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The effects of anchoring groups on electron injection from adsorbate to nanocrystalline thin films were investigated by comparisons injection kinetics through carboxylate versus phosphonate groups to Ti[O.sub.2] and Sn[O.sub.2]. The anchoring groups were shown to have negligible effects on the energetics of relevant orbitals in the Re complexes.

The dependence of Re(L(sub p))(CO)3Cl (or ReClP) [Lp = 2,2'-bipyridine-4,4'-bis-CH2PO(OH)2] and Re(LA)(CO)3Cl (or ReClA) [L(sub A)=2,2'-bipyridine-4,4'-bis-CH2COOH] sensitized TiO2 and ReClP sensitized SnO2 nanocrystalline thin films is examined. Results suggests that the observed pH-dependent electron transfer rate can be qualitatively accounted for by considering the change of density of electron-accepting states caused by the pH-dependent conduction band edge position.

A convenient route is developed for preparing various charged tetracyclic isoquinolizinium hexafluorostilbates by using AgSb[F.sub.6]/AuCl(P[Ph.sub.3]) for the intramolecular addition of amine to alkyne. The process is tolerant of a variety of functional groups and has broadened the diversity of substrates with the use of 8-substituted tetracyclic isoquinolizinium salts.

A synthesis method is described by using chlorotrimethylsilane as the activator to brominates the Ni(II) complex of the [beta]-alanine SchiffEs base [[beta]-AlaNi(II)PABA] and it is developed to prepare [beta]-amino acids. The procedure has involved a Suzuki coupling reaction between boric acids and bromoenone and this is the first report on the application of the Ni(II) complex [[beta]-AlaNi(II)PABA] for producing [alpha]-aryl-/heteroaryl-substituted [beta]-amino acids.

The design and synthesis of a novel phosphodiester receptor 1-(2-guanidinoethyl)-4-(2-hdyroxyethyl)1-1,4,7-triazacyclononane hydrochloride and the studies of its DNA cleavage activity is reported. Kinetic data of DNA cleavage promoted by 1-(2-guanidinoethyl)-4-(2-hdyroxyethyl)1-1,4,7-triazacyclononane hydrochloride fit to a Michaelis-Menten-type equation with [K.sub.max] of 0.160 [h.sup.-1] giving [10.sup.7]-fold rate acceleration over uncatalyzed DNA.

Smad3 is phosphorylated by ERK MAP kinase upon EGF treatment. The ERK phosphorylation sites to Ser 207, Ser 203, and Thr 178 in Smad3 is mapped and it is shown that mutation of the ERK phosphorylation sites increases the ability of Smad3 to stimulate a Smad target gene, suggesting that ERK phosphorylation inhibits Smad3 activity.

Potential step measurement is performed on single beads of spherical nickel hydroxide to determine the proton diffusion coefficient (D) and concentration of the effective proton vacancies (C). The semi-infinite diffusion equation for the initial stage and the finite diffusion equation for the long-term of the current response to potential step are used for deducing the D and C values.

Multisegment Pt-Ni nanorods were prepared by sequential electrodeposition of Pt and Ni into nanoporous anodic aluminum oxide membranes and characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The overall rod length and the total Pt segment length for different nanorods were kept at 1.6 (mu)m and 530 nm respectively by controlling conditions used in the galvanostatic electrodeposition.

Realizing combination drugs at a molecular level via drug-drug cocrystallization opens a new pathway for effective therapeutic hybrids. A "drug-bridge-drug" strategy is developed to cocrystallize two first-line antitubercular drugs isoniazid and pyrazinamide using fumaric acid as the bridge, overcoming the issue of hardly cocrystallizing two different drugs. The first example of ternary cocrystal with combination drugs exhibits optimized formulation capacity and in vitro/vivo synergistic effects, which provides a new insight into antituberculosis combination drugs. [ABSTRACT FROM AUTHOR]

We have investigated the gas-phase production of isoquinoline by performing collisional activation on benzalaminoacetal, the first intermediate in the classic solution-phase Pomeranz--Fritsch synthesis of isoquinoline. We have elucidated the reaction pathways in the gas phase using tandem mass spectrometry. Unlike the corresponding condensed-phase reaction, where catalytic proton exchange between intermediate(s) and solvent (Brønsted--Lowry base) is known to drive the reaction, the gas-phase reaction follows the "mobile proton model" to form the products via a number of intermediates, some the same as in their condensed-phase counterparts. Energy-resolved mass spectrometry, deuterium labeling experiments, and theoretical calculations (B3LYP/6-31G**) identified 27 different reaction routes in the gas phase, forming a complex interlinked reaction network. The experimental measurements and theoretical calculations confirm the proton hopping onto different basic sites of the precursors and intermediates to transform them ultimately into isoquinoline. [ABSTRACT FROM AUTHOR]

Conspectus: Bioorthogonal chemistry has had a major impact on the study of biological processes in vivo. Biomolecules of interest can be tracked by using probes and reporters that do not react with cellular components and do not interfere with metabolic processes in living cells. Much time and effort has been devoted to the screening of potential bioorthogonal reagents experimentally. This Account describes how our groups have performed computational screening of reactivity and mutual orthogonality. Our collaborations with experimentalists have led to the development of new and useful reactions. Dozens of bioorthogonal cycloadditions have been reported in the literature in the past few years, but as interest in tracking multiple targets arises, our computational screening has gained importance for the discovery of new mutually orthogonal bioorthogonal cycloaddition pairs. The reactivities of strained alkenes and alkynes with common 1,3-dipoles such as azides, along with mesoionic sydnones and other novel 1,3-dipoles, have been explored. Studies of "inverse-electron-demand" dienes such as triazines and tetrazines that have been used in bioorthogonal Diels-Alder cycloadditions are described. The color graphics we have developed give a snapshot of whether reactions are fast enough for cellular applications (green), adequately reactive for labeling (yellow), or only useful for synthesis or do not occur at all (red). The colors of each box give an instant view of rates, while bar graphs provide an analysis of the factors that control reactivity. This analysis uses the distortion/interaction or activation strain model of cycloaddition reactivity developed independently by our group and that of F. Matthias Bickelhaupt in The Netherlands. The model analyzes activation barriers in terms of the energy required to distort the reactants to the transition state geometry. This energy, called the distortion energy or activation strain, constitutes the major component of the activation energy. The strong bonding interaction between the termini of the two reactants, which we call the interaction energy, overcomes the distortion energy and leads to the new bonds in the products. This Account describes how we have analyzed and predicted bioorthogonal cycloaddition reactivity using the distortion/interaction model and how our experimental collaborators have employed these insights to create new bioorthogonal cycloadditions. The graphics we use document and predict which combinations of cycloadditions will be useful in bioorthogonal chemistry and which pairs of reactions are mutually orthogonal. For example, the fast reaction of 5-phenyl-1,2,4-triazine and a thiacycloheptyne will not interfere with the other fast reaction of 3,6-diphenyl-1,2,4,5-tetrazine and a cyclopropene. No cross reactions will occur, as these are very slow reactions. [ABSTRACT FROM AUTHOR]

Computational chemistry and biochemistry began with Isaac Newton's classical mechanics in the 17th century and the establishment of quantum mechanics in the 1920s. Enabled by extraordinary advances in computers, in the last half century, this field has become a robust partner with experiment. The challenges facing computational chemists and biochemists, the Holy Grails of the field, are described. These include the development of a highly accurate density functional, ideally one that has universal chemical accuracy, and accurate polarizable force fields, as well as methods to handle efficiently the massive number of computations that must be performed for molecular dynamics and for the computation of flexible systems such as proteins. We estimate when the breakthroughs that will make computation a powerful engine for chemical discovery and design will be achieved. The Holy Grails of this field involve methods to enable the accurate and efficient prediction of structures and properties of complex biological systems and materials. The principal Holy Grail is a routine computational method for the prediction and design of multicomponent, often heterogeneous, functional systems and devices. [ABSTRACT FROM AUTHOR]