Long-persistence luminescent zinc coordination polymer with multi-stimulus responsiveness: construction, triple-mode...

Polymer-based long-afterglow materials have garnered extensive research attention for information encryption and dynamic anti-counterfeiting applications; however, developing multi-stimulus-responsive and time-resolved long-afterglow materials remains challenging. Herein, a novel zinc(II) coordination polymer (CP) {[Zn₄(ATA)₂(BTC)₂(H₂O)₃]}_n (1) based on trimesic acid (H₃BTC) and 5-amino-1,2,4-triazole (ATA) was synthesized via a one-pot method. Complex 1 exhibits trimodal luminescence i.e., fluorescence, delayed fluorescence (DF), and room temperature phosphorescence (RTP), along with reversible NH₃ vapor chromic properties and excitation-wavelength-dependent emission attributed to the coexistence of local excitation (LE) and ligand-to-ligand charge transfer (LLCT) with multiple emission centers in its electronic structure. Complex 1 shows an intense phosphorescence peak at 553 nm (τ = 0.514 s) and a weak DF peak at 416 nm (τ = 9.027 μs). Deconvolution of the phosphorescence emission of complex 1 gave three peaks at 414 nm, 550 nm, and 557 nm, corresponding to DF, green afterglow, and yellow afterglow, respectively. Its superior long afterglow performance benefits from the synergistic effect of its favorable coordination geometry and dense hydrogen bond networks that suppress non-radiative transitions and are conducive to the formation of a triplet exciton. With its multi-stimulus-response and time-resolved afterglow properties, complex 1 has great potential in multi-level encryption and anti-counterfeiting applications.