Versatile carboxylate-directed structures of ten 1D → 3D Ni(<scp>ii</scp>) coordination polymers: fluorescence behaviors and electrochemical activities

To study the effects of carboxylates on the assembly and structures of Ni(II) coordination polymers (CPs) based on a phenyl/methylene-mixed-bridged bis-pyridyl-bis-amide [N,N′-bis(4-methylenepyridin-4-yl)-1,4-benzenedicarboxamide] (L) ligand, ten 1D → 3D Ni(II) CPs, namely [Ni(L)(2-NB)2(H2O)2] (1), [Ni(L)(4-NB)2(H2O)2] (2), [Ni(L)2(2-MOB)2] (3), [Ni(L)2(3-CB)2] (4), [Ni(L)(2-CP)(H2O)] (5), [Ni(L)(5-NIP)(H2O)2]&#183;2H2O (6), [Ni(L)(3-NP)(H2O)2] (7), [Ni(L)(4,4′-OBA)]&#183;H2O (8), [Ni(L)(1,4-BDC)(H2O)2]&#183;2H2O (9) and [Ni(L)(1,4-CHDA)(H2O)2]&#183;4H2O (10) [2-nitrobenzoic acid (2-HNB), 4-nitrobenzoic acid (4-HNB), 2-methoxybenzoic acid (2-HMOB), 3-chlorobenzoic acid (3-HCB), 2-carboxyphenylacetic acid (2-H2CP), 5-nitroisophthalic acid (5-H2NIP), 3-nitrophthalic acid (3-H2NP), 4,4′-oxybis(benzoic acid) (4,4′-H2OBA), 1,4-benzenedicarboxylic acid (1,4-H2BDC) and trans-1,4-cyclohexanedicarboxylic acid (1,4-H2CHDA)], have been hydrothermally synthesized with various carboxylates and structurally characterized by IR, PXRD and X-ray single-crystal diffraction. 1 and 2 are similar 1D coordination polymers. 3 and 4 feature similar 2D coplanar 4,4-connected networks extended by single L linkers. 5 displays a 2D wave-like 4,4-connected network based on L and 2-CP mixed linkers. 6 shows a 2D 4,4-connected structure derived from L and 5-NIP mixed spacers. 7 is a CdSO4 type 4-connected 3D framework. 8 displays a 2D → 3D parallel polycatenation array based on 2D (4,4)-connected wave-like coordinated layers. 9 and 10 feature similar 2D → 3D inclined polycatenation arrays based on 2D (4,4)-connected coplanar networks. The effects of the carboxylates on the structures of the title complexes are discussed in detail. The solid-state luminescent and fluorescent sensing properties of 1–10 for Fe3+ ions were investigated. Moreover, the effects of 1, 5 and 7 on the fluorescence properties of bovine serum albumin (BSA) and the electrocatalytic activities of carbon paste electrodes (CPEs) bulk-modified with 1, 3, 5, 7 and 9 for the reduction of hydrogen peroxide, bromate and nitrite were studied.