Multifunctional Cobalt(II) Coordination Polymers Tuned by Flexible Bis(pyridylamide) Ligands with Different Spacers and Polycarboxylates

Ten multifunctional cobalt(II) coordination polymers with the formulas of [Co(L1)0.5(5-AIP)]·H2O (1), [Co(L2)(5-AIP)(H2O)2] (2), [Co(L3)0.5(5-AIP)] (3), [Co(L4)0.5(5-AIP)(H2O)]·2H2O (4), [Co(L5)(5-AIP)] (5), [Co(HBTC)(L3)]·H2O (6), [Co(HBTC)(L6)(H2O)]·3H2O (7), [Co(L2)(1,3-BDC)(H2O)2] (8), [Co2(L3)2(1,3-BDC)2]·4H2O (9), and [Co2(L4)1.5(1,2-BDC)(μ2-OH)(μ3-OH)(H2O)]·H2O (10) have been prepared by a hydrothermal technique employing six flexible bis(pyridylamide) ligands with different spacers (L1 = N,N′-bis(3-pyridyl)oxamide, L2 = N,N′-bis(3-pyridyl)malonamide, L3 = N,N′-di(3-pyridyl)succinamide, L4 = N,N′-bis(3-pyridyl)adipamide, L5 = N,N′-bis(3-pyridyl)heptandiamide, L6 = N,N′-bis(3-pyridyl)sebacicdiamide) and four aromatic polycarboxylic acids mixed ligands (5-H2AIP = 5-aminoisophthalic acid, H3BTC = 1,3,5-benzenetricarboxylic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid, and 1,2-H2BDC = 1,2-benzenedicarboxylic acid). Compound 1 exhibits a two-dimensional (2D) double-layer network. Compounds 2 and 8 are isostructural and possess one-dimensional (1D) circle-connecting-circle chain structures derived from 1D [Co(L2)]n "Ω"-like chain and 1D [Co(5-AIP)]n/[Co(1,3-BDC)]n wavelike chain. Compound 3 possesses a 3,8-connected three-dimensional (3D) coordination framework with {42.6}2{44.610.79.85} topology. Compound 4 is a 2D network containing a ladder-like chain. Compound 5 reveals a novel 3-fold interpenetrating CdSO4-like framework. Compound 6 is a double-layer coordination network with a (3,5)-connected {42·67·8}{42·6} topology. Complex 7 shows a 2D (4,4) grid layer. Compound 9 features a 2-fold interpenetrating 3D α-Po-related topological framework. Compound 10 is a 6-connected 3D coordination polymer with a {412.63} topology. The spacer length of the bis(pyridylamide) ligands, as well as the substituent group and carboxyl group number of polycarboxylates, shows a significant effect on the ultimate architectures of various cobalt(II) compounds 1–10. The electrochemical behaviors of carbon paste electrodes (CPEs) bulk-modified by compounds 1–10 and the electrocatalytic activities of 1-, 6-, 9-, 10-CPEs have been investigated. The photocatalytic properties of compounds 1–10 toward the degradation of methylene blue (MB) in visible light irradiation have been investigated. The variable temperature magnetic susceptibilities for compounds 3, 5, 9, and 10 indicate the existence of antiferromagnetic exchange interactions.