A diamond-like cuprous coordination polymer based on the [Cu8I6]2+ cluster with multistimuli-responsive luminescence and iodine adsorption behavior

Abstract

Copper(I) iodide-based compounds can exhibit interesting multistimuli-responsive behaviors and have attracted great interest due to their widespread applications. In this study, a novel copper(I) complex, formulated as [Cu₈I₆(CN)₂(PPh₃)₄]_n (1) with the [Cu₈I₆]²⁺ cluster as a secondary building unit, is reported. The synthesis, structure, photoluminescence, and the sorption and release of I₂ were investigated in detail. The selection of the non-centrosymmetric bridging ligand CN⁻ and the tetrahedral coordination geometry of Cu(I) result in a diamond-like framework of complex 1 with nonlinear optical properties. Complex 1 exhibits ultralong luminescence with a temperature-dependent afterglow color change, which can be attributed to the modifications and transitions of different energy states. Upon mechanical grinding, 1 also exhibits redshifted emission from cyan-yellow to dark-red due to the transformation from a crystalline state to an amorphous state. In addition, 1 has good adsorption and desorption processes of I₂ due to the weak interaction of I₂ with coordinated I⁻ in the framework.