Methoxy-Substituted Difluoroboron Benzoylacetonate Complexes with Color-Tunable Phosphorescence

Difluoroboron beta-diketonates (BF(2)bdks) exhibit fluorescence (F) and room-temperature phosphorescence (RTP) in a poly(lactic acid) (PLA) matrix. Fluorescence color tuning has been achieved by dye loading or bdk ligand modification, namely substituent effects or extended conjugation. In this study, color-tunable RTP (450-570 nm) is achieved with 1-benzoylacetonate derivatives by varying the number and position of methoxy groups on the benzene ring. The methoxy groups can be used to alter the energy levels of the dye or induce geometry changes (e. g. twisting) to disrupt pi-conjugation. The dyes were evaluated theoretically with density functional theory (DFT) and spectroscopy (absorbance and fluorescence) in CH2Cl2 solution and dilute PLA blends. These findings inform future boron-based lighting devices and oxygen-sensing bioprobe designs.