Magnetism of Self assemblies Consisting of Single-molecule Magnets

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The studies aiming at the assemblization of single-molecule magnets (SMMs) based on the strategy of heterospin system have been proceeded. Dumbbell-type dinuclear single-molecular magnet was prepared by using the cobalt complex with tridentate pyridine ligand having dimethylamino groups at 2-and 6-position and dipyridildiazomethane (D1py_2). After irradiation, the complex showed slow magnetic relaxation characteristic to SMM in ac magnetic susceptibility measurements. However, the crystal amenable to X-ray crystal structure analysis could not be obtained. The cobalt complex obtained by mixing Co(p-tolsal)_2 and D1py_2 in 1:1 ratio, provide the SEM picture suggesting the formation of ID chains. In the dc magnetic susceptibilities measurement of the crystal sample after irradiation, the result indicating that the eight units of the cobalt ion and carbene interact ferromagnetically, was obtained. Furthermore, this cobalt complex showed a slow magnetic relaxation with U_<eff> = 87 K in ac magnetic susceptibility measurement and a hysteresis loop with H_c = 900 Oe in dc magnetic susceptibility measurement. These results indicate the formation of a ID chain. The complexes of Co(hfaci)_2, which is analogous to Co(hfac)_2, with D1py_2 and D2py_2 have a ID chain and a 2:2 cyclic structure, respectively, which were determined by X-ray structure analysis. They showed unique magnetic behaviors strongly affected by the interchain and intermolecular antiferromagntic interactions, respectively.