Two zinc(ii)-based coordination polymers as luminescent sensors for detecting salicylaldehyde with high sensitivity and selectivity†

Two zinc(II)-based coordination polymers, namely, {[Zn₂L₂(bmib)]·DMA}_n (1) and {[ZnL(bipd)]}_n (2). (H₂L = 5-{(anthracen-9-ylmethyl)amino}isophthalic acid, bmib = 1,4-bis(2-methyl-imidazol-1-yl)butane, bipd = 3,5-bi-1H-imidazol-1-ylpyridine, DMA = N,N-dimethylacetamide), were synthesized by a hydrothermal method. Single-crystal X-ray diffraction analysis showed that in 1 and 2, the carboxylic acid ligand possesses abundant coordination models: 1 shows a tangled one-dimensional (1D) chain structure and through weak interactions forms a 2D structure, while 2 possesses a two-dimensional (2D) structure. Fluorescence experiments showed that 1 and 2 can be used as good fluorescent sensors for selectively detecting SA with a detection limit of 0.87 and 27.03 μM, respectively. Notably, SA can be further identified via the naked eye, which has significant potential for practical applications. In addition, mechanism studies showed that detection of SA by 1 and 2 is attributed to a competition absorption mechanism.