Highly emissive coordination polymer derived from tetraphenylethylene-tetrazole chromophore: Synthesis, characterization and piezochromic luminescent behavior

Solid-state materials that exhibit pressure stimulus-response characteristics in a manner of emission signal, known as piezochromic luminescence (PCL), demonstrate great potential in photoelectric devices. The weakened luminescence and insignificant color change in the aggregation state, however, hampers their practical applications. Herein, a highly emissive coordination polymer, [Zn2(H4TTPE)(H2O)4]·H2O (CUST-805), is successfully constructed by employing an AIE-active chromophore as the building block. The structural characterization and photophysical properties are systematically studied. Owing to intrinsic twisted conformation and AIE feature of tetraphenylethylene-tetrazole ligand, CUST-805 achieves the visible and reversible PCL from blue to green switched by different external stimuli. The transformation between crystalline and amorphous states is proved to be the origin of present PCL behavior. Moreover, on basis of electron and energy transfer quenching mechanism, the highly selective and sensitive sensor based on CUST-805 is realized, showing the low detection limit of 0.29 ppm towards 2,4,6-trinitrophenol.