A series of Cu(ii) and Cd(ii) coordination polymers constructed by 3,5-dinitrosalicylic acid and flexible bis(triazole) ligands containing different spacers

Abstract

A series of coordination polymers based on 3,5-dinitrosalicylic acid (H₂sal) and nine flexible bis(triazole) ligands, namely, [Cu₄(sal)₄(L1)₂(H₂O)]·2H₂O (1), [Cu₄(sal)₄(L2)₂(H₂O)] (2), [Cu₂(sal)₂(L3)(H₂O)] (3), [Cu₂(sal)₂(L4)(H₂O)] (4), [Cu₅(sal)₄(OH)₂(L5)₂(H₂O)₃]·H₂O (5), [Cu(sal)(L6)] (6), [Cu₂(sal)₂(L7)] (7), [Cu(sal)(L8)]·0.5H₂O (8), [Cd₂(sal)₂(L1)(H₂O)₂] (9), [Cd₂(sal)₂(L7)₃] (10) and [Cd₄(sal)₄(L9)₄] (11), where L1 = 1,2-bis(1,2,4-triazol-1-yl)ethane, L2 = 1,3-bis(1,2,4-triazol-1-yl)propane, L3 = 1,4-bis(1,2,4-triazol-1-yl)butane, L4 = 1,5-bis(1,2,4-triazol-1-yl)pentane, L5 = 1,5-bis(1,3,4-triazol-1-yl)pentane, L6 = 1,6-bis(1,2,4-triazol-1-yl)hexane, L7 = 1,10-bis(1,2,4-triazol-1-yl)decane, L8 = 1,4-bis((1H-1,2,4-triazol-1-yl)methyl)benzene and L9 = 1,1′-(2,2′-oxybis(ethane-2,1-diyl))bis(1H-1,2,4-triazole), have been synthesized and characterized by single crystal X-ray diffraction, elemental analyses, IR spectra, PXRD spectra and TG analysis. Compounds 1 and 4 possess one-dimensional (1D) double chains. Compounds 2, 3 and 5 show two-dimensional (2D) 4⁴ networks. Compound 6 displays a three-dimensional (3D) uninodal eight-connected self-penetrating framework with the 4²⁰6⁸ topology. Compound 7 reveals a 2D 2-fold interpenetrating 4⁴-sql network. Compounds 8 and 9 display 2D undulated layers. Compound 10 shows a 1D chain. Compound 11 reveals a discrete tetranuclear cluster. The UV-vis spectra and optical energy gap of 1–11 have also been investigated in detail.