Visible and H-1 NMR spectroscopic methods. A comparison of the UV-Visible and H-1 NMR features of these D-A systems with those of the corresponding individual model compounds (i.e., TPA and Cor) reveal that there exist minimum pi-pi interactions between triphenylamine and corrole pi-planes. Quenched emission of triphenylamine (but not corrole) part of both the dyads have been observed in three different solvents. Excitation spectral data provides evidence for an intramolecular excitation energy transfer (EET) from the singlet triphenylamine to the corrole. Detailed analysis of the data suggests that Forster's dipole-dipole mechanism does not adequately explain this energy transfer but, an electron exchange mediated mechanism can, in principle, contribute to the intramolecular EET. (C) 2014 Elsevier B.V. All rights reserved.