A tricolor-switchable stimuli-responsive luminescent binuclear Cu(i) complex with switchable NH⋯O interactions

Abstract

Color regulation of solid-state luminescence is desirable and challenging. We report herein a new 1,2,4-triazole-based bimetallic cuprous complex exhibiting blue-green-yellow tricolor luminescence conversion and thermally activated delayed fluorescence, and the origin and possible application of this tricolor luminescence conversion are also studied. It is shown that blue-green bicolor luminescence conversion is ascribed to the loss and recovery of CH₂Cl₂ solvent molecules, as supported by the CH₂Cl₂-filled pore channel structure present in the crystal lattice revealed by single-crystal structural analysis and the variation of CH₂Cl₂ signal in the ¹H NMR spectra. Green-yellow bicolor luminescence conversion is attributed to the destruction and restoration of the packing mode caused by the breaking and rebuilding of NH⋯O hydrogen bonds under grinding and CH₂Cl₂ vapor, as confirmed by PXRD and FT-IR analyses in various solid states.