Synthesis, Photophysical\nand Electrochemical Properties\nof Spiro-Phosphonium Compounds

Abstract

A series of spiro-phosphonium compounds have been synthesized\nby\ncopper-mediated coupling reaction of phosphacyclic compounds with\nalkynes. Their photophysical properties are tuned by varying substituents\nand exhibit different luminescent colors from blue to green, and finally,\nyellow. The fluorescence quantum efficiency of diethyl spiro-xanthenebenzophosphole <b>3aa</b> in solid and liquid states reached 31% and 76%, respectively.\nDiphenyl spiro-xanthenebenzophosphole <b>3ad</b> displayed relatively\nlow cytotoxicity toward lung cancer cells A549 and was able to effectively\npenetrate the cell membrane and maintain strong staining. Moreover,\ndensity functional theory (DFT) and time-dependent DFT calculations\nhave been performed to explore the origin of their photophysical properties.