Diversity in supramolecular self-assembly through hydrogen-bonding interactions of non-coordinated aliphatic -OH group in a series of heterodinuclear CuIIM (M = NaI, ZnII, HgII, SmIII, BiIII, PbII and CdII)

The syntheses, and structural characterization of seven heterodinuclear complexes: [Cu-II (HL)Na-I(NO3) (MeOH)] (1), [Cu-II(HL)Zn-II(H2O)(NO3)](NO3) (2), [Cu-II(HL)Hg-II(Cl)(2)] (3), [Cu-II(H2O)(HL)Sm-III(NO3)(3)] (4), [Cu-II(H2O)(HL)Bi-III(NO3)(3)] (5), [Cu-II(HL)Pb-II(NO3)(2)] (6) and [Cu-II(HL)Cd-II(NO3)(2)] (7) are reported, where H3L = N,N'-bis(3-methoxysalicylaldiimine)-1,3-propylene-2-ol. Compounds 1 and 3 crystallize in the monoclinic P2(1)/n space group, 4, 5 and 7 in the monoclinic P2(1)/c space group, while the space group of complexes 2 and 6 is triclinic P1. The X-ray crystallography reveals that the structures of all the complexes consist of diphenoxo-bridged heterometallic cores in which Cu-II metal ion is trapped in N2O2 compartment of the Schiff-base ligand, while the second metal ion is present in the larger and open O-4 [O(phenoxo)(2)O(methoxy)(2)] compartment. Na-I and Zn-II ions in 1 and 2, respectively, are six coordinated, while Pb-II ion in 6 and Cd-II ion in 7 are eight coordinated. Hg-II ion in 3 is six coordinated, while both Sm-III and Bi-III ions in 4 and 5, respectively, are surrounded by 10 oxygen atoms involving four O atoms from the outer compartment of the ligand and six from three chelating nitrates. In all the cases, non-coordinated -OH group plays significant role in the construction of diverse supramolecular aggregates through hydrogen bonding: two dimensional (2D) in 1 and 3, one dimensional (1D) in 2, 4, 5 and 6, while dimeric in 7. In addition to the structural diversity, the structural resemblance of bismuth(III) with member of a lanthanum family, samarium(III), is noted. In fact, they are found to be isostructural and isomorphous in the present study. Most importantly, compound 3 exhibits a rare feature of helical twisting for the coordinated Schiff-base ligand that arises due to the fact that the metal ion is too large to fit into the wider O-4 compartment. (C) 2013 Elsevier B.V. All rights reserved.