Three multi-responsive luminescent Zn-CPs for the detection of antibiotics/cations/anions in aqueous media

Abstract

Development of luminescent coordination polymers (LCPs) for effective detection of the environmental pollutants is urgent and important for human health and environmental protection. Three novel Zn-LCPs, {[Zn¹(L)(4,4′-bbibp)]–[Zn²(L)(4,4′-bbibp)]}_n [YMUN6 (for Youjiang Medical University for Nationalities)], [Zn(L)(1,4-bimb)]_n (YMUN7), and [Zn(L)(4,4′-bidpe)]_n (YMUN8), were fabricated from flexible dicarboxylic acid 1,3-bis(4′-carboxylphenoxy)benzene (H₂L) and different imidazole ligands [4,4′-bbibp = 4,4′-bis(benzimidazol-1-yl)biphenyl, 1,4-bimb = 1,4-bis(imidazol-1ylmethyl)benzene, 4,4′-bidpe = 4,4′-bis(imidazolyl)diphenyl ether] using solvothermal conditions. They were characterized using X-ray diffraction (XRD), infrared (IR), thermogravimetric (TG), powder X-ray diffraction (PXRD), and photoluminescence (PL) spectroscopic techniques. YMUN6 possessed the “ABAB” interpenetrating 2D complanate structure. YMUN7 showed a three-interpenetrating 2D network. YMUN8 displayed a hcb 3-connected 3-fold interpenetrated 2D network. Photoluminescent properties of YMUN6–8 were investigated, and 6–8 served as “turn off” sensors that could detect chlortetracycline (Chl), Ag⁺, and Cr₂O₇²⁻ in an aqueous solution with simultaneous high efficiency and sensitivity. Notably, the investigation of Ag⁺ sensing was most focused on lanthanide metal LCPs, and Zn-LCPs have rarely been reported in this direction. Furthermore, selectivity and recyclability were also investigated.