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

Abstract

Three intriguing metal-cluster based coordination polymers (MCOFs) {[Cu₄(OH)₂(itp)₂(btc)₂(H₂O)₄][Cu(H₂O)₄(Hbtc)]₂·4H₂O}_n (1), {[Cu₄(OH)₂(itp)₂(btc)₂]·2EtOH·2H₂O}_n (2) and {[Cu₄(OH)₂(itp)₂(sip)₂(H₂O)₄]·4H₂O}_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 [Cu₄(μ₃-OH)₂] and Cu₁ cores with a Schläfli symbol of (6²·8)₂(6·8⁴·10) and an unprecedented 2D → 3D polythreaded motif. 2 shows an unusual (3,10)-connected 3D network based on the tetranuclear copper(II) cluster [Cu₄(μ₃-OH)₂] with the Schläfli symbol of (3·4·5)₂(3⁴·4⁶·5¹⁰·6¹⁵·7¹⁰). 3 exhibits a 2D (4,4) network based on tetranuclear copper(II) clusters [Cu₄(μ₃-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.