Fluorescent coordination-polymer single crystals with tunable elastic–plastic transformations

Abstract

Achieving and controlling mechanical responses in single crystals with complex coordination architectures remains challenging. Here, we report the design and synthesis of a homologous series of one-dimensional cadmium(II) coordination polymers that exhibit controllable bending under an external load. Systematic modification of imidazole-based ligands modulates the periodic Cd⋯Cd separation along the chains, thereby tuning the macroscopic response from elastic to plastic. Based on experimental results and data analysis, we identified an inverse correlation between the metal–metal repeat distance and the attainable elastic strain, consistent with a molecular-spring-like Cd–Cl–Cd backbone. In parallel, the imidazole chromophores endow all materials with stable blue photoluminescence under 365 nm excitation. The convergence of mechanical adaptability and intrinsic emission identifies these crystals as promising candidates for flexible optoelectronic components and optical waveguides.