Chiral Ligand Engineering Enables High-Contrast Stimuli-Responsive Luminescence and Circularly Polarized Luminescence in Enantiomeric Dinuclear Cu(I) Complexes

Developing chiral luminescent materials integrating high-contrast stimuli-responsiveness with circularly polarized luminescence (CPL) remains a major challenge. Herein, we report a new pair of enantiomeric dinuclear Cu(I) complexes ((4S,7R)-1 and (4R,7S)-1) constructed from tailored chiral pyridyl-pyrazole ligands. These complexes exhibit not only distinct CPL but also high-contrast, reversible stimuli-responsive luminescence in the solid state. SCXRD, PXRD, FT-IR, and DFT calculations collectively reveal that the emission switching triggered by grinding and CH2Cl2 fuming originates from a reversible crystalline-to-amorphous phase transition, driven by the cleavage and reformation of weak intermolecular interactions, particularly the key pyrazole-N–H···O (perchlorate) hydrogen bonds. Crucially, the emission color contrast is effectively modulated by the enantiopure 1,1,2-trimethylcyclopentane chiral auxiliary moieties (4S,7R and 4R,7S) appended to the ligands, thus underscoring the decisive role of chiral configuration in tuning luminescent properties. This work establishes a versatile chiral ligand engineering strategy and offers valuable insights into the rational design of advanced chiral stimuli-responsive luminescent materials.