Fine-Tuning of Luminescence through Changes in Au-S Bond Lengths as a Function of Temperature or Solvent

Inorg Chem. 2019 Jul 1;58(13):8533-8540. doi: 10.1021/acs.inorgchem.9b00845. Epub 2019 Jun 12.

Abstract

The luminescent properties of gold(I)-sulfur compounds have received much attention for their potential applications in the sensing field. The molecular level regulation of luminescence remains a challenge. It is critical to unravel the relationship between the luminescence and the structure. Herein we report a binuclear complex [Au2(dppaptc)2]Cl2 (1, dppaptc = N,N-bis(diphenylphosphanylmethyl)-amino-4-phenyl-thiocarbamide), which exhibits variations at Au-S bond lengths as a function of temperature or solvent. X-ray analysis reveals a linear decrease from 2.900(3) to 2.745(15) Å upon cooling 1·2CHCl3 from 300 to 80 K combined with a linear correlation with its luminescence intensity at 475 nm, which was confirmed by TD-DFT calculations. Compound 1, if solvated with H2O and alcohol, possesses the shorter Au-S bonds and enhanced luminescence. The close relationship between luminescence intensity and Au-S length serves as a complement to existing luminescent gold(I)-sulfur systems and provides some insight into understanding the thermochromism and solvatochromism of the gold(I)-sulfur compounds.