Construction of Cu(II), Zn(II) and Cd(II) metal-organic frameworks of bis(1,2,4-triazol-4-yl)ethane and benzenetricarboxylate: syntheses, structures and photocatalytic properties

Three coordination polymers {[Cu-4(OH)(2)(btre)(1,2,3-btc)(2)(H2O)(2)]center dot 2H(2)O}(n) (1), {[Zn-4(OH)(2)(btre)(1,2,3-btc)(2)(H2O)(4)]center dot 4H(2)O}(n) (2) and {[Cd-3(btre)(1,2,3-btc)(2)(H2O)(3)]center dot 3H(2)O}(n) (3) were synthesized by the hydrothermal method using 1,2-bis(1,2,4-triazol-4-yl) ethane (btre), 1,2,3-benzenetricarboxylate.1,2,3-btc) and metal ions(Cu(II), Zn(II), and Cd(II)). 1 shows a (3,8)-connected 3D metal-organic framework based on the tetranuclear copper(II) cluster[Cu-4(mu(3)-OH)(2)] with the point symbol of (4.5(2))(3) (4(4).5(5).6(12).7(3).8(3).9). 2 exhibits a (3,8)-connected 3D metal-organic framework based on the tetranuclear zinc(II) cluster[Zn-4(mu(3)-OH)(2)] with the point symbol of (4(2).6)(3)(4(6).6(18).8(3).10). In 3, each [Cd-3(1,2,3-btc)(2)center dot H2O)] n chain connects four adjacent identical[Cd3(1,2,3-btc)(2)(H2O)] n chains through the btre bridges in four different directions, leading to an unusual 3D network. 3 shows a 4-connected 6(6) dia topological net based on the[Cd-3(H2O)(COO)(4)] trimer Cd(II) clusters. The diverse structures demonstrate that the central metal ions play the key role in the assembly of coordination polymers. 1 and 2 show good photocatalytic activity for the degradation of methyl orange. The luminescence of 2 and 3 was investigated.