Four cobalt(II) coordination polymers based on a flexible N,N′-bis(3-pyridinecarboxamide)-1,6-hexane ligand: Modulation of crystal architectures through the substituent groups of isophthalates

Four cobalt(II) mixed ligand coordination polymers based on the flexible N,N'-bis(3-pyridinecarboxamide)-1,6-hexane (3-dpyh) and four isophthalates with different substituent groups, namely [Co(3-dpyh) (5-HIP)(H2O)(3)]center dot H2O (1), [Co(3-dpyh)(5-NIP)]center dot H2O (2), [Co(3-dpyh)(5-MIP)]center dot H2O (3) and [Co(3-dpyh)(0.5) (5-AIP)(H2O)]center dot 2H(2)O (4), have been hydrothermally synthesized and structurally characterized (5-H2HIP = 5-hydroxyisophthalic acid, 5-H2NIP = 5-nitroisophthalic acid, 5-H2MIP = 5-methylisophthalic acid, 5-H(2)AIP = 5-aminoisophthalic acid). X-ray diffraction analyses reveal that complex 1 is a chain constructed from a [Co-3-dpyh](n) meso-helical chain and 5-HIP anions, in which each 5-HIP anion adopts a monodentate mode coordinating to one Co(II) ion. The isostructural complexes 2 and 3 are assembled from 5-NIP and 5-MIP anions, respectively, featuring a 2D 3,5-connected network with the {4(2).6(7).8}{4(2).6} topology, in which the two carboxyl groups of dicarboxylates exhibit mu(1):eta(1)-eta(1) and mu(2):eta(1)-eta(1) modes. When the 5-AIP anion is utilized in 4, a different 2D (3,4)-connected {4(2).6(3).8}{4(2).6} network is obtained, in which the two carboxyl groups of AIP exhibit mu(1):eta(1)-eta(1) and mu(1):eta(1)-eta(0) modes, and the N atom of AIP also coordinates to the Co(II) ion. The influence of the substituent groups of the isophthalates on the structures has been discussed in detail. The fluorescent, electrochemical and photocatalytic properties of complexes 1-4 have also been investigated. (C) 2014 Elsevier Ltd. All rights reserved.