Dithienylethene-bridged gold(I) isocyanide complexes: Synthesis, photochromism and “turn-on” fluorescent switching behavior

Abstract

Developing novel photochromic complexes based on dithienylethene is highly desirable for potential application in the fields of photoresponsive optoelectronics. In this contribution, four novel dithienylethene-bridged gold(I) isocyanide complexes 1a-1d have been designed and prepared by appending alkynyl-gold(I)-isocyanide triads at the termini of dithienylethene unit. They were fully characterized and confirmed by 1H NMR, 13C NMR, and HRMS (MALDI). Moreover, investigation on photochromic properties indicated that these complexes had good photochromic behavior upon irradiation with UV (302 nm) and green light (530 nm). And the effect of terminal ligands on photochromic properties of these gold(I) complexes was observed. Surprisingly, they displayed an unusual “turn-on” fluorescent switching behavior upon irradiation with UV light, which was mainly attributed to LMCT (ligand-to-metal charge transfer) for ring-closed isomers of these complexes by TD-DFT calculations. Accordingly, these complexes can be utilized as a potential fluorescent switch in smart optoelectronic materials.