6533b85cfe1ef96bd12bca0c

RESEARCH PRODUCT

Harnessing Fluorescence versus Phosphorescence Ratio via Ancillary Ligand Fine-Tuned MLCT Contribution

subject

description

A series of gold(I) alkynyl-diphosphine complexes (XC6H4C2Au)PPh2—spacer—PPh2(AuC2C6H4X); spacer = —C2(C6H4)nC2— (A1, n = 2, X = CF3; A2, n = 2, X = OMe; A3, n = 3, X = CF3; A4, n = 3, X = OMe), —(C6H4)n— (B5, n = 3, X = OMe; B6, n = 4, X = OMe) were prepared, and their photophysical properties were investigated. The luminescence behavior of the titled compounds is dominated by the diphosphine spacer, which serves as an emitting ππ* chromophore. The complexes exhibit dual emission, comprising low and high energy bands of triplet (phosphorescence) and singlet (fluorescence) origins, respectively. The electron-donating characteristics of ancillary groups X significantly affect the LLCT/MLCT contribution of both alkynyl ligand and the metal center into the lowest lying excited state. In turn, it substantially influences the rate of intersystem crossing kisc S1 → Tm (m ≥ 1) that allows for tuning the ratio fluorescence vs phosphorescence without alteration of the chromophore core. Quantum chemical analysis of...