Metal/Carboxylate-Induced Versatile Structures of Nine 0D → 3D Complexes with Different Fluorescent and Electrochemical Behaviors.

Abstract

To investigate the effect of the polycarboxylates and metal ions on the assembly and structures of complexes based on a thiophene-containing bis-pyridyl-bis-amide N,N′-bis(pyridine-3-yl)thiophene-2,5-dicarboxamide (3-bptpa) ligand, nine 0D → 3D complexes of [Ni2(3-bptpa)4(1,2-BDC)2(H2O)2] (1), [Ni(3-bptpa)(IP)(H2O)2]·H2O (2), [Ni(3-bptpa)(5-MIP)(H2O)2]·H2O (3), [Ni(3-bptpa)(5-NIP)(H2O)] (4), [Ni(3-bptpa)(5-AIP)]·2H2O (5), [Ni2(OH)(3-bptpa)(1,3,5-BTC)]·DMA·5H2O (6), [Cu(3-bptpa)(5-MIP)]·3H2O (7), [Cu(3-bptpa)(5-AIP)(H2O)0.25]·H2O (8), and [Cu(3-bptpa)(1,3,5-HBTC)] (9) (1,2-H2BDC = 1,2-benzenedicarboxylic acid, H2IP = 1,3-benzenedicarboxylic acid, 5-H2MIP = 5-methylisophthalic acid, 5-H2NIP = 5-nitroisophthalic acid, 5-H2AIP = 5-aminoisophthalic acid, DMA = N,N′-dimethylacetamide, and 1,3,5-H3BTC = 1,3,5-benzenetricarboxylic acid) have been hydrothermally/solvothermally synthesized and structurally characterized by IR, thermogravimetric, powder X-ray diffraction, and single-crystal X-ray diffraction. Complex 1 is a zero-dimensional (0D) bimetallic complex. Complexes 2 and 3 feature two similar one-dimensional ladderlike structures. Complex 4 displays a two-dimensional (2D) 4-connected network based on single-metallic nodes. Complex 5 shows a 2D double-layer structure containing a pair of 63 [Ni(5-AIP)] honeycomblike sheets. Complex 6 is a 3,5-connected three-dimensional (3D) framework derived from bimetallic nodes and 63 [Ni2(OH)(1,3,5-BTC)] honeycomblike sheets. Complex 7 displays a 2D 4-connected grid based on bimetallic nodes. Complex 8 features a 2D double-layer structure based on two 4-connected [Cu(3-bptpa)(5-AIP)] sheets and bridging coordinated water molecules. Complex 9 is a 2D structure extended by incomplete deprotonation of 1,3,5-HBTC and 3-bptpa linkers. The effect of the metal ions and polycarboxylates on the structures of the title complexes was discussed, and the fluorescent properties of 1–9 were investigated. The carbon paste electrodes bulk-modified by complexes 3, 5, and 6–9 show different electrocatalytic activities for the oxidation of ascorbic acid as well as the reduction of hydrogen peroxide, nitrites, and bromates.