Structure and emission properties of dinuclear copper(i) complexes with pyridyltriazole

A new series of five highly emissive binuclear heteroleptic pyridyltriazole-Cu(i)-phosphine complexes 1-5 was synthesized and examined by different experimental (IR, elemental and thermogravimetric analysis, single crystal X-ray diffraction technique, UV-vis and fluorescence spectroscopy) and quantum chemical aproaches. Complexes 1-5 exhibited excellent stimuli-responsive photoluminescent performance in the solid state at room temperature (quantum yield (QY) = 27.5-52.0%; lifetime (tau) = 8.3-10.7 mu s) and when the temperature was lowered to 77 K (QY = 38.3-88.2; tau = 17.8-134.7 mu s). The highest QY was examined for complex 3 (52%) that can be explained by the small structural changes between the ground S-0 and exited S-1 and T-1 states leading to the small S-1-T-1 triplet gap and efficient thermally-activated delayed fluorescence. Moreover, complex 4 demonstrates reversible mechanochromic and excitation dependent luminescence.