Construction of Metallosupramolecular Coordination Complexes: From Lanthanide Helicates to Octahedral Cages Showing Single-Molecule Magnet Behavior.

The construction of metallosupramolecular complexes toward interesting topological structures is a critical challenge for chemists. The fluctuation in the synthetic strategy, by keeping the same metal-ligand combination, has proved a very significant approach to construct metallosupramolecular architectures. Herein, by varying the reaction conditions four new DyIII-supramolecular complexes based on a flexible dihydrazone ligand H2L (H2L = bis(2-hydroxy-3-methoxybenzylidene)adipohydrazide) in cooperation with different anions and solvents having formulas [Dy4L4(μ2-N3)2](NO3)2·6CH3OH·2H2O (1), [Dy8L8(μ2-CH3OH)4]Cl8·6CH3OH·14H2O (2), [Dy12L12(μ2-OH)2(OH)6(CH3O)2](NO3)2·2CH3OH·14H2O (3), and [Dy12L12(μ2-OH)2(NO3)2(OH)3(CH3O)](NO3)4·22H2O (4), have been successfully synthesized and their crystal structures confirmed by single crystal X-ray diffraction studies. The structural study reveals that 1 and 2 have quadruple-stranded helicate and dual triple-stranded helicate supramolecular structures, respectively, while 3 and 4 display "octahedron" cagelike supramolecular structures. The magnetic studies reveal that complexes 1-3 exhibit slow magnetic relaxation behavior, while complex 4 displays a series of typical frequency-dependent relaxation signals at 0 Oe applied dc field which is a rare case in polynuclear 4f single-molecule magnet (SMM) family to date. Interestingly, the distinct magnetic dynamic behavior was noticed for nearly isoskeletal complexes 3 and 4, which can be attributed to the modification of the coordination environment around DyIII ions.