The EPR spectra of Cu-or Zr-doped BaTiO3 ceramics exhibited absorption signals with g∥=2.380 and g⊥=2.063 which are assigned to Ba1+(Ba2+ + e'→Ba1+) ion reduced by an electron that was produced from the oxygen vacancy (VO..). The intensity of these signals decreased as the temperature increased indicating that Ba1+ was changed to Ba2+ as the temperature increased. These ceramics also showed the EPR signal with g=1.997 around TC which arises from ionized Ba-vacancies, VBa'(VBa + e'→VBa'. In the orthorhombic and tetragonal phase region g=1.997 signal was not seen. The electrons generating from the oxidation of Ba1+ and ionized Ba-vacancies may contribute to a space charge which is responsible for a dielectric relaxation of these samples.

Ornidazole, C7H10ClN3O3, crystallizes in the triclinic, space group P1^, with a=13.605(2), b=14.054(1), c=8.913(5) Å, α=71.59(2), β=78.73(2), γ=64.86(1)°, μ=3.26 cm-1, Dc=1.499 g/cm3, Dm=1.497g/cm3, F(000)=684, and z=6. Intensities for 2693 unique reflections were measured on a CAD4 diffractometer with graphite-monochromated Mo-Kα radiation. The structure was solved by direct method and refined by block-diagonal least squares to a final R of 0.081 (Rw=0.047) for 1952 reflections with Fo>3σ (Fo). The asymmetric unit contains three independent molecules of the title compound. The bond lengths and bond angles are comparable with the values found in the other nitro-substituted compounds. The nitro groups are rotated (6.9°, 6.6°, 2.6° for the three independent molecule, respectively) about the C-N axes from the imidazole planes. The crystal structures are linked by two intermolecular hydrogen bonds of O-H---N type and one intermolecular hydrogen bond of O-H---O type.

The parameters for an empirical net atomic charge calculation method, Modified Partial Equalization of Orbital Electronegativity (MPEOE), were determined for the atoms in organosilicon compounds and zeolites. For the organosilicon family, the empirical parameters were determined by introducing both experimental and ab initio observables as constraints, these are the experimental and ab initio dipole moments, and the ab initio electrostatic potential of the organosilicon molecules. The Mulliken population was also introduced though it is not a quantum mechanical observable. For the parameter optimization of the atoms in the aluminosilicates, the dipole moments and the electrostatic potentials which calculated from the 6-31G** ab initio wave function were used as constraints. The empirically calculated atomic charges of the organosilicons could reproduce both the experimental and the ab inito dipole moments well. The empirical atomic charges of the aluminosilicates could reproduce the ab initio electrostatic potentials well also.

Four crystal structures of M3-A (M3Na9-xHx-A, M=Rb or K and x=1 or 0), Rb3Na8H-A(a=12.228(1) Å and R1=0.046), Rb3Na9-A (a=12.258(3) Å and R1=0.058), K3Na8H-A (a=12.257(3) Å and R1=0.048) and K3Na9-A (a=12.257(3) Å and R1=0.052), have been determined by single crystal x-ray diffraction technique in the cubic space group Pm3^m at 21 ℃. In all structures, each unit cell contained three M+ ions all located at one crystallographically distinct position on 8-rings. Rb+ ions are 3.12 and 3.21 Å away respectively from O(1) and O(2) oxygens, about 0.40 Å away from the centers of the 8-rings, and K+ ions are 2.87 and 2.81 Å apart from the corresponding oxygens. These distances are the shortest ones among those previously found for the corresoponding ones. Eight 6-rings per unit cell are occupied by eight Na+ ions, each with a distance of 2.31 Å to three O(3) oxygens. The twelfth cation per unit cell is found as Na+ opposite 4-ring in the large cavities of M3Na9-A and assumed to be H+ for M3Na8H-A. With these noble non-framework cationic arrangements, larger M+ ions preferably on all larger 8-rings and the compact Na+ ions on all 6-rings, the bond angles in the 8-rings of M3-A, 145.1 and 161.0 respectively for (Si,Al)-O(1)-(Si,Al) and (Si,Al)-O(2)-(Si,Al), turned out to be remarkably stable and smaller, by more than 12 to 17°, than the corresponding angles found in the crystal structures of zeolites A with high concentration of M+ ions. It is to achieve these remarkably relaxed 8-rings, the main windows for the passage of gas molecules, with simultaneously maximized cavity volumes that M3-A have been selected as one of the efficient zeolite A systems for gas encapsulation.

The electronic band structure and electrical properties of KMo4O6 containing chains of condensed molybdenum octahedra are analyzed by means of the extended Hu&ckel tight-binding method. KMo4O6 has partially filled bands of 1D as well as 3D character. They also exhibit the anisotropic band dispersions with bandwidths much larger along the c* axis than along the directions perpendicular to it. Thus, conduction electrons are essentially delocalized along the c* direction (i.e., the chain of condensed molybdenum octahedra) in the solid. The 1D band of two partially filled d-block bands leads to Fermi surface nesting with the wave vector q=0.3c*. The CDW instability due to this nesting is expected to cause the phase transition associated with the resistivity anomaly at low temperature. The characteristics of metallic behavior in the crystallographic ab plane are explained on the basis of the unnested 2D Fermi surfaces.

A series of solid solutions in the Ca2AlxFe2-xO5 (x=0.00, 0.50, 0.66, 1.00 and 1.34) system with brownmillerite structure has been synthesized at 1100 ℃ under an atmospheric air pressure. The solid solutions are analysed by powder x-ray diffraction analysis, Mohr salt titration, thermal analysis, and Mossbauer spectroscopic analysis. The x-ray diffraction analysis assigns the compositions of x=0.00 and 0.50 to the space group Pcmn and those of x=0.66, 1.00, and 1.34 to the Ibm2. Mo&ssbauer spectra have shown the coordination state and disordering of Al3+ and Fe3+ ions. The substituting preference of Al3+ ions for the tetrahedral site decreases with increasing x value. Magnetic susceptibility of the system has been measured in the temperature range of 5 K to 900 K. The solid solutions of the compositions of x=0.00, 0.50 and 0.66 have shown a thermal hysteresis and the thermoremanent magnetization gap decreases with increasing x value in the above systems. However the compositions of x=1.00 and 1.34 do not show the hysteresis. The exchange integral is calculated from Fe3+ ion occupancy ratio. The integral decreases with x value and thus the magnetic transition temperature decreases with the increasing x value.

Hydrolysis of p-nitrophenyl acetate (PNPA) and p-nitrophenyldiphenyl phosphate (PNPDPP) by N-chloro compounds in micellar solution were studied. N,N'-dichloroisocyanuric acid sodium salt (DCI) in cetyltrimethylammonium chloride (CTACl) micellar solution gave pseudo first-order kinetics. But, DCI in cetyltrimethylammonium bromide (CTABr) micellar solution showed typical series first-order kinetics - fast hydrolysis of the esters and concomitant slow decay of the hydrolyzed product, p-nitrophenolate. The hydrolysis rate was decreased as the hydrophobicity of N-chloro compounds was increased, which is the opposite trend to the usual bimolecular micellar reaction. This curious behavior of the N-chloro compounds in the catalytic hydrolysis of PNPA and PNPDPP in a cationic micellar system can be best explained by participation of counter ions of the surfactants during hydrolysis.

A generic force field approach has been applied to geometry optimization of penam and cephem crystals. The crystalline state energy and force evaluation with the universal force field (MMFF: Merck Molecular Force Field) results in good agreements with the crystallographic data. Bond lengths are usually correct to within 0.02 Å and bond angles usually to within 2.5°. The conformation of the β-lactam bicyclic rings in the crystal environment is also well reproduced. The results thus demonstrate the applicability of MMFF to modeling of newer molecular constructs in condensed phase.

In order to ease the treatment of anisotropic potential when developing the variational RRKM theory, we applied Fano-Racah's recoupling theory to the multipole-multipole interaction, resulting in the great simplification of the anisotropic potentials. The treatment appears as a generalization of Keesom transformation in case of dipole-dipole interaction and provides us with great insights to the characteristics of tensorial interactions in the multipole-multipole interaction system.

Generalized Multichannel Quantum Defect theory (MQDT) was implemented to the vibrational predissociation of triatomic van der Waals molecules in the previous paper [Bull. Korean Chem. Soc, 12, 228 (1991)]. Implementation was limited to the calculation of the scattering matrix. It is now extended to the calculation of the predissociation spectra and the final rotational distribution of the photofragment. The comparison of the results with those obtained by other methods, such as Golden-rule type calculation, infinite order sudden approximation (IOS), and close-coupling method, shows that the implementation is successful despite the fact that transition dipole moments show more energy dependence than other quantum defect parameters. Examination of the short-range channel basis functions shows that they resemble angle-like functions and provide the validity of the IOS approximation. Besides the validity of the latter, only a few angles are found to play the major role in photodissociation. In addition to the implementation of MQDT, more progress in MQDT itself is made and reported here.

The heme assignment of the 1H NMR spectrum of cytochrome c3 of Desulfovibrio vulgaris Hildenborough within the X-ray structure were fully cross established according to their redox potential. The major reduction of the heme turned out to take place in the order of hemes Ⅳ,Ⅰ,Ⅱ and Ⅲ(the heme numbers indicating the order of bonding to the primary sequence). This assignment can provide the physicochemical basis for the elucidation of electron transfer of this protein.

A trace amount of 4-biphenylcarboxylate having a pre-twisted biphenyl moiety was attached to a poly(methyl methacrylate) side chain and the fluorescence properties of the chromophore were investigated in various solvents such as ethyl acetate and butyl chloride. At room temperature, the polymer exhibited a distinct red shift of the short wavelength emission (325 nm) and an enhanced emission intensity around 430 nm upon excitation at the absorption red edge. The temperature dependence of the intensity ratio (R) of the 325 nm emission to the 430 nm emission was observed when exciting at the red edge over the temperature range between -20 and 60 ℃. However, the temperature dependence was not observed when exciting at the shorter wavelength. The Arrhenius plot of the R value shows the activation energy of 6.0 kJ/mol which is in good agreement with the energy required for the twist of the biphenyl moiety. Together with the results of red edge excitation effects it was concluded that the pre-twisted geometry of the biphenyl moiety is preserved by the restriction of the polymer chain to facilitate the formation of the twisted intramolecular charge transfer (TICT) state upon excitation.

A new chiral stationary phase (CSP 2) derived from cyclohexylamide of (S)-naproxen has been prepared. CSP 2 has shown greater enantioselectivities for the two enantiomers of N-(3,5-dinitrobenzoyl)-a-amino esters and amides than the CSP derived from 3,5-dimethylanilide of (S)-naproxen (CSP 1) as expected from the reciprocity conception of chiral recognition. However, CSP 2 has been found to be worse than CSP 1 in resolving N-(3,5-dinitrobenzoyl)-a-arylalkylamines, supporting the previously proposed chiral recognition mechanism which utilizes the 3,5-dimethylphenyl group of CSP 1 as an alternative π-basic interaction site. In addition, CSP 2 has been found to be reasonably good in resolving the two enantiomers of a variety of other π-acidic racemates.

New diamineplatinum(Ⅱ) complexes of cyclohexylidenemalonate (chm) ligand, A2Pt(OOC)2C=C(CH2)4CH2 (1, A2=ethylenediamine (en); 2, A2=propylenediamine (pn); 3, A=NH3; 4, A=isopropylamine (ipa)) have been prepared. Their oxidation with H2O2 has led to the corresponding dihydroxoplatinum(Ⅳ) complexes: cis, cis, trans-A2Pt((OOC)2C=C(CH2)4CH2)(OH)2 (5, A2=en; 6, A2=pn; 7, A=NH3; 8, A=ipa). The title complexes have been characterized by means of various spectroscopies and X-ray crystallography. 5 crystallizes in the monoclinic space group P21/a (Z=4) with a=12.098(7) Å, b=9.552(2) Å, c=16.258(4) Å, β=98.03(5)° and V=1860(1) Å3. The structure was refined to R=0.074. The local geometry around platinum atom is approximately octahedral with each hydroxide group in trans position. These platinum complexes are stable in aqueous solution. Pt(Ⅳ) complexes are readily reduced to the corresponding Pt(Ⅱ) complexes by ascorbic acid.

2-Epideoxymannojirimycin 1 and (2R,3R,4R,5R)-3,4,5-trihydroxypipecolic acid 2 were prepared starting from D-glucosamic acid as a chiral educt. Key transformations were selective removal of the terminal isopropylidene group and intramolecular cyclization by SN2 reaction.

No fluorescence was observed from 1-aryl-4-(pentamethyldisilanyl)buta-1,3-diynes except 1-(1-naphthyl)-4-(pentamethyldisilanyl)buta-1,3-diyne. Irradiation of 1-aryl-4-(pentamethyldisilanyl)buta-1,3-diynes (1) with methanol gives photoaddition products in relatively low yields compared to arylethynyldisilanes which show dual fluorescence. Irradiation of 1 with acetone yields site specific and regioselective 1:1 photoadducts through silacyclopropene intermediates. The triplet excited state of the silacyclopropene reacts with acetone to give addition photoproducts and the triplet energy of the silacyclopropenes lies around 260-286 kJ/mol.