Excitation-Dependent Luminescent Properties with Wide Range of Color Changes Using a Liquescent Cationic Gold(I) Complex

Abstract

The solid form of a bis(trifluoromethanesulfonyl)imide ion salt of a cationic gold(I) complex ligated with cyclohexylisocyanide and an N-heterocyclic carbene is found to exhibit excitation-dependent luminescent properties. The solid form, prepared by maintaining the liquid phase of the complex at 90 °C for 7 days followed by cooling to 25 °C, displays bluish-purple, purple, orange, and red emissions under excitations at 340, 360, 370, and 380 nm, respectively. Excitation-dependent emission spectra reveal that the observed color changes result from varying intensity ratios of two emission bands centered at 430 and 652 nm. Control experiments suggest that these excitation-dependent luminescent properties originate from the coexistence of gold(I)–π aggregates and gold(I)–gold(I)-interacted oligomers, which exhibit higher and lower bandgap energies, respectively.