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The study reported that the charge transfer (CT) spectra of the pi-pi complexes formed by several aromatic amines and nitrogen heterocycle [acting as donors (Ds)] with acceptor A [A = tetracyanoethylene (TCNE), chloranil (CA)] was measured in acetonitrile. The density functional theory calculations were carried out in solvent to determine the probable geometric structure of the complexes that were responsible for the absorption bands.

Research has been conducted on the carbohydrate-binding peptides. The reactivity of these peptides has been investigated and the results are presented.

Results suggest that the heterolytic N-H bond dissociation is largely favored to that of homolytic bond dissociation and the electron removal/addition from the parent molecule activates the N-H bond cleavage under alkaline pH conditions. Furthermore, the (N-H) homolysis is preferred over the heterolysis.

The rate constants of the hydride-transfer reactions from isopropyl alcohol (i-PrOH) to an [NAD.sup.+] model, 9-phenylxanthylium (Ph[Xn.sup.+]), in acetonitrile (AN) and in water containing AN are determined over a wide temperature range. The results have shown that in the alcohol dehydrogenases without a Zn(II) cofactor in the active sites alcohols is oxidized by hydride transfer to [NAD.sup.+] coenzyme followed by the rapid deprotonation to the nearby basic species in the active site of the enzymes.

The article explains the dissociation of the different subunits of the calcium-independent receptor of [alpha]-latrotoxin (CIRL), a neuronal cell surface receptor. A two-step proteolytic processing that controls the cell surface expression of different types of CIRL is also discussed.

The alcohol medium containing acetonitrile or water was employed to study the kinetics, the deuterium isotope effects and the mechanism of the hydride-transfer reaction from isopropyl alcohol to two stable organic cations ([NAD.sup.+] analogues). The results obtained provide insight into the biological hydride-transfer reaction mechanism and the function of the Zn(II) ion in the active site of the alcohol dehydrogenases reactions.

An attempt is made to highlight that in a series of reactions, if a reactive impurity affects the kinetics in one reaction, then it would exert a consistent effect on the kinetics of all of the reactions in the series. Experimental data for three different series of reaction, proton transfer reactions of 2,6-dimethylpyridine, 2,6-diethylpyridine, and 2,6-diphenylpyridine with four different methylanthracene radical cations, were concurrently examined for possible reactant impurity problems.

Norcarane was employed as a mechanistic probe in oxidations catalyzed by hepatic cytochome P450 enzymes and by the soluble methane monooxygenase enzyme from methylococcus capsulatus. Generalizations regarding the intermediacy of radicals in P450 and soluble methane monooxygenase (sMMO) enzyme-catalyzed hydroxylations based on the norcarane results should be considered hypothetical until the origin of the unanticipated results can be determined.

The Diels-Alder effect among the anthracene and tetracyanoethylene in acetonitrile does not move to a consistent mode in its initial half-life. The kinetics of the effects, are revealed in the microscopic rate constants for the distinct levels.

Three novel organic amine templated honeycomb-like lanthanide sulfates, (C4N2H12)3[Ln3(OH)(SO4)7] (Ln = Sm (1), Eu (2), and Tb (3)), with extra-large channels containing 24-membered rings (24MR) have been synthesized by using chair form piperazine as the structure-directing agent under one-pot solvothermal reactions. The three compounds are isostructural, and the open framework of the tide compounds is the first lanthanide sulfate example with extra-large channels containing 24MR. It has an acs framework topology. The three compounds are strong luminescent materials that display characteristic Sm3+, Eu3+, and Tb3+ emission bands in the visible region. The observed second-harmonic generation efficiencies of the three compounds are all 0.4 times that of urea. TGA profiles and XRD measurements demonstrate their high thermal stability. [ABSTRACT FROM AUTHOR]

A Mn(II)-based homometallic porous metal-organic framework, Mn5(btac)4(µ3-OH)2(EtOH)2·DMF·3EtOH·3H2O (1, btac = benzotriazole-5-carboxylate), has been solvothermally synthesized and structurally characterized by elemental analysis, thermogravimetric analysis, and X-ray crystallographic study. 1 is a 3D neutral framework featuring 1D porous channels constructed by {Mn-OH-Mn}n chains and btac linkers. Magnetic studies show that 1 is a 3D metamagnet containing 1D {Mn-OH-Mn}n ferrimagnetic chains. High-pressure H2 adsorption measurement at 77 K reveals that activated 1 can absorb 0.99 wt % H2 at 0.5 atm and reaches a maximum of 1.03 wt % at 5.5 atm. The steep H2 absorption at lower pressure (98.2% of the storage capacity at 0.5 atm) is higher than the corresponding values of some MOFs (MIL-100 (16.1%), MOF-177 (57.1%), and MOF-5 (22.2%)). Furthermore, activated 1 can adsorb CO2 at room temperature and 275 K. The adsorption enthalpy is 22.0 kJ mol-1, which reveals the high binding ability for CO2. Detailed gas sorption implies that the exposed Mn(II) coordination sites in the activated 1 play an important role to improve its adsorption capacities. [ABSTRACT FROM AUTHOR]

The rate constants of the hydride-transfer reactions from isopropyl alcohol (i-PrOH) to an NAD model, 9-phenylxanthylium ion (PhXn+), in acetonitrile (AN) and in water containing AN (80% H2O/ 20% AN) were determined over a temperature range from 36 to 67 °C. The reactions follow second- order rate laws. In the latter solution, formation of the water adduct of PhXn+ was observed as a side- equilibrium (K). The observed inverse solvent kinetic isotope effect (kH2Oobs/kD2Oobs= 0.54), the larger than unity equilibrium isotope effect (K(H2O)/K(D2O) = 2.69), and the results of acid effect on the observed rate constants of the reactions are consistent with the "side-equilibrium mechanism". Kinetic isotope effects at all three H/D positions of i-PrOH for the net hydride-transfer process were determined in both solutions at 60 °C KIEα-DH = 3.2(AN), 3.2(1-120); KIEβ-D6H = 1.05(AN), 1.16(H2O); KIEβD6 = 1 .08(AN), 1.04(H2O). These KIE values are consistent with the presence of the positively charged alcohol moiety in the transition state (TS) for cleavage of the α-C-H bond, the delocalization of the positive charge over the α-C-OH group, and the stepwise hydride and proton transfer processes. Comparison of theactivation parameters for the reactions in the two solvent systems as well as those in the i-PrOH/AN (1:1 v/v) reported earlier suggests that the AN medium promotes the reaction by activating the ground-state alcohol reactant through weak interactions with the electron pairs on alcohol O, while water and parent alcohol media facilitate the reaction by H-bonding stabilization of the alcohol moiety of the TS. Results suggest that in the alcohol dehydrogenases without a Zn(lI) cofactor in the active sites alcohols would be oxidized via hydride transfer to NAD+ coenzyme followed by the rapid deprotonation to the nearby basic species in the active site of the enzymes. [ABSTRACT FROM AUTHOR]

Observed pseudo-first-order rate constants (kobs) of the hydride-transfer reactions from isopropyl alcohol (i-PrOH) to two NAD+ analogues, 9-phenyixanthylium ion (PhXn+) and 10-methylacridinium ion (MA+), were determined at temperatures ranging from 49 to 82 °C in i-PrOH containing various amounts of AN or water. Formations of the alcohol-cation ether adducts (ROPr-i) were observed as side equilibria. The equilibrium constants for the conversion of PhXn+ to PhXnOPr-i in i-PrOH/AN (v/v = 1) were determined, and the equilibrium isotope effect (EIE K(i-PrOH)/K(i-PrOD)) at 62 °C was calculated to be 2.67. The kH of the hydride-transfer step for both reactions were calculated on the basis of the kobs and K. The corresponding deuterium kinetic isotope effects (e.g., KIEODH = kH(i+PrOH)/kH(i-PrOD) and KIEβ-D6H = kobs(i-PrOH)/kobs((CD3)2CHOH)), as well as the activation parameters, were derived. For the reaction of PhXn+ (62 °C) and MA+ (67 °C), primary KIEα-DH (4.4 and 2.1, respectively) as well as secondary KIEODH (1.07 and 1.18) and KIEβ-D6H (1.1 and 1.5) were observed. The observed EIE and KIEODH were explained in terms of the fractionation factors for deuterium between OH and OH+(OHδ+) sites. The observed inverse kinetic solvent isotope effect for the reaction of PhXn+ (kobs(i-PrOH)/kobs(i-PrOD) = 0.39) is consistent with the intermolecular hydride-transfer mechanism. The dramatic reduction of the reaction rate for MA+, when the water or i-PrOH cosolvent was replaced by AN, suggests that the hydride-transfer T.S. is stabilized by H-bonding between 0 of the solvent OH and the substrate alcohol OHδ+. This result suggests an H-bonding stabilization effect on the T.S. of the alcohol dehydrogenase reactions. [ABSTRACT FROM AUTHOR]

Studies the kinetics of the proton transfer reactions between the 9-methyl-10-phenylanthracene radical cation with 2,6-lutidine using derivative cyclic voltammetry. Deuterium kinetic isotope effects; Characteristics of the methylarene cations; Mechanism for the proton transfer reactions of radical cations; Proton tunneling in organic reactions.

Examines the proton-transfer reactions between nitroalkanes and hydroxide ion under non-steady-state conditions. Visibility of real kinetic and isotopic effects; Exhibition of strong absorbance bands in the visible spectral region; Equilibrium constants of the reactions; Temperature dependence of the rate constants for proton and deuteron transfers.

Protein-based electronic biomaterials represent an attractive alternative to traditional metallic and semiconductor materials due to their environmentally benign production and purification. However, major challenges hindering further development of these materials include (1) limitations associated with processing proteins in organic solvents and (2) difficulties in forming higher-order structures or scaffolds with multilength scale control. This paper addresses both challenges, resulting in the formation of one-dimensional bundles composed of electrically conductive protein nanowires harvested from the microbes Geobacter sulfurreducens and Escherichia coli . Processing these bionanowires from common organic solvents, such as hexane, cyclohexane, and DMF, enabled the production of multilength scale structures composed of distinctly visible pili. Transmission electron microscopy revealed striking images of bundled protein nanowires up to 10 μm in length and with widths ranging from 50-500 nm (representing assembly of tens to hundreds of nanowires). Conductive atomic force microscopy confirmed the presence of an appreciable nanowire conductivity in their bundled state. These results greatly expand the possibilities for fabricating a diverse array of protein nanowire-based electronic device architectures.

We present novel nanoporous TiO(2)/polyion thin-film-coated long-period fiber grating (LPFG) sensors for the direct measurement of low-molecular-weight chemicals by monitoring the resonance wavelength shift. The hybrid overlay films are prepared by a simple layer-by-layer deposition approach, which is mainly based on the electrostatic interaction of TiO(2) nanoparticles and polyions. By the alternate immersion of LPFG into dispersions of TiO(2) nanoparticles and polyions, respectively, the so-formed TiO(2)/polyion thin film exhibits a unique nanoporous internal structure and has a relative higher refractive index than LPFG cladding. In particular, the porosity of the thin film reduces the diffusion coefficient and enhances the permeability retention of low-molecular-weight analytes within the porous film. The increases in the refractive index of the LPFG overlay results in a distinguished modulation of the resonance wavelength. Therefore, the detection sensitivity of LPFG sensors has been greatly improved, according to theoretical simulation. After the structure of the TiO(2)/polyion thin film was optimized, glucose solutions as an example with a low concentration of 10(-7) M was easily detected and monitored at room temperature.