|Budget Amount *help
¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1997 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1996 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Ascorbate oxidase is a complex copper protein containing the mononuclear copper site and the trinuclear copper site in the active site. In this studies, the preparation of the trinuclear copper (II) complexes as models of the active site described above was attempted in order to obtain the relationship between the structure-properties of the trinuclear copper site. The dinuclear copper (II) and nickel (II) complexes were first prepared and characterized by X-ray structural analysis, magnetic susceptibilities, visible absorption spectra.
The linear trinuclear copper (II) complexes Cu_3 (L) _2 (N_3) _2 (NO_3) _2・2H_2O・2CH_3OH (la), Cu_3 (L) _2 (N_3) _2 (ClO_4) _2・2CH_3OH (1b), Cu_3 (L) _2 (OH) _2(NO_3) _2 ・2H_2O (2a) and Cu_3 (L) _2 (OH) _2 (ClO_4) _2 (2b) (HL=Schiff base derived from 2- (2-aminoethyl) pyridine and 2,3-butanedione-2-oxime) were prepared and the crystal structures of la and 2a have been determined by X-ray crystalography. Both the complexes are centrosymmetric. The oximate
group (C=N-O^-) and azide or hydroxe ion bridge the central and terminal copper (II) ions. The configuration around central copper (II) ion of la is elongated octahedral with 2N2O atoms in the equatorial plane and 20 at the axial positions, and that of the both the terminal Cu (II) is also elongated octahedral with 4N atoms in the equatorial plane and 20 atoms at the axial positions. The coordination around the central copper (II) ion of 2a is square-planar with 40 donor set, while the termial copper (II) ion is in a square pyramidal environment with 3NO donor set in the basal plane and 0 at the axial position. The strong antiferro-magnetic interactions within the trinuclear complexes have been observed (J= -266 cm^<-1>, -327 cm^<-1>, -473 cm^<-1> and -245 cm^<-1> for 1a, 1b, 2a and 2b respectively, H= -2JS_1・S_2).
A triangular trinuclear copper (II) complex as model of trinuclear cluster in multi-copper proteins are obtained and the structure of this complex are now in progress.