Metal cation-dependent helicity of two 1-D heterometal chains constructed from pyridine-2,6-dicarboxylate

Two interesting 1D heterometal chain-like compounds from pyridine-2,6-dicarboxylic acid (H(2)PDA) and AgNO3 as well as ZnCl2/SmCl3, namely [ZnAg(PDA)(2)(mu(2)-H2O)center dot(H3O)(+)center dot(H2O)(0.25)](n) (1) and [SmAg(PDA)(2)(H2O)(3)center dot 3H(2)O]n (2), have been solvothermally synthesized by fine control synthetic conditions, and structurally characterized. The results reveal that 1D rac-helical chain 1 containing two independent single-stranded single-helical P-helical and M-helical chains crystallized in the tetragonal 14(1)/a space groups, in which the octahedral Zn2+ center in 1 coordinated to two pyridyl nitrogen atoms and four carboxyl oxygen atoms from two chelating PDA(2-) ligands, while the distorted tetrahedral Ag+ center in 1 ligated to two aqueous oxygen atoms and two carboxyl oxygen atoms from two bridging PDA(2-) ligands. Under the same reaction conditions except the reactant of SmCl3 replacing ZnCl2, 1-D meso-helical chain 2 with monoclinic P2(1)/n space group, consisting of two adjacent three-stranded single-helical P and M chains connected through Ag-O bonds, was obtained. Each Sm3+ ion in 2 was chelated to two PDA(2-) anions as tridentate (ONO) ligands and three water molecules that completed the nine-coordinated environment around Sm3+. The coordination sphere of Ag+ was finished by five carboxyl O atoms from three PDA(2-) ligands with highly distorted trigonal bipyramidal geometry. Obviously, different helicity between 1 and 2 closely related to the radius and coordi numbers of the 3d/4f metal cation ions. Moreover, the fluorescent propeties of compounds 1 and 2 were also studied. (C) 2016 Elsevier B.V. All rights reserved.