Stimuli-Responsive Luminescent Properties of Dinuclear Cu(I) Complexes Regulated by Hydrogen-Bonding Donors

The selection of hydrogen-bonding donors is crucial for the development of stimuli-responsive luminescent materials that rely on weak hydrogen-bonding interactions. In this study, we report two novel dinuclear Cu(I) complexes, [Cu₂(μ-η²(N,N),η²(N,N)-dpa)(μ-dppm)₂](ClO₄) (1) and [Cu₂(μ-η²(N,N),η²(N,N)-dpa)(μ-dppa)₂](ClO₄)·2CH₃COCH₃ (2), which differ in their diphosphine linkers (CH₂ in dppm vs NH in dppa). X-ray crystallography reveals weak CH···O hydrogen bonds between dppm-CH₂ and perchlorate-O in 1 and weak NH···O interactions between dppa-NH and acetone-O in 2. The destruction of CH···OClO₃^- hydrogen bonds in 1, induced by grinding, triggers mechanochromic luminescence. In 2, the disruption of NH···OC(CH₃)₂ hydrogen bonds, caused by heating and grinding, leads to both thermochromic and mechanochromic luminescence. It is demonstrated that differences in donor-acceptor pairing (CH₂/ClO₄^- vs NH/acetone) influence the nature and responsiveness of hydrogen-bonding interactions. Furthermore, these results offer new insights into the design and synthesis of low-cost, multistimuli-responsive luminescent materials through the modification of hydrogen-bonding donors.