Metal-organic coordination architectures with 3-pyridin-3-yl-benzoate: crystal structures, fluorescent emission and magnetic properties

Reactions of 3-pyridin-3-yl- benzoic acid (HL) with metal nitrates under hydrothermal conditions yield seven new coordination polymers: Ni(L)(2)(H2O)(2) (1), [Ni(L)(2)](H2O) (2), Co(L)(2)(H2O)(2) (3), [Zn(L)(2)](H2O) (4), Cu(L)(2) (5), Cd( L)(2) (6) and Gd-2(L)(6)( H2O)(4) (7). A systematic investigation on coordination chemistry of the ligand and the significant function of supramolecular interactions in managing the resultant crystalline networks has been carried out. On the basis of the X-ray diffraction analysis of these complexes, the results show that complexes 1 - 5 and 7 form similar one-dimensional (1D) double-chain coordination arrays, among which 1 and 3, as well as 2 and 4, are isostructural. Remarkably, distinct network architectures are further constructed with the aid of weak secondary interactions. Amongst them, complexes 1, 3 and 5 exhibit the classical alpha-polonium networks, while complexes 2 and 4 present the ( 3,4)- connected two-dimensional layers. In 7, the intermolecular p - p stacking interactions lead to the formation of a double- strand structure. The Cd-II complex 6 assembles into a three-dimensional metal - organic framework exhibiting a unique 6-connected roa topology. The trans-configuration of L ligand is only found in the case of 6, whereas the cis- ligands are generally observed in these complexes. The fluorescent emission properties of 4 and 6 as well as the magnetic property of 7 have also been investigated.