Six tubular/helical nickel(II) coordination polymers tuned by V-like tri-pyridyl-bis-amide and dicarboxylates with different spacers

• Six new tubular/helical Ni(II) coordination polymers were hydrothermally synthesized.
• The V-like L1/L2 ligands have important effect on the tubular/helical structures.
• The spacer groups of two types of ligands have influence on the structures of 1–6.
• The electrochemical behaviors of complexes 4–6 have been reported.

Six new tubular/helical NiII coordination polymers namely, {[Ni(L1)(mip)(H2O)]·3H2O}n (1), {[Ni(L1)(hip)(H2O)3]·3H2O}n (2), {[Ni4(L1)4(oba)4(H2O)2]·10H2O}n (3), {[Ni(L2)(mip)(H2O)]·2H2O}n (4), {[Ni2(L2)2(hip)2(H2O)2]·4H2O}n (5), {[Ni(L2)(oba)(H2O)2]·H2O}n (6), [L1 = N,N′-bis(pyridin-3-yl)pyridine-2,6-dicarboxamide, L2 = N,N′-bis(pyridin-3-yl)pyridine-3,5-dicarboxamide, H2mip = 5-methylisophthalic acid, H2hip = 5-hydroxyisophthalic acid, H2oba = 4,4′-oxybis(benzoic acid)] were hydrothermally synthesized and structurally characterized by IR, PXRD and single-crystal X-ray diffraction analysis. Complexes 1, 3, 4 and 5 exhibit similar one dimensional tubular structures constructed from 28-membered [Ni-L]2 loops (L = L1 and L2) with different sizes and linear [Ni-X]n chains (X = mip, hip and oba). In complex 2, L1 ligands connect the adjacent NiII ions constructing two types of 1D chains: left-, right-helical chain [Ni–L1]n, which are further extended into a 2D supramolecular double layer by hydrogen bonding interactions. In complex 6, the L2 ligands adopting μ3-bridging mode connect adjacent NiII ions to form a 1D channel-like structure. The effects of the V-like tri-pyridyl-bis-amide and dicarboxylates on the tubular/helical structures of the title complexes were reported. In addition, the electrochemical behaviors of complexes 4–6 and thermal stabilities of complexes 1–6 were studied.

Six new tubular/helical nickel(II) coordination polymers have been synthesized from hydrothermal reactions. The V-like tri-pyridyl-bis-amide and dicarboxylates have a great influence on the tubular/helical structures of the title complexes.Figure optionsDownload as PowerPoint slide