Luminescence Switching of a Gold–Copper Supramolecular Complex: A Physical Insight

Abstract

Stimuli-responsive metal complexes are extensively studied due to their promising properties for various practical applications. In many cases, stimuli-induced response is provoked by phase transitions, which completely modify electronic properties of chromophoric center to give substantial modification of the phase emissive properties. However, complexity of the systems hinders theoretical calculations, which could be used to interpret the emission response, even at qualitative level. In this study, we apply a joint experimental and theoretical approach to model the luminescence switching of a vapochromic Au–Cu organometallic supramolecular complex in solution, amorphous, and crystal state. We have investigated luminescence spectra and emission anisotropy of the complex in solution, polymer gel, amorphous, and crystal states. The excitation and emission energies of the complex in vacuum and crystal state have been calculated using QM and QM/MM approaches. The results show that (1) the red shift of emission of the complex in solution is caused by the conformational relaxation in the T1 state and (2) the blue shift of crystalline state emission originates from the interactions of the complex with the crystal environment. The model elaborated to describe the phenomena observed may provide a practical way to analyze stimuli-induced luminescence switching in analogous systems.