A series of Zn(II) and Cd(II) coordination polymers based on flexible bis-[(pyridyl)-benzimidazole] ligand and different carboxylates: syntheses, structures, and photoluminescent properties

Eight new coordination polymers, namely, [Zn(m-bdc)(L)] (1), [Zn(NH2-bdc)(L)] (2), [Zn-3(p-bdc)(3)(L)]center dot 2H(2)O (3), [Zn-3(btc)(2)(L)(H2O)]center dot H2O (4), [Cd(o-bdc)(L)(H2O)] (5), [Cd(m-bdc)(L)] (6), [Cd(p-bdc)(L)(H2O)] (7) and [Cd-2(btda)(L)]center dot H2O (8) (m-H(2)bdc = 1,3-benzenedicarboxylic acid, NH2-H(2)bdc = 5-NH2-1,3-benzenedicarboxylic acid, p-H(2)bdc = 1,4-benzenedicarboxylic acid, H(3)btc = 1,3,5-benzenetricarboxylic acid, o-H(2)bdc = 1,2-benzenedicarboxylic acid, btda = 3,3',4,4'-benzophenonetetracarboxylic dianhydride and L = 1,1'-(1,4-butanediyl)- bis[2-(3-pyridyl)benzimidazole]), have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction. Compounds 1 and 2 display bilayer structures. The neighboring layers of 2 are further linked by hydrogen-bonding interactions to form a 3D supramolecular architecture. Compound 3 shows a 3D 8-connected (3(6)center dot 4(10)center dot 5(11)center dot 6) topology. Compound 4 exhibits a 3D (3,4)-connected (5 center dot 7 center dot 8)(2)(4(2)center dot 6 center dot 7(2)center dot 8)(2)(4(2)center dot 5(2)center dot 6 center dot 7)(2)(7(2)center dot 8(4)) net. Compound 5 reveals a layer. The layers are further connected by pi-pi interactions to give rise to a 3D supramolecular architecture. Compound 6 shows a 3D framework with (3,5)- connected (4(2)center dot 6)(4 center dot 10(2))(2)(4(3)center dot 6 center dot 8(4)center dot 10(2)) topology. The structure of compound 7 is a 3D (3,4)-connected framework with (4 center dot 8(2))(4 center dot 9 center dot 10)(2)(4(2)center dot 8(2)center dot 9(2)center dot 10(4)) topology. Compound 8 displays a 3D (3,4)-connected (4 center dot 10(2))(2)(4(2)center dot 8(2)center dot 10(2))(4(2)center dot 8(4))(2) topology. Their photoluminescent behaviours have been investigated in detail.