The rhodium complex of a tris(bipyridine) ligand—Its electrochemical behaviour and function as mediator for the regeneration of NADH from NAD+

The tris-bipyridine ligand3a and its stoichiometric Rh³⁺ complex have been prepared. Cyclovoltammograms of the complex at pH 7.4 using a glassy carbon disk electrode reveal a strong reduction peak at –620 mV and two weak reduction peaks at more negative voltage. The reduction potential of the new complex is shifted by 300 mV to more positive values as compared to [Rh(bipy)₃]³⁺. There is no reversible reoxidation peak of the Rh(I) complex formed due to the decomplexation of one of the three bipyridine units in the course of the transition Rh(III)Rh(I). The Rh(III) complex of3a was also studied with respect to its function as a possible redox mediator for the electrochemical regeneration of NADH from NAD⁺. The preparative electrolysis of the Rh³⁺ complex of3a in the presence of NAD⁺ yields a selective formation of NADH, whereas NAD dimers were not detected. On the other hand, a significant acceleration of this reaction compared to [Rh(bipy)₃]³⁺ was not observed.     

Versatile synthesis of chiral 2-substituted-5-oxo-1,2,3,4-tetrahydro-5H-1,4-benzodiazepines as novel scaffolds for peptidomimetic building

The stereocontrolled synthesis of phenylalanine and tryptophan derived 5-oxo-1,2,3,4-tetrahydro-5H-1,4-benzodiazepine derivatives is described. This new methodology involves a modified Strecker reaction of N-Boc protected amino aldehydes and methyl anthranilate, reduction of the resulting α-amino nitriles, and lactamization. The resulting 2-substituted-5-oxo-1,2,3,4-tetrahydro-5H-1,4-benzodiazepines were further functionalized at position 4 by alkylation or acylation reactions. One of these new tryptophan-derived 1,4-benzodiazepines showed significant selective binding affinity at cholecystokinin CCK₁ receptors (IC₅₀=156.5±33.2 nM).     

Photocatalytic Reduction of NO with C2H6 on a Hollandite-Type Catalyst

The photocatalytic reduction of nitrogen monoxide (NO) with ethane on the hollandite type catalyst (K₂Ga₂Sn₆O₁₆KGSO) was investigated. Using a closed-gas circulating system equipped with a Q-MASS detector and in-situ diffuse reflectance FT-IR spectroscopy. The reactant gases of NO and ¹³C₂H₆ decreased with the increasing irradiation time. In contrast, the N₂ yield increased proportionally to the conversion of ¹³C₂H₆. Nitrogen oxides such as N₂O did not reach their detectable levels. The NO adsorbed on KGSO was found to change to its activated species by UV irradiation. The oxidized products of C₂H₆ such as CH₃CHO increased in proportion to the reaction time. The present results strongly suggest that KGSO has remarkable photocatalytic activity for the reduction of NO with C₂H₆.     

The Electrochemistry of Tetraphenyl Porphyrin Iron(III) Within Immobilized Droplets Supported on Platinum Electrodes

For the first time, the voltammetry of an ensemble of immobilized benzonitrile microdroplets containing 5,10,15,20‐tetraphenyl‐21H,23H‐porphine iron (III) chloride, TPPFeCl immobilized at platinum electrodes immersed in various aqueous electrolytes has been explored. The reduction of TPPFeCl was observed with the voltammetric response seen to be highly dependent on the nature of ions in the surrounding aqueous phase. Unlike voltammetry in purely homogeneous solution the nature of the aqueous electrolyte can influence the voltammetry in the droplet phase. The electrochemical reduction of TPPFeCl contained within tetrabutylammonium chloride (TBACl) supported benzonitrile (PhCN) microdroplets immersed into an aqueous solution of TBACl was first studied. During TPPFeCl reduction the resulting [TPPFeCl]^? species is stabilized due to the excess of chloride anions inside the oil droplet. Voltammograms of homogeneous solutions of PhCN supported with TBACl show similar chemically reversible process which is also attributed to the stable [TPPFeCl]^? species. This anion stabilization was not observed when the oil droplets were supported with tetrabutylammonium perchlorate (TBAP) or when the PhCN solution bathing the microdroplet ensemble was supported with TBAP resulting in a chemically irreversible process. The voltammetry of unsupported droplets immobilized on a platinum electrode immersed in different aqueous electrolytes was also explored and the fate of the [TPPFeCl]^? species formed considered during the reduction sweep. Similarities and difference to voltammetry in purely homogeneous media are noted and the use of droplet voltammetry provides complimentary information.     

低于300℃时两种氧化铈材料对稀燃阶段NOx存储性能的影响

研究了低于300 ℃时两种氧化铈对稀燃阶段NO_x存储性能的影响,催化剂由2%（w）Pt/Al₂O₃（PA）与CeO₂-X（X=S,I）机械混合制备. X射线衍射（XRD）,BET表面积和扫描电子显微镜（SEM）用于表征材料的物理结构. X射线光电子能谱（XPS）和H₂程序升温还原（H₂-TPR）用于表面Ce³⁺和活性氧定量. 原位漫反射傅里叶变换红外光谱（in-situ DRIFTS）用于分析表面NO_x吸附物种. 相比于CeO₂-I,CeO₂-S 具有优良的物理化学性能,包括高比表面积、丰富的空隙结构、较高的抗老化能力及表面Ce³⁺浓度. 因而,Pt/Al₂O₃+CeO₂-S 表现出优异的NO_x存储能力. 此外,PA+CeO₂-X（X=S,I）上存在Pt 与CeO₂之间的相互作用,可提高表面氧物种的活性进而促进NO氧化及NO_x存储. PA+CeO₂-S上的这种相互作用要强于PA+CeO₂-I. 研究表明,表面Ce³⁺浓度和活性氧含量对NO_x存储起到重要作用. 然而经过水热处理后,Pt 与老化的氧化铈（ACS,ACI）之间的相互作用降低,并且两种氧化铈NO_x存储性能显著下降. 另外,与PA+ACS（ACI）相比,PA+PACS（PACI）样品NO_x存储能力得到改善,这归因于表面氧物种活性增加能促进硝酸盐的形成.     

Direct Electrochemistry of Multi‐Copper Oxidases at Carbon Nanotubes Noncovalently Functionalized with Cellulose Derivatives

This study describes the direct electron transfer of multi‐copper oxidases, i.e., laccase (from Trametes versicolor) and bilirubin oxidase (BOD, from Myrothecium verrucaria) at multiwalled carbon nanotubes (MWNTs) noncovalently functionalized with biopolymers of cellulose derivatives, i.e., hydroxyethyl cellulose (HEC), methyl cellulose (MC), and carboxymethyl cellulose (CMC). The functionalization of the MWNTs with the cellulose derivatives is found to substantially solubilize the MWNTs into aqueous media and to avoid their aggregation on electrode surface. Under anaerobic conditions, the redox properties of laccase and BOD are difficult to be defined with cyclic voltammetry at either laccase/MWNT‐modified or BOD/MWNT‐modified electrodes. The direct electron transfer properties of laccase and BOD are thus studied in terms of the bioelectrocatalytic activities of the laccase/MWNT‐modified and BOD/MWNT‐modified electrodes toward the reduction of oxygen and found to be facilitated at the functionalized MWNTs. The possible application of the laccase‐catalyzed O₂ reduction at the laccase/MWNT‐modified electrode is illustrated by constructing a CNT‐based ascorbate/O₂ biofuel cell with the MWNT‐modified electrode as the anode for the oxidation of ascorbate biofuel.     

Synthesis of nanosized TiO2/SiO2 particles using microwave processes and their photocatalytic activity on the decomposition of orange II

The nanosized titania and TiO₂/SiO₂ particles were prepared by the microwave-hydrothermal method. The effect of physical properties TTIP/TEOS ratio and calcination temperature has been investigated. The major phase of the pure TiO₂ particle is of the anatase structure, and a rutile peak was observed above 800°C. In TiO₂/SiO₂ particles, however, no significant rutile phase was observed, although the calcination temperature was 900°C. No peaks for the silica crystal phase were observed at either silica/titania ratio. The crystallite size of TiO₂/SiO₂ particles decreases as compared to pure TiO₂ at high calcination temperatures. The TiO₂/SiO₂ particles show higher activity on the photocatalytic decomposition of orange II as compared to pure TiO₂ particles.     

Simultaneous Reduction of Nitro Group and S-S Bond in Nitrodisulfides by Samarium Diiodide: A New Approach to Benzothiazolines

Asapowerfulandversatileone-electrontransferreductant,Sml,hasbeenappliedwidelyinorganicsynthesis'.OurpreviousworksonthereductionofnitrocompoundsandreductivecleavageofS-S,Se-Se,Te-TebondswithSml,'ledustoinvestigatethesimultaneousreductionofnitrogroupandS-SbondbySml,.Benzothiazolinesderivativesareimportantreagentsandusefulintermediatesinorganicsynthesisandpharmaceuticalchemistry.Forinstance,theycanbeusedasadditionagentsforphotographicemulsions",effectiveacaricides",antituberculousagents",lubr…     

Developments on carbon dioxide reduction: Their promise,achievements, and challenges

CO₂ reduction processes continue to be developed for electrosynthesis, energy storage applications, and environmental remediation. A number of promising materials have shown high activity and selectivity to target reduction products. However, the progress has been mainly at a small laboratory scale, and the technical challenges of large scale CO₂ reduction have not been considered adequately. This review covers recent advancements in catalyst materials and cell designs. The leading materials for CO₂ reduction to a number of useful products are presented with their corresponding cell and reactor designs. The latest efforts to progress to industrially relevant scales are discussed, along with the challenges that must be met for carbon dioxide reduction to be a viable route for mass scale production.     

Effect of NO, SO2, and O2 on the conversion of nitrous oxide on iron-containing zeolite catalysts

Conditions were found for facilitation of the conversion of nitrous oxide in the presence of Fe-containing zeolite catalysts by oxidants (NO, SO₂, and O₂). The results were interpreted in the framework of a mechanism involving decomposition of N₂O. The effect of NO_x on the reduction of nitrous oxide by C₃-C₄ alkanes was established. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 4, pp. 241–245, July–August, 2006.