Vitrification and Cold Crystallization of a One-Dimensional Perovskite-like Compound Enabled by Reorganizable Coordination Bonds and a Configurationally Restricted Cation.

Understanding glass formation and transformation remains a fundamental challenge in materials science. Here, we report the first example of vitrification and multifactor-triggered cold crystallization in a one-dimensional (1D) perovskite-like coordination polymer, (4-methylmorpholinium)[Cd(SCN)₃]. By introducing cleavable and reorganizable Cd-S/N coordination bonds, we enable glass formation via melt-quenching, a process previously unachievable in 1D perovskite-like compounds. Comprehensive structural and spectroscopic analyses as well as molecular dynamics simulations, especially in-depth solid-state NMR analysis, reveal that reversible coordination bond reorganization and the restricted configurational freedom of the methylmorpholinium cation drive the glass-crystal transition. Combined dynamic and isothermal DSC studies demonstrate that cold crystallization proceeds via instantaneous nucleation and 1D crystal growth, driven by the confined rearrangement of the 4-methylmorpholinium cation. These findings establish a new vitrification mechanism based on dynamic coordination bonds, providing molecular-level insight into phase transitions in low-dimensional hybrid organic-inorganic perovskites or perovskite-like compounds and offering new strategies for glass-forming hybrid materials.