Construction of three coordination polymers based on tetranuclear copper(II) clusters: syntheses, structures and photocatalytic properties

Three intriguing metal-cluster based coordination polymers (MCOFs) {[Cu-4(OH)(2)(itp)(2)(btc)(2)(H2O)(4)][Cu(H2O)(4)(Hbtc)](2)center dot 4H(2)O}(n) (1), {[Cu-4(OH)(2)(itp)(2)(btc)(2)]center dot 2EtOH center dot 2H(2)O}(n) (2) and {[Cu-4(OH)(2)(itp)(2)(sip)(2)(H2O)(4)]center dot 4H(2)O}(n) (3) were synthesized by the reaction of 1-imidazol-1-yl-3-(1,2,4-triazol-4-yl) propane (itp), 1,3,5-benzenetricarboxylate (btc) or 5-sulfoisophthalate (sip) and CuCl2 using a hydrothermal method. 1 consists of an unprecedented (3,4)-connected 2D network based on the tetranuclear copper(II) clusters [Cu-4(mu(3)-OH)(2)] and Cu-1 cores with a Schlafli symbol of (6(2).8)(2)(6.8(4).10) and an unprecedented 2D -> 3D polythreaded motif. 2 shows an unusual (3,10)-connected 3D network based on the tetranuclear copper(II) cluster [Cu-4(mu(3)-OH)(2)] with the Schlafli symbol of (3.4.5)(2)(3(4).4(6).5(10).6(15).7(10)). 3 exhibits a 2D (4,4) network based on tetranuclear copper(II) clusters [Cu-4(mu(3)-OH)(2)]. 1-3 are semiconducting in nature, with E-g of 2.29 eV (1), 2.27 eV (2) and 2.39 eV (3). 1-3 are universal and highly efficient photocatalysts for the degradation of organic dyes such as methyl orange (MO), methylene blue (MB) and rhodamine B (RhB) under UV irradiation, are very stable and easily separated from the reaction system for reuse.