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: [CuII (HL)NaI(NO3)(MeOH)] (1), [CuII(HL)ZnII(H2O)(NO3)](NO3) (2), [CuII(HL)HgII(Cl)2] (3), [CuII(H2O)(HL)SmIII(NO3)3] (4), [CuII(H2O)(HL)BiIII(NO3)3] (5), [CuII(HL)PbII(NO3)2] (6) and [CuII(HL)CdII(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 P21/n space group, 4, 5 and 7 in the monoclinic P21/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 CuII metal ion is trapped in N2O2 compartment of the Schiff-base ligand, while the second metal ion is present in the larger and open O4 [O(phenoxo)2O(methoxy)2] compartment. NaI and ZnII ions in 1 and 2, respectively, are six coordinated, while PbII ion in 6 and CdII ion in 7 are eight coordinated. HgII ion in 3 is six coordinated, while both SmIII and BiIII 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 O4 compartment.

A new series of heterodinuclear CuII–MI/II/III compounds show diverse supramolecular architectures governed by H-bonding interactions of free aliphatic –OH group.Figure optionsDownload as PowerPoint slideHighlights
► Seven heterodinuclear CuIII–MI/II/III complexes with new bicompartmental ligands.
► Diverse supramolecular aggregates governed by H-bonding interactions of free aliphatic –OH group.
► Bismuth(III) with samarium(III) are isostuctural and isomorphous.
► A rare feature of helical twisting for the coordinated Schiff-base in CuII–HgII is found in its crystal structure.