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 [Ni ₂(3-bptpa) ₄(1,2-BDC) ₂(H ₂O) ₂] ( 1), [Ni(3-bptpa)(IP)(H ₂O) ₂]·H ₂O ( 2), [Ni(3-bptpa)(5-MIP)(H ₂O) ₂]·H ₂O ( 3), [Ni(3-bptpa)(5-NIP)(H ₂O)] ( 4), [Ni(3-bptpa)(5-AIP)]·2H ₂O ( 5), [Ni ₂(OH)(3-bptpa)(1,3,5-BTC)]·DMA·5H ₂O ( 6), [Cu(3-bptpa)(5-MIP)]·3H ₂O ( 7), [Cu(3-bptpa)(5-AIP)(H ₂O) _0.25]·H ₂O ( 8), and [Cu(3-bptpa)(1,3,5-HBTC)] ( 9) (1,2-H ₂BDC = 1,2-benzenedicarboxylic acid, H ₂IP = 1,3-benzenedicarboxylic acid, 5-H ₂MIP = 5-methylisophthalic acid, 5-H ₂NIP = 5-nitroisophthalic acid, 5-H ₂AIP = 5-aminoisophthalic acid, DMA = N, N′-dimethylacetamide, and 1,3,5-H ₃BTC = 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 6 ³ [Ni(5-AIP)] honeycomblike sheets. Complex 6 is a 3,5-connected three-dimensional (3D) framework derived from bimetallic nodes and 6 ³ [Ni ₂(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.