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A practically modified ATR configuration has been proposed for in situ electrochemical surface-enhanced IR absorption spectroscopy (SEIRAS) by sandwiching an ultrathin water interlayer between a hemicylindrical ZnSe prism and a Si wafer as an integrated window. This new ATR optics significantly enhances the throughput of an effective IR beam across the ZnSe/gap/Si/metal film, enabling high-quality spectral fingerprints down to 700 [cm.sup.-1] to be readily detected at larger incidence angles without compromising the electrochemical feasibility and stability of metallic films deposited on Si. The advantages of this modified ATR-SEIRAS have been initially applied to explore two selected systems: wide-ranged in situ ATR-SEIRA spectra provided strong evidence in support of the formate intermediate pathway for methanol electrooxidation at the Pt electrode in an acid solution; in addition, new spectral fingerprints revealed comprehensive orientational information about of the p-nitrobenzoate species at Pt electrode as a result of the dissociative adsorption of p-nitrobenzoic acid molecules from an acid solution.

The femtosecond time-resolved studies were performed on rhodamine 700 in acetone solution and on oxazine 750 in acetone and formamide solutions at different temperatures using fluorescence depletion spectroscopy. The study suggests a new method to study the molecular interaction in liquids.

A detailed investigation of the complex potential energy surface for the reaction of singlet methylene (CH2) with Nitrous oxide (N2O) using B3LYP/6-31G(d,p) and single point QCISD(T)/6-311G(d,p) methods is presented. This work can assist experiments to identify the products of the CH2+NO2 reaction.

Research has been conducted on the aliphatic carboxylic group. The reduction of this group to the methyl group HSiEt (sub)3 in the presence of catalytic amounts of B(C (sub)6 F (sub)5) (sub)3 has been carried out and the results are presented.

Research describes the synthesis of 2,3,4,-trisubstituted 1H-pyrroles starting from 1-protected 3,4-bis-(trimethylsilyl)-1H-pyrroles. The reactions proceed with an alpha-lithiation and quenching by an electrophile followed by a regiospecific ipso-iodination via beta-effect of a trimethylsilyl group and deprotection of the 1-substituent.

The synthesis of 1-substituted and 1-unsubstituted 3,4-disubstituted 1H-pyrroles is performed in a stepwise and repeated iodination and palladium-catalyzed cross-coupling reaction. Data indicate that the p-toluenesulfonyl group is the best protection group in the synthetic process of several parent 3,4-disubstituted 1H-pyrroles.

The existence of 1-tert-butoxycarbonyl-3,4-didehydro-1H-pyrrole (4) as a reactive and highly strained cyclic cumulene at room temperature has been verified by trapping reaction with benzene, furan and acrylonitrile. The experiment used 3,4-bis(trimethylsilyl)-1'H'-pyrerole to generate 4. The experiment is expected to lead to the future generation of 3,4-didehydrofuran, the group's last and most difficult member to synthesize.

A nonactivatable form of plasminogen is symbolized by the unusual homology of lipoprotein(a), Lp(a), with plasminogen, and leads to the stimulation of competitive inhibition of fibrinolysis. The process reveals inconsistencies and the theory remains hypothetical. Experiments reveal theories contradictory to assumptions on the mediation of the atherogenicity of Lp(a) by another mechanism. Possible prevention of plasminogen activation on the endothelium is also discussed.

A study was done to investigate the kinetics of fibrin fragment E-2 promotion on the activation of plasminogen by pro-urokinase (pro-UK). Interference by urokinase (UK) production during reaction was averted by using a recombinant plasmin-resistant mutant pro-UK. E-2 fragment was ranged against a native form of Glu-plasminogen and the results were compared with the results obtained from Lys-plasminogen. Results showed that fibrin fragment E-2 enhanced plasminogen activation by the recombinant pro-UK by more than 450-fold which was almost similar to that of UK.

The Langmuir-Blodgett technique without any extra hydrophobic pretreatment or functionalization is utilized to produce well-defined periodic mesostructures of hydrophilic ultrathin Te nanowires with aspect ratios of at least [10.sup.4]. The method could also be extended for fabrication of other mesostructured assemblies of ultrathin nanowires or nanotubes.

The synthesis, structural characterization, and properties of a group of ferrocene-containing poly(phenylacetylene)s (PPAs) with different alkyl spacers are reported. The magnetic nanocomposites obtained by the attachment of magnetic nanoparticles onto carbon nanotubes (CNTs) might find use in an array of high-tech applications.

A direct evolution method was developed to evaluate mutation metabolism of yeast pyruvate decarboxylase 1 (Pdc1) variants. The results obtained from mutations of 5LS30 variant can be used to analyze activity in crude lysates and other directed evolution projects.

The solute-solvent intermolecular photoinduced transfer (ET) reaction which account for the drastic fluorescence quenching behaviors of oxazine 750 (OX750) chromophore in protic alcoholic solvents is reported.

The phase evolution, texture behavior, and surface chemistry of nanostructured scandium (hydrous) oxides hydrothermally synthesized under various basic conditions are presented. An olation-oxidation process based on a dissolution/recrystallization mechansim is proposed to explain the formation of various ScOOH polymorphs and Sc(OH)3 with different shapes.

Femtosecond time-resolved stimulated emission pumping flourescence depletion spectroscopy (FS TR SEP FD) is used to study the intra- and intermolecular relaxations of dye molecules after the excitation to the high-lying excited states by a femtosecond laser pulse. The more favorable the energy transfer between the solute and solvent molecules is, if higher the states density of the solvent.

A new palladium-catalyzed domino approach for the synthesis of attractive spirocyclic indolines and dihydrobenzofurans was developed. The reaction proceeds through a sequential intramolecular Heck spirocyclization, remote C-H activation, and diazocarbonyl carbene insertion. Various spiroindolines and spirodihydrobenzofurans containing two quartenary carbon stereocenters were readily obtained in good to excellent yields. A preliminary study of asymmetric spirocyclization using chiral monophosphoramidite as a ligand was also conducted, enabling access to highly valuable chiral spiroindolines with up to 80% ee. [ABSTRACT FROM AUTHOR]

The introduction of a C═O, C═C, C═S, or C═N bond has emerged as an effective strategy for carbocycle synthesis. A computational mechanistic study of Rh(III)-catalyzed coupling of alkynes with enaminones, sulfoxonium ylides, or α-carbonyl-nitrones was carried out. Our results uncover the roles of dual directing groups in the three substrates and confirm that the ketone acts as the role of the directing group while the C═C, C═N, or C═S bond serves as the cyclization site. By comparing the coordination of the ketone versus the C═C, C═N, or C═S bond, as well as the chemoselectivity concerning the six-versus five-membered formation, a competition relationship is revealed within the dual directing groups. Furthermore, after the alkyne insertion, instead of the originally proposed direct reductive elimination mechanism, the ketone enolization is found to be essential prior to the reductive elimination. The following C(sp2)--C(sp2) reductive elimination is more favorable than the C(sp3)--C(sp2) formation, which can be explained by the aromaticity difference in the corresponding transition states. The substituent effect on controlling the selectivity was also discussed. [ABSTRACT FROM AUTHOR]

Bronze-phase vanadium dioxide VO2(B) is notable as a promising cathode material for high-capacity Li ion batteries. While various forms of VO2(B) nanostructures have been experimentally investigated, a comprehensive theoretical understanding of the lithium storage mechanism is still lacking. In this research, we examine the redox mechanism, structural evolution, electronic characteristics, and the kinetics of Li ion diffusion in VO2(B) by first-principles calculations. The impact of the surface environment on the Li ion insertion properties is also investigated. Our study demonstrates that, although VO2(B) is capable of incorporating one Li per formula unit from a thermodynamic perspective, its actual capacity can be much less due to kinetic factors. Energy barrier calculations reveal a pronounced compositional dependence of Li diffusion in bulk VO2(B): the b axis tunnels, which account for the excellent Li diffusivity at low Li content, become blocked when Li concentration goes up. The equilibrium surfaces are predicted to be oxygen-rich in an oxidizing atmosphere, which would lead to a steep gradient of Li concentration near the surfaces and further impede Li intercalation into the bulk. Yet, these limitations can be circumvented by facilitating the diffusion of Li in the c direction that is still feasible at high Li content and stabilizing the stoichiometric terminations of (0 0 1) and (1 1 0) facets, which can alleviate the load of excess Li near the surfaces. Our theoretical insights can provide a rationale for the different experimental values of specific capacity in the literature and inspire new strategies to optimize the electrochemical performance of VO2(B). [ABSTRACT FROM AUTHOR]

A Cu(OAc)2-catalyzed domino tricyclization between naphthalene-1,8-diamine and 2-(phenylethynyl)benzaldehyde is described, enabling aerobic oxidative dehydrogenation coupling to access heptacyclic quinolizino[3,4,5,6-kla]perimidines. In this reaction, the formation of three new rings and four new bonds was achieved in a functional-group-compatible fashion, allowing a facile method toward fused aza-heterocycles containing both quinolizine and perimidine moieties. [ABSTRACT FROM AUTHOR]

The mechanism of redox-neutral Rh(III)-catalyzed coupling reactions of arylnitrones with alkynes was investigated by density functional theory (DFT) calculations. The free energy profiles associated with the catalytic cycle, involving C(sp²)-H activation, insertion of alkyne, transfer of O atom, cyclization and protodemetalation, are presented and analyzed. An overwhelming preference for alkyne insertion into Rh-C over Rh-O is observed among all pathways, and the most favorable route is determined. The pivalate-assisted C-H activation step is turnover-limiting, and the cyclization step determines the diastereoselectivity of the reaction, with the stereoselectivity arising mainly from the difference of noncovalent interactions in key transition states. The detailed mechanism of O atom transfer, RhIII-RhI-RhIII versus RhIII-RhV-RhIII cycle, is discussed. [ABSTRACT FROM AUTHOR]

Four metal-organic coordination compounds Zn2(bcbp)Cl4 (1), Zn(bcbp)(PO3F) (2), [CdCl(Hbcbp)(bcbp)]·(ClO4)2 (3), and [Cd2(bcbp)4]·(ClO4)·F3 (4) (H2bcbp·2PF6 = 1,1′-bis(4-carboxyphenyl)-(4,4′-bipyridinium) hexafluorophosphate) have been synthesized via a solvothermal method and structurally characterized. Compound 1 is a 1D coordination polymer, while compound 2 shows a 2D + 2D → 3D inclined polycatenation structure. In the case of compound 3, due to the capped chlorine atoms and uncoordinated carboxyl of bcbp ligand, it exhibits a 1D T-shaped coordination configuration. Compound 4 is an unprecedented 13-fold interpenetrating structure with huge diamondoid frameworks. Because of the presence of electron-deficient bipyridinium moieties, the photochromic behaviors of these compounds have also been studied. Interestingly, only compounds 1-3 exhibit color changes under light irradiation. The impact of these anions on the photochromic process is discussed. [ABSTRACT FROM AUTHOR]

Host-guest encapsulation of electron-rich naphthalene molecules into a weakly emissive porous metal-organic framework based on π-electron-deficient (π-acidic) naphthalene diimide tectons leads to orange-emissive crystals, which can be used to sense strongly basic organic amines in a fast response, high photostability, and tunable sensitivity. Moreover, such host-guest inclusion crystals are also a good photochromic probe for the detection of weakly basic N-methyl-2-pyrrolidone and N,N-dimethylformamide molecules. [ABSTRACT FROM AUTHOR]

The development of an efficient andpractical method for the preparationof alkyl trifluoromethyl ethers is urgently demanding. The silver-mediatedoxidative O-trifluoromethylation of primary, secondary,and tertiary alcohols with TMSCF3under mild reaction conditionsis established to provide a novel approach to a broad range of alkyltrifluoromethyl ethers. Further, this method is applied to the late-stage O-trifluoromethylation of complex natural products and prescribedpharmaceutical agents. [ABSTRACT FROM AUTHOR]