Synthesis and Photophysics of Phenylene Based Triplet Donor–Acceptor Dyads: ortho vs. para Positional Effect on Intramolecular Triplet Energy Transfer

Abstract

ABSTRACT: Two phenylene based geometrical/isomeric triplet ortho- and para–dyads (o–3 and p–3, respectively) were synthesized and fully characterized using advanced photophysical tools and computations. In dyad o–3, the through-space donor-acceptor interactions led to simultaneous triplet energy transfer and charge transfer with identical kinetics. On the other hand, in the dyad p–3, it was found that the phenylene spacer favors a fast triplet energy delocalization over the charge transfer process. Furthermore, analysis of the results from the present investigation indicates that the deactivation of the photo-excited species (o–3)* occurs through both the intrinsic channel viz. S0←S1 and charge recombination. In the case of dyad p–3, the results indicate that the primary deactivation pathway is self-quenching or triplet-triplet annihilation involving the acceptor unit(s).

Keywords

• Triplet photochemistry
• Triplet energy transfer
• bichromophores
• Charge transfer
• Triplet-triplet annihilation