Anisotropic strain and Jahn-Teller effect of chiral complexes and metal oxides

For about a decade, we have systematically investigated thermally-accessible lattice strain and local pseudo Jahn-Teller distortion of [CuL2]3[M(CN)6]2·4H2O (L = (1R, 2R)-cyclohexanediamine; M = Cr, Co, and Fe). In mononuclear Cu(II) complexes, (pseudo) Jahn-Teller effect plays an important role in flexible distortion of crystal structures especially Cu(II) coordination environment. Beside Jahn-Teller distortion, we have dealt with some factors for example, metal substitution as bimetallic assemblies, chirality of ligands, and H/D isotope effect to vary intermolecular interaction and crystal packing. According to the course work using variable temperature PXRD, we have found that anisotropy of crystal strain distortion did not corporate with Jahn-Teller distortion around local coordination environment because of the discrepancy of the crystallographic axes and molecular alignment. In order to elucidate the anisotropic control of lattice strain and Jahn-Teller distortion closely, we have employed transition metal oxide with orthogonal or layered structures to prepare composite materials with the chiral metal complexes for discussion of thermally-accessible PXRD changes and IR shift due to adsorption. At first, we have employed chiral one-dimensional zig-zag Cu-Cr bimetallic assemblies and their oxides prepared by burining. Based on variable temperature XRD patterns, a linear correlation (lnK = a/T + b) of K (=d(T)-d(0)/d(T)) values, where d(T) and d(0) are spacing of lattice plane (d = nλ/(2sinθ)) at T K and 0 K (extrapolated), respectively, and its deviation from ideal correlation indicates degree of anisotropic lattice distortion of the composite materials. For example, we could observe LiMnO2, typical material of lithium ion battery, was enhanced anisotropic lattice strain along the b axis or the (011) plane added by [CuL2(H2O)2](NO3)2 complexes. Which may prevent from breaking down regular crystal structures during charge-discharge of secondary battery.

Observation of electron transfer associated with enzymatic process by muSR

We propose muSR experiments on trypsin-BPTI complex to visualize the electron and proton transfer processes occurring in the catalytic reaction of the trypsin. The mechanism of an inhibitory effect of the BPTI is interpreted that the reaction products of BPTI remain at a part of the structure and the reverse reaction reforms the stable trypsin–BPTI complex, which has been confirmed by neutron diffraction experiment of the trypsin-BPTI complex [1]. However, it never sees the real image of the proton and electron transfer processes directly. According to the model provided by the results of neutron diffraction experiments, the proton and electron transfer processes are continuously occurring in a crystal of trypsin-BPTI complex and the process induces the local magnetic field. The slow muon is very adequate because the position, where mu+ is captured, is absolutely negatively charged oxyanion hole close to the reaction center of Trypsin. The distance between the oxyanion hole and the active peptide bond is about 10Å. When the turn over time of the catalytic reactions is assumed to be 10msec or so, the induced magnetic field would be estimated as 0.2 micro-T. In order to check the effectiveness of the measurement of the μSR experiments on trypsin-BPTI complex, another measurement of the muSR experiments on the trypsin- MIP complex is adequate [2]. Here, MIP is a kind of the trypsin inhibitor, which completely stops the catalytic reaction of trypsin. In the trypsin-MIP complex, no electron and proton transfers at all in the active site of trypsin and captured mu+ at the oxyanion hole would never be sensitive to the induced magnetic field [3].