Solvent-Responsive Afterglow Switching in a Coordination Polymer and Its Application for DMSO Detection

Molecular-based afterglow materials─particularly porous coordination polymers (CPs)─are highly attractive for their tunable host-guest chemistry, but achieving reversible afterglow switching in suspensions remains challenging due to quenching by molecular collisions and oxygen. Herein, we report a two-dimensional bilayer porous CP (1) that exhibits only short-lived room temperature phosphorescence (378.1 μs). Specifically, this emission can be activated by dimethyl sulfoxide (DMSO), yielding a green afterglow with a lifetime of 102.1 ms. This distinct response prompted us to systematically investigate the luminescence of 1 in a series of "DMSO + X" mixed-solvent suspensions, and three classes of switching behavior were identified: (i) abrupt threshold-like switching in DMSO + ethyl acetate and DMSO + N,N dimethylformamide systems, enabling DMSO afterglow detection in ethyl acetate with a low limit of 0.39% (v/v); (ii) a gradual emission transition in systems containing N,N-dimethylacetamide, N,N-diethylformamide, or acetonitrile; and (iii) a multistage leap with tunable emission in the presence of methanol or ethanol. Mechanistic studies reveal the afterglow turn-on triggered by DMSO arises jointly from enhanced structural rigidity and increased frontier-orbital delocalization. This work establishes CPs as versatile platforms for studying solvent-regulated afterglow and demonstrates their promise in advanced chemical sensing.