Thermochemically Stable Liquid-Crystalline Gold(I) Complexes Showing Enhanced Room Temperature Phosphorescence

Abstract

Gold(I) complexes are some of the most attractive materials for generating aggregation-induced emission (AIE), enabling the realization of novel light-emitting applications such as chemo-sensors, bio-sensors, cell imaging, and organic light-emitting diodes (OLEDs). In this study, we propose a rational design of luminescent gold complexes to achieve both high thermochemical stability and intense room temperature phosphorescence, which are desirable features in practical luminescent applications. Here, a series of gold(I) complexes with ligands of N-heterocyclic carbene (NHC) derivatives and/or acetylide were synthesized. Detailed characterization revealed that the incorporation of NHC ligands could increase the molecular thermochemical stability, as the decomposition temperature was increased to ~300 °C. We demonstrate that incorporation of both NHC and acetylide ligands enables us to generate gold(I) complexes exhibiting both high thermochemical stability and high room-temperature phosphorescence quantum yield (>40%) under ambient conditions. Furthermore, we modified the length of alkoxy chains at ligands, and succeeded in synthesizing a liquid crystalline gold(I) complex while maintaining the relatively high thermochemical stability and quantum yield.