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A general method for synthesizing optically active, primary, secondary, and tertiary organofluorides was developed. This chiral pool synthesis utilized the skeleton of arabinose to generate diastereomerically pure 2-oxazolidinone-fused aziridines, which underwent ring opening with a fluoride anion. The adducts, polyoxygenated organofluorides, were useful precursors to various fluorinated compounds, such as fluorinated amino acids.

Kijanose is one of the most highly functionalized deoxysugars found in nature and a challenging synthetic target. We found that the ring opening of trisubstituted, 2-oxazolidinone-fused aziridines is regio- and stereoselective, and the azide adduct has the same stereochemistry as that of kijanose after converting the azido to a nitro group. Therefore, both α- and β-methyl l-kijanosides were prepared from ethyl l-lactate in 14% total yield.

In single molecule studies of injection of an electron from a photoexcited dye into a semiconductor nanoparticle or into a film of such nanoparticles, the injection may be into the conduction band or into the band gap, depending on the system. The theory of the process and its return are discussed, in particular when a power law for the waiting time distribution may be expected and what that power might be. To this end a reaction–diffusion equation is set up and solved. When the injection is into the conduction band, a power law is predicted for the return of the electron to the dye cation but not for the injection. After a short time, the law for the waiting time distribution has a power of −1. At short times, before the slower return due to an increasing radius is recognized, the power law is −1/2. When the injection is into the band gap, a −1 power law is predicted for both the injection and the return. Available data are discussed in terms of the theory. A corollary is that single molecule studies for the injection can determine whether the injection is into the band gap or into the conduction band. The theory is tested by single molecule studies of various systems, such as comparing different dye–TiO_2, dye–Al_2O_3, and dye–ZrO_2 systems and comparing specific dye–TiO_2 systems as a function of pH, and dye hole injection into p-type NiO.

The reactivity of a series of nickel(II) hydride, alkyl, and anilide complexes supported by amido diphosphine ligands, including symmetrical [N(o-C6H4PR2)2]− (R = Ph (1a), iPr (1c), Cy (1d)) and unsymmetrical [N(o-C6H4PPh2)(o-C6H4PiPr2)]− (1b), with carbon monoxide is described. Exposure of a benzene solution of [1a–d]NiH to carbon monoxide under ambient conditions leads to reductive elimination of diarylamine to give quantitatively zerovalent nickel dicarbonyl complexes [H·1a–d]Ni(CO)2 (2). Migratory insertion of CO into the Ni-R bonds of [1]NiR in benzene solutions affords Ni(II)-acyl derivatives [1]NiC(O)R (R = Me (3), Et (4), n-hexyl (5), 2-norbornyl (6)). Interestingly, further carbonylation of acyl 3a and 4a generates [RC(O)N(o-C6H4PPh2)2]Ni(CO)2 (R = Me (7a), Et (8a)) as a result of C–N bond-forming reductive elimination whereas no reaction occurs for 3b–c or 4b–c under similar conditions. Carbonylation of the anilide complexes [1]NiNHPh produces carbamoyl [1]Ni[C(O)NHPh] (9) as the final product i...

A modified four-step method has been developed to grow a void-free 3C-SiC film of high quality on Si(100) in a mixed gas of SiH 4 ―C 3 H 8 ―H 2 using low pressure chemical vapor deposition. A diffusion step was added after the carburization step in the traditional three-step method (clean, carburization, growth), and no cooling between each step was required. X-ray photoemission C Is spectra support that the formation of SiC bonds can be greatly improved in the as-carburized Si(100) surface after diffusion at 1350 °C for 300 s. A thick 3C-SiC film of good crystal quality was grown on the as-diffused SiC layer during the growth step, confirmed by both X-ray diffraction and electron diffraction data. Hall effect measurements were used to characterize the electrical properties of SiC films. All the SiC films are n-type. The Hall mobility and carrier concentration of a SiC film of 1.5 μm thick increase from 320 to 395 cm 2 /(V s) and from 1.6 x 10 17 cm ―3 to 2.7 x 10 17 cm ―3 , respectively, when the diffusion step is added.

The theoretical spectra of electroluminescent polymers are studied with time-dependent density functional theories, followed by a systematic scheme with a symmetry restriction to extrapolate the absorption and emission corresponding to infinite chains avoiding periodic boundary conditions. Application to poly(p-phenylene vinylene) (PPV) and the derivatives has been attempted, and the hybrid B3LYP is concluded to be the most suitable functional for computation. The theoretical excitation energies of PPV by B3LYP/6-31G*// B3LYP/STO-3G and B3LYP/6-311G* are 2.107 and 2.027 eV, respectively. With optimization performed by single-excited configuration interaction, the emission spectroscopy can be estimated. By our scheme, the Stokes shift of PPV is calculated to be 0.223 eV, which corresponds to approximately 62 nm in the spectral region.

The syntheses of a series of CpW(CO)2(π-γ-lactonyl) complexes bearing a tethered aldehyde are described. These π-allyl complexes are prepared as either syn- or anti-stereoisomers. Treatment of these dicarbonyl complexes with NOBF4 and NaI in CH3CN effects an intramolecular allylation of the tethered aldehyde, yielding bicyclic α-methylene butyrolactones comprising a homoallylic alcohol. Both syn- and anti-isomers of tungsten-π-allyl compounds produce the same α-methylene butyrolactones. The cyclizations proceed with high diastereoselectivities to give only the cis-fused bicyclic γ-lactones. The preference for cis-fused stereoselection can be rationalized based on a tricyclic transition state mechanism.

Bergman cyclization of the enediynes (Z)-3-hexene-1,5-diyne (1), (Z)-3-heptene-1,5-diyne (2), (Z)-4-octene-2,6-diyne (3), (Z)-1-cyclononene-3,8-diyne (4), (Z)-1-cyclodecene-3,9-diyne (5), and (Z)-1-cycloundecene-3,10-diyne (6) has been studied by density functional methods. The reaction of 1 was first studied using the BP86, BLYP, BPW91, and B3LYP functionals with the 6-311G** basis set and the large ANO basis set for the latter two functionals. The BPW91/6-311G** calculations yielded results comparing well with those of high-level ab initio computations. Thus, BPW91/6-311G** was employed to study the reactions of 2−6. Geometry optimizations and harmonic frequency calculations were applied for every reactant, transition structure, and product; frequency calculations were also carried out for other optimized stationary points. The optimized structure of the conformer of 6 with the lowest energy agrees excellently with the X-ray diffraction crystallographic structure. IRC (intrinsic reaction coordinate) cal...