Photoinduced electron transfer from the charge-transfer excited states of Ru(tpy)(bpy(COOH)₂)$CN^+$, Ru(tpy)(bpy(COOH)₂)$Cl^+$, Ru(tpy)(bpy(COOH)₂)H₂+O², and Ru(tpy)(bqu(COOH)₂)$Cl^+$ to the conduction band of TiO₂ has been studied through photoelectrochemical methods. Ru(tpy)(bpy(COOH)₂)$CN^+$ produced the highest current density and open-circuit photovoltage, whereas Ru(tpy)(bqy(COOH)₂)$Cl^+$ produced the lowest values. A potential barrier was employed to explain the experimental result that the rate of the electron transfer increases with increasing the energy difference between the donor and acceptor. A sensitizer with a high current density yielded a high photovoltage and a high conversion efficiency. The reduction rate of the oxidized sensitizer decreased with the increases in the reduction potential of the sensitizer, resulting in a poor stability of a photoelectrochemical cell.

Ion fragmentations of fatty acids such as stearic acid, palmitic acid, myristic acid, and lauric acid were studied using mass spectrometry and semiempirical calculations. The mass spectra of fatty acids showed the distributions of CH₃(CH₂)$_n^+$ and $[(CH_2)_nCO_2H]^+$ fragment ions. The relative ion abundance distributions of $[(CH_2)_nCO_2H]^+$ showed the local maxima at n=6, 10, and 14. The local maximum phenomena were also found in the mass spectra of methyl stearate but not in those of normal alcohols. These local maxima could be explained not by heats of reaction for fragmentation but by the cyclic structures of the molecular ions. The AM1 semiempirical calculations for fatty acids clearly show that the linear structures are more favorable than the cyclic ones for neutral molecules while the cyclic structures are more favorable than the linear ones for ionic molecules. The distances between carboxyl group and methylene of the cylic structures of ionized fatty acids were calculated. The methylene carbons with n=6, 10, and 14 were closer to the carboxyl group than adjacent ones.

A series of ferrocene-containing chelating bidentate nitrogen ligands (1 & 2) and polyazamacrocycles (3 & 4) were prepared in high yields from the reaction of ferrocenecarboxaldehydes with corresponding diamines under various catalytic and stoichiometric reaction conditions. The stoichiometric condensation to form Schiff bases required the presence of MgSO₄in the reaction mixture as a water-absorbent. Employment of cyclic diamines such as 1,2-diaminocyclohexane and p-phenylenediamine in the reaction with 1,1'-ferrocenedicarboxaldehyde resulted in the formation of polymers in stead of the expected macrocycles. All these compounds were characterized by microanalytical and spectroscopic techniques. In one case, the structure of 3a was confirmed by X-ray crystallography.

A new device to accurately deliver small amount of modifier into supercritical carbon dioxide fluid is described. Carbon dioxide, the most widely used mobile phase in supercritical fluid chromatography, is a relatively non-polar fluid, and hence the addition of small amount of polar modifiers could be necessary to migrate polar solutes. In this work, supercritical CO₂and modifier are delivered from the pump to a 100 μL mixing chamber in which a small magnetic bar is rotating. After passing through the mixing chamber, supercritical CO₂is changed to a new mobile phase with different polarity. The amount of modifier added into supercritical CO₂is measured by an amperometric microsensor, which is prepared from a thin film of perfluorosulfonate ionomer.

Gelation time, gel structure and volatility of by-products during gelation of PZT sol-gel processing were investigated by FT-IR spectroscopy. FT-IR spectroscopic study was performed on PZT gels with the various H₂O contents (1, 2 and 3 mol) and the several types (HNO₃, NH₄OH) and amounts (0.1, 0.2 mol) of catalysts, monitoring temporal (0, 1, 3, 10 weeks, 3 months and 3 years) and thermal (100-700 ℃) changes of FT-IR spectra. The interpretation of temporal change of the spectra revealed two trends. One is under the condition of 1 mol H₂O, 1 mol H₂O+0.1 mol HNO₃, 3 mol H₂O and the other is for 1 mol H₂O+0.1 mol NH₄OH, 2 mol H₂O, 1 mol H₂O+0.2 mol HNO₃. The gel structures and the gelation times for these conditions were discussed in comparison with the reported results of SiO₂, and we suggested the reaction mechanisms for these structural characteristics. Thermal variation of FT-IR spectra was interpreted as the evolution processes of gel by investigating the evaporation of solvent and the decomposition of organic residues.

A number of complexes of transition metal ions with some coumarin derivatives have been prepared and their structures were elucidated with the help of conductometric, photometric and infrared studies. The stability constants of various complexes were determined, in aqueous medium, at different temperatures potentiometrically. The thermodynamic characteristics, ΔG, ΔH and ΔS, were calculated. The electrical behaviour of prepared compounds was followed.

Spherical, submicrometer particles of barium-titanyl oxalate were homogeneously precipitated by thermal decomposition of diethyl oxalate in acidic aqueous solutions. The rates of oxalate ion generations, determined by various combinations of temperature and initial concentration of diethyl oxalate had a very important effect on the particle size distribution. Monosized, bimodal, or broad unimodal powders were obtained under certain combinations of experimental variables.

Reactions of arenealdehyde 2-pyridylhydrazones (1) with thianthrene cation radical ($Th^{+·}$) and tris(2,4-dibromophenyl)aminium hexachloroantimonate ($Ar_3N^{+·}SbCl_6^-$) were investigated. The major product was switched depending on the cation radical being used. That is, s-triazolo[4,3-α]pyridines (2), an intramolecular cyclization product, and 1-(2-pyridyl)-1,2,4-triazoles (3), an intermolecular cycloaddition product, were obtained as a major product when reacted with $Th^{+·}$ and $Ar_3N^{+·}$, respectively in nitrile solvents. The plausible mechanisms are proposed based on both the reduction potentials of $Th^{+·}$ and $Ar_3N^{+·}$ and control experiments.

The preparation and photoluminescence properties of $ZnGa_2O_4$ : Mn phosphor are presented. Under 254 nm excitation $Zn_1-_xMn_xGa_2O_4$ exhibits the green emission band at 506 nm wavelength and maximum intensity where x=0.005. The manganese activated $ZnGa_2O_4$ phosphor prepared by the polymerized complex method shows a remarkable increase in the emission intensity and is smaller particle size than that prepared by conventional method. Also, electron paramagnetic resonance study on $ZnGa_2O_4$ : Mn powders indicates that the increase in emission intensity after firing treatment in mild hydrogen reducing atmosphere is due to the conversion of the higher valent manganese to $Mn^{2+}$.

$LiMn_2O_4$ powders were prepared by burning and subsequent calcination of PEG-metal nitrate precursor. After the burning stage of the precursor, some minor phases such as $Mn_2O_3$ (or $Mn_3O_4$), MnO, and carbonate were formed and single phases of $LiMn_2O_4$ were obtained by further calcinations above 400 ℃. From thermal analysis of the precursor, a violent thermal decomposition, which was indicated by a drastic weight loss accompanied by a sharp and strong exothermic peak, was observed and probably caused by an oxidation-reduction reaction between oxidizer and fuel. The formation of the minor phases could be explained in terms of the burning behavior of the precursor by employing valence concepts of propellant chemistry. The calcined powders were composed of submicron-sized but highly agglomerated particles and showed very broad particle size distribution.

The polysiloxane-bridged dinuclear metallocenes $[(SiMe_2O)_n-SiMe_2(C_5H_4)_2][(C_9H_7)ZrCl_2]_2$ (n=1 (7), 2 (8), 3 (9)) have been generated as a model complex for the immobilized metallocene at silica surface by treating the respective disodium salts of the ligands with 2 equivalents of $(C_9H_7)ZrCl_3$ in THF. All three complexes are characterized by $^1H$ NMR and measurement of metal content through ICP-MS. It turned out that the values of ${\Delta}{\delta}=[{\delta}_d-{\delta}_p]$, the chemical shift difference between the distal $({\delta}_d)$ and proximal $({\delta}_p)$ protons, for the produced dinuclear compounds (0.47 for 7, 0.49 for 8, and 0.5 for 9) were larger than the Δδ value of the known ansa-type complex holding the same ligand as a chelating one, that is just the opposite to the normal trend. In order to compare polymerization behavior of the dinuclear metallocene with the corresponding mononuclear metallocene, (Cp)$(C_9H_7)ZrCl_2$ was separately prepared. To investigate the catalytic properties of the dinuclear complexes and mononuclear metallocenes ethylene polymerization has been conducted in the presence of MMAO. The polymerization results display the typical activity dependence on polymerization temperature for all complexes. The most important feature is that the polymers from the dinuclear metallocenes represent enormously improved molecular weight compared with the polymer from the corresponding mononuclear metallocene. In addition, the influence of the nature of the bridging ligand upon the reactivities of the dinuclear metallocenes has also been observed.

A layered perovskite oxide, $RbLa_2Ti_2NbO_{10}$, was prepared and investigated for proton exchange and intercalation behaviors. Its protonated form, $Hla_2Ti_2NbO_{10}$, exhibits the Bronsted acidity and reacts with organic amines. Polyoxonuclear cation, 4Al_{13}$, was then introduced into the interlayer by refluxing octylamine-intercalated compound with an $Al_{13}$ pillaring solution. These layered oxides were characterized by X-ray diffractometer, thermogravimeter, FT-infrared spectrometer and elemental analyzer. It is observed that the polyoxonuclear cation-pillared material exhibits a bilayer structure and is thermally more stable than organic counterpart at higher temperatures. The surface area of the pillared material annealed at 400 ℃ was the value of 25.1 m²/g.

The preparation and characterization of $Co(dmppz)_2(3,6-dbq)_2$ (dmppz=1,4-dimethylpiperazine; 3,6-dbq=3,6-di-tert-butyl-1,2-quinone) are established. Temperature-dependent magnetic moments (100-400 K), variable-temperature IR, and electronic spectra are presented to show that the title complex exhibits an equilibrium via a catechol to cobalt intramolecular electron transfer. At temperatures below 350 K, the charge distribution of the complex is $Co^Ⅲ(dmppz)_2(3,6-dbsq)(3,6-dbcat)$ (3,6-dbsq=3,6-di-tert-butyl-1,2-semiquinonato; 3,6-dbcat=3,6-di-tert-butylcatecholato) whereas at the temperature beyond 390 K, the complex is predominantly Co^Ⅱ(dmppz)_2(3,6-dbsq)_2$ form in the solid state. At the temperature range of 350-390 K a mixture of Co(Ⅲ) and Co(Ⅱ) redox isomers exist at equilibrium. The transition temperature (Tc) of Co(Ⅲ)/Co(Ⅱ) in solution is approximately 50° lower than that in the solid state. In particular, thermal analysis on solid sample of the complex discloses that the transition for the Co(Ⅲ)/Co(Ⅱ) is accompanied by the change in heat content of 12.30 kcal/mol.

Four steroids including two novel compounds have been isolated from a sponge of the genus Tethya. All of the compounds possess a 5α,8α-epidioxy functionality as a common structural feature. Two new steroids, 1 and 2, possess a cyclopropyl ring at C-24(26) of the side chain. The structures of these compounds have been determined by combined spectroscopic methods.

The structure and conformational behavior of the oxyanions of calix[4]arene have been studied by the NMR spectrum. The structure of the oxyanions of calix[4]arene was completely dependent upon the counter cation in present. All of the anions derived from in the presence of NaH and KH appear to exist as a cone conformation, whereas those produced with lithium cation such as n-butyllithium and LiOD show a more varied conformational behavior. The mono and tetraanions with lithium cation exist as a cone conformation, the trianions appear to exist as a partial cone conformation, and the dianions appear to disproportionate to the mono and trianions. The conformational stability decreases in the order of $Li^+$ oxyanion > $Na^+$ oxyanion > $K^+$ oxyanion.

Pure titanium dioxide $(TiO_2)$ films were prepared by pulsed laser deposition on a single crystal Si(100) substrate. We have investigated the growth of crystalline titanium dioxide films with respect to substrate temperature and ambient oxygen pressure. The structural properties of the films were analyzed by X-ray diffraction. We found that the anatase as well as the rutile phases could be formed from the original rutile phase of the target $TiO_2$. At 0.75 torr of ambient oxygen pressure, the structure of $TiO_2$ film was amorphous at room temperature, anatase between 300 and 600 ℃, a mixture of anatase and rutile between 700 and 800 ℃, and only rutile at 900 ℃ and above. However, at a low ambient oxygen pressure, the rutile phase became dominant; the only rutile phase was obtained at the ambient oxygen pressure of 0.01 torr and the substrate temperature of 800 ℃. Therefore, the film structures were largely influenced by substrate temperature and ambient oxygen pressure.

Introduction of an alkyl substituent at the $C_{4\beta}$ position of antimalarial trioxanes has caused them to become more active in their antimalarial activity. We have designed a structurally simple 4β-phenyl substituted trioxane (3) as an active antimalarial since it can form a more stable carbon radical when reacting with ferrous bromide. The trioxane 3 has been prepared along with the corresponding isomer 4 according to the previously reported procedure. The synthesized trioxanes 3 and 4 were finally separated by using HPLC and assigned their stereochemistry by spectroscopy and X-ray crystallography. Their antimalarial activities were surprisingly low. The low activity was then rationalized based on the product distribution of the ferrous ion induced reaction of these trioxanes. These trioxanes with ferrous bromide did not produce any detectable amount of the corresponding $C_4$-hydroxylated product, consistent with the fact that neither $C_{4\beta}$-phenyl substituted nor $C_{4\alpha}$-phenyl substituted trioxane has any antimalarial activity. It implies that a $C_4$ substituent of antimalarial trioxanes has to stabilize an adjacent carbon-centered radical in a specific stability range in order to show a good antimalarial activity. This study, combined with related studies, could help develop more potent antimalarial trioxanes.

Acetolactate synthase was purified from Escherichia coli MF2000/pTATX containing Arabidopsis thaliana acetolactate synthase gene. Purification steps included DEAE cellulose ion exchange column chromatography, phenyl sepharose hydrophobic column chromatography, hydroxylapatite affinity column chromatography, and Mono-Q HPLC. Molecular weight was estimated to be ∼65 KDa and purification fold was 109 times. The enzyme showed a pH optimum of 7 and the $K_M$ value was 5.9 mM. The purified enzyme was not inhibited by any of the end products, valine, leucine, and isoleucine.

The new unsymmetric $N_6$ ligand 1-amino-13-(2-pyridyl)-3,6,9,12-tetraazatridecane (aptatd) containing one pyridyl group has been synthesized and characterized by EA, IR, and NMR. Its proton association constants $(log K_H^n)$ and stability constants $(log K_{ML})$ for Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ), and Zn(Ⅱ) ions were determined at 298.1 K and ionic strength 0.100 mol $dm^{-3}$ (KNO₃) in aqueous solution by potentiometry: log $K_H^1$=8.80, log $K_H^2$=8.49, log $K_H^3$=6.84, log $K_H^4$=4.17, log $K_H^5$=3.47; log $K_{ML}(Co^{2+})$=18.00, log $K_{ML}(Ni^{2+})$=21.31, log $K_{ML}(Cu^{2+})$=23.62, log $K_{ML}(Zn^{2+})$=15.60. The X-ray structure of its nickel(Ⅱ) complex [Ni(aptatd)]$(ClO_4)_2$ are reported: orthorhombic space group Pbca, a=15.715(1) Å, b=14.280(2) Å, c=19.443(2) Å, V=4363.4 (9) ų with Z=8. The geometry around nickel is a distorted octahedron with the pyridine nitrogen atom being cis to the nitrogen atom of the terminal primary amine.

Gas-phase phenyl group migration within the protonated ketones has been studied MO theoretically using the AM1 method. The initial state structure shows relatively strong resonance delocalization of positive charge into the nonmigrating (Y) ring, while the ring migration (Z-ring) is nearly complete in the transition state. These results are reflected in the large $p^+_Z$ (<0) and $p^+_$Y (>0) values and in the predominant contribution of resonance (r) over inductive (field, f) effect, r/f ranging from 1.3 ($p^+_r$) to 1.5 ($p^+_z$). The cross-interaction constant $p_{YZ}$ is vanishingly small ($p_{YZ}$=0.03) which is in contrast to the larger magnitudes for benzilic ($p_{YZ}$=-0.48) and azibenzil ($p_{YZ}$=-0.53) rearrangement processes. The relationship found between the extent of resonance contribution in the initial state and the magnitude of $p_{YZ}$ provides strong support for the proportionality between the magnitude of $p_{YZ}$ and the change in the intensity of interaction, ${\Delta}I^{\cdot}_{YZ}$, in the activation process.