Reversible stimuli-responsive luminescence of bimetallic cuprous complexes based on NH-deprotonated 3-(2′-pyridyl)pyrazole

Abstract

Color regulation of solid-state luminescence is desirable and challenging. Herein, we report two new three- and four-coordinate bimetallic cuprous complexes 1 and 2, which bear a NH-deprotonated 3-(2′-pyridyl)pyrazole adopting the monoanionic tridentate μ-η¹(N)η²(N,N) bonding mode and exhibit reversible stimuli-responsive luminescence. It is revealed that the reversible stimuli-responsive luminescence for 1 and 2 is triggered by the destruction and restoration of orderly molecular stacking, along with the loss and recovery of the CH₂Cl₂ solvent molecules for 1. Virtually, this reversible stimuli-responsive luminescence originates from the breaking and rebuilding of various CH⋯O hydrogen bonds around ClO₄⁻, as supported by X-ray single-crystal analysis, the ¹H NMR spectra, and the PXRD and FT-IR spectra in various forms. In addition, the possible applications of this reversible stimuli-responsive luminescence have also been investigated.