Harnessing Triplets of TIPS-Anthracene-Based Au(I) Complexes for Photoinduced Electron Transfer and Room-Temperature Phosphorescence

Abstract

Excited triplet states are key to many optoelectronic applications due to their long lifetimes and unique spin properties. Triisopropylsilyl (TIPS)-acene derivatives are well-known for their rich triplet-mediated photochemistry. However, metal-functionalized acenes remain scarce, and the influence of metal coordination on triplet-state processes is largely unexplored. Here, we functionalize a TIPS-anthracene backbone with a diphenylphosphine group and report two gold(I) complexes: monomeric [Au(TIPS-AntP)Cl] and dimeric [Au(TIPS-AntP)2OTf]. The excited-state dynamics of the ligands and the complexes were investigated in solutions. Both Au(I) complexes exhibit nearly quantitative intersystem crossing, efficiently generating triplet excited states. Time-dependent density functional theory (TD-DFT) calculations corroborated the experimental absorption and emission results by providing insights into the energy gaps governing photophysical processes. The role of the Au(I) in triplet formation was investigated using femtosecond and nanosecond transition absorption spectroscopy. Alongside fluorescence emission, both the ligands and their complexes exhibit room-temperature phosphorescence (RTP), with the Au(I) complexes displaying enhanced RTP intensity. The photoactive triplet states of the Au(I) complexes possess sufficiently long lifetimes to enable photoinduced electron transfer to appropriate electron acceptors. Overall, these findings establish Au(I)-coordinated TIPS acenes as a promising platform for triplet-mediated photochemical and optoelectronic applications.