Various pH-Dependent Copper(II) Coordination Architectures Constructed from N,N′-Di(3-pyridyl)succinamide and Two Different Dicarboxylates

Abstract

Using a bis-pyridyl-bis-amide N,N 0 -di(3-pyridyl)succinamide (L) and two dicarboxylates as mixed ligands, four 2D copper(II) metalÀorganic networks, formulated as [Cu(1,, and [Cu(2,5-tdc)(L)]Á2H 2 O (4) (L ¼ N,N 0 -di(3-pyridyl)succinimide; 1,4-H 2 chdc ¼ 1,4-cyclohexanedicarboxylic acid; 2,5-H 2 tdc ¼ thiophen-2,5-dicarboxylic acid) have been hydrothermally synthesized under different pH conditions, and characterized by IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Compound 1, formed at pH 5.4, contains two rare types of left-, right-handed [Cu-L] n helix chains, which are further connected by [Cu-1,4-chdc] n zigzag chains, affording a 2D wave-like polymeric network. Compound 2 was obtained at pH 5.9, and shows a 2D square-grid layer constructed from zigzag [Cu-L] n chains and linear [Cu-1,4-chdc] n chains. Compounds 3 and 4 possess a similar 2D grid layer to that of 2 with 4 4 -sql topology, formed at pH 4.8 and 5.4 respectively, and are constructed from zigzag [Cu-L] n chains and linear [Cu-2,5-tdc] n chains. The effects of pH and secondary dicarboxylates on the diversity of structures are discussed. In addition, the thermal stabilities, photoluminescence properties, and photocatalytic activity of compounds 1-4 were also studied.