| Research Abstract |
In them studies, we worked on rational synthesis of stable multinuclear transition metal clusters in cage-type ligand (L) for development of new active metal sites of artificial enzyme molecules, processing reactions without their decomposition. At fast, we succeeded in synthesizing a tricopper complex with a motif of the four-election O_2-reduction site in multicopper enzymes such as Laccase. Under Ar atmosphere, [Cu^<II>_3L(OH)_2(H_2O)](ClO_4)_4 (1) was made as the aqua-and dihydroxo-binding tricopper (II) species, which can catpture various anions. 1 also reacted with atmospheric carbon dioxide to give [Cu^<II>_3L(OH)_2(H_2O)](ClO_4)_4, (2), immediately. Furthermore, the cage-type ligand, L, can be applied to other transition metal ions, and we succeeded in synthesizing the cluster-type transition metal complexes of manganese(II), tripalladium(II), and cobalt(II) ions. In the trimanganese complex, [Mn_3(L)(CO_3)(OCOCH_3)(CH_3OH)_3(ClO_4)] (ClO_4) (3) , it is considered that the carbonate anion was formed from carbon dioxygen reacted with the precursor, aqua-and dihydroxo-binding trimmganese(II) center, which may be one of the best candidates for an artificial oxygen-evolving complex. In addition, we succeeded in constructing tripalladium complex (5), having the almost same structure as that of tricopper complex 2, taking carbon dioxide inside the tripalladium core of 5. In 5, the guest molecule non-covalently interacted with the cage-type ligand inside. Even in ram of a tricobalt(II) complex, similar capturing behavior for anions were observed. Construction of the other trinuclear complexes and further complicated metal centers were also newly approached in them studies
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