Three new Zn(ii) coordination polymers for highly selective and sensitive detection of Fe3+

Water pollution caused by Fe3+ is a severe problem in the modern world. Therefore, quantitative analysis of Fe3+ concentration in water is necessary to monitor water quality. In recent years, coordination polymers (CPs) have been proven to be a class of excellent candidates for luminescent sensors. In this work, three CPs, namely, {[Zn-3(L1)(2)(H2O)(3)]& BULL;0.5H(2)O}(n) (1), {[Zn-3(L1)(2)(dib)(2.5)(H2O)]& BULL;0.5H(2)O}(n) (2), and {[Zn-2(L2)(OH)(H2O)]& BULL;0.5H(2)O}(n) (3), have been synthesized under hydrothermal conditions (H(3)L1 = 5-((2-carboxyphenoxy)methyl)benzene-1,3-dioic acid, H(3)L2 = 5-((3-carboxyphenoxy)methyl)benzene-1,3-dioic acid, and dib = 1,4-di(1H-imidazol-1-yl)butane). Compound 1 shows a novel (3,12)-connected 3D framework based on a hexanuclear Zn(ii) cluster with the point symbol of {4(3)}(4){4(20)& BULL;6(28)& BULL;8(18)}. Compound 2 reveals a (3,3,4,4)-connected 3D framework with the {6 & BULL;9(2)}(2){6(4)& BULL;8 & BULL;10}{6(4)& BULL;8 & BULL;9}{9 & BULL;11 & BULL;12} topology. Compound 3 exhibits a (3,6)-connected 2D layer based on a tetranuclear Zn(ii) cluster with the {4(3)}(2){4(6)& BULL;6(6)& BULL;8(3)} topology. The luminescence responses of compounds 1-3 towards Fe3+ were investigated in aqueous solutions. The results show that compounds 1-3 are good luminescent sensors for detection of Fe3+. The low limits of detection (LOD) for Fe3+ are 4.07, 1.14, and 40.70 mu M, respectively.