Photoelectrochemistry on Ru(II)-2,2'-bipyridine-phosphonate-derivatized TiO2 with the I3-/I- and quinone/hydroquinone relays. Design of photoelectrochemical synthesis cells

Photocurrent measurements have been made on nanocrystalline TiO2 surfaces derivatized by adsorption of a catalyst precursor, [Ru(tpy)(bpy(PO3H2)2)(OH2)]2+, or chromophore, [Ru(bpy)2 (bpy(PO3H2)2)]2+ (tpy is 2,2':6',2' '-terpyridine, bpy is 2,2'-bipyridine, and bpy(PO3H2)2 is 2,2'-bipyridyl-4,4'-diphosphonic acid), and on surfaces containing both complexes. This is an extension of earlier work on an adsorbed assembly containing both catalyst and chromophore. The experiments were carried out with the I3-/I- or quinone/hydroquinone (Q/H2Q) relays in propylene carbonate, propylene carbonate-water mixtures, and acetonitrile-water mixtures. Electrochemical measurements show that oxidation of surface-bound Ru(III)-OH2(3+) to Ru(IV)=O(2+) is catalyzed by the bpy complex. Addition of aqueous 0.1 M HClO4 greatly decreases photocurrent efficiencies for adsorbed [Ru(tpy)(bpy(PO3H2)2)(OH2)]2+ with the I3-/I- relay, but efficiencies are enhanced for the Q/H2Q relay in both propylene carbonate-HClO4 and acetonitrile-HClO4 mixtures. The dependence of the incident photon-to-current efficiency (IPCE) on added H2Q in 95% propylene carbonate and 5% 0.1 M HClO4 is complex and can be interpreted as changing from rate-limiting diffusion to the film at low H2Q to rate-limiting diffusion within the film at high H2Q. There is no evidence for photoelectrochemical cooperativity on mixed surfaces containing both complexes with the IPCE response reflecting the relative surface compositions of the two complexes. These results provide insight into the possible design of photoelectrochemical synthesis cells for the oxidation of organic substrates.     

Design and Theoretical Study of Nickel Catalysts for Syndiotactic Polyolefins

A nickel catalyst was nodeled with ligand L^2,[NH=CH-CH=CH-0]^-,which should have potential use as a syndiotactic plyolefin catalyst,and the reaction mechanism was studied by theoretical calculations using the density functinal method at the B3LYP/LANL2MB level.The mechanism involves the formation of the intermediate [NiL^2Me]^ ,in which the metal occupies a T-shaped geometry.This intermediate has two possible structures with the methyl group trans either to the oxygen or to the nitrogen atom of L^2.The results show that both structures can lead to the desired product via similar reaction paths,A and B.Thus,the polymerization could be considered as taking place either with the alkyl group occupying the position trans to the Ni-0 or trans to the Ni-N bond in the catalyst.The polymerization process thus favors the catalysis of syndiotactic polyolefins.The syndiotactic synthesis effects could also be enhanced by varations in the ligand substituents.From energy considerations,we can conclude that it is more favorable for the methyl ttrans-O position to form a complex than to occupy the trans-N position.From bond length considerations,it is also more favoured for ethene to occupy the trans-O position than to occupy the trans-N position.     

一种新的环糊精衍生物手性固定相的合成及其在对映异构体过量值测定中的应用

 以 β 环糊精为原料 ,合成了一种新的环糊精衍生物 2 ,6 二 O 苄基 3 O 戊酰基 β 环糊精 ,用核磁氢谱和红外光谱对产物进行了表征 ,并将所得环糊精衍生物用作毛细管气相手性固定相制备成柱 ,用于 2 ,4 二氯苯乙酮的不对称催化氢化产物 2 ,4 二氯苯乙醇和反式 2 己烯醇的Sharpless环氧化产物 反式 3 正丙基环氧乙烷甲醇的对映异构体过量值 (e.e .值 )测定和催化反应评价 ,取得了很好的结果。     

新型高吸水聚合物凝胶型屏蔽暂堵剂MTC-1的合成及性能

以丙烯酸（AA）、丙烯酰胺（AM）、2-丙烯酰胺基-2-甲基丙磺酸（AMPS）为原料，蒙脱土（MMT）为改性剂，过硫酸钾和无水亚硫酸氢钠为氧化还原引发体系，六亚甲基四胺（C₆H₁₂N₄）为交联剂，采用水溶液聚合法合成了一种新型高吸水聚合物凝胶型屏蔽暂堵剂（MTC 1），其结构经IR表征。在最优合成条件（AM/AMPS/AA=11/7/1, m/m/m，引发剂加量0.6 wt%，于45 ℃反应2.5 h）下，MTC-1的最大吸水倍率为1006倍。岩心流动实验结果表明：MTC-1的堵水性能较高，封堵效率达到83.72%。     

液相色谱手性拆分机理的热力学方法研究

手性识别是分子识别的一个重要组成部分。液相色谱手性拆分机理研究有助于色谱条件的优化和新型手性固定相的设计，也有助于理解手性识别机制。本文就线性色谱与非线性色谱条件下手性拆分过程对应热力学参数的推求方法进行了评述，阐述了相关热力学参数的涵义及其在色谱保留及手性拆分机理探讨中的应用，并展望了该领域的研究前景。     

四氟乙烯-全氟4-甲基-3,6-二氧杂△~7辛基磺酰氟共聚物的分子运动

本工作用振簧仪,在-150—80℃范围内,测试了四氟乙烯-全氟4-甲基-3,6-二氧杂△~7辛基磺酰氟共聚物的动态力学性能。样品是含有不同侧基数目的部分结晶共聚物。观察到四个松弛过程,按温度下降次序记为α、γ_1-、γ_2-、γ_3-。α峰(室温附近)系玻璃化转变。γ_1峰(-50℃,～215Hz)为主链有阻碍的短链段分子运动。γ_2-峰(-60℃,～230Hz)为侧基的分子运动。γ_3-峰(-77℃,～260Hz)为的链段运动,并且γ_3-峰的强度随结晶度增加而增强。     

Recycling Chiral Organocatalyst （4S）-Phenoxy-（S）-proline for Direct Asymmetric Aldol Reaction in Ionic Liquid （bmim）PF6

Room temperature ionic liquid (bmim)PF6 was evaluated for recycling an organocatalyst (4S)-phenoxy-(S)-proline for direct asymmetric aldol reactions. The desired aldol products were obtained with good yields up to 93.2% and enantioselectivities up to 88.5%, and isolation of the products by simple extraction allowed recycling the ionic liquid containing the immobilized catalyst in subsequent reactions without significant decrease of yields and enantioselectivities.     

Elucidating Factors Manipulated the Formation of Multiply Charged Protein Homomultimeric Complexes by Electrospray Ionization

Native non‐covalently bonded protein‐protein and protein‐substrate complexes are of great interest and have been extensively studied by electrospray ionization mass spectrometry (ESI‐MS). Multiply charged protein homomultimeric complexes are shown to form by ESI‐MS. This study addresses factors that can artificially induce the formation of multiply charged protein homomultimeric complexes. Cytochrome c (Cyt c) and ubiquitin, which are monomers in solution, were found to generate (Cyt c)_mⁿ⁺ by electrospray ionization (ESI). The homomultimeric complexes were not limited to dimeric complexes but include also multiply charged trimers, tetramers, and pentamers. The observation of these homomultimeric complexes has never been revealed from a Cyt c solution at the concentration as low as 10 μM. Increasing the concentration of Cyt c enhanced the formation of (Cyt c)_mⁿ⁺ as expected; however, the protein concentration does not affect the relative intensities of monomeric and dimeric complexes. Additionally the enrichment of NH₄OH also promotes the formation of (Cyt c)_mⁿ⁺. Notably, source collision‐induced dissociations (source‐CID) of (Cyt c)_mⁿ⁺ alter the charge state distribution (CSD) and may lead to an incorrect interpretation of Cyt c conformations. Hence, extra care should be taken when using CSD to interpret the conformation of a protein derived from ESI‐MS.     

2-Deoxy-d-glucose Promotes Buforin IIb-Induced Cytotoxicity in Prostate Cancer DU145 Cells and Xenograft Tumors

Inhibition of the glycolytic pathway is a critical strategy in anticancer therapy because of the role of aerobic glycolysis in cancer cells. The glycolytic inhibitor 2-Deoxy-d-glucose (2-DG) has shown potential in combination with other anticancer agents. Buforin IIb is an effective antimicrobial peptide (AMP) with broad-spectrum anticancer activity and selectivity. The efficacy of combination treatment with 2-DG and buforin IIb in prostate cancer remains unknown. Here, we tested the efficacy of buforin IIb as a mitochondria-targeting AMP in the androgen-independent human prostate cancer cell line DU145. Combining 2-DG with buforin IIb had a synergistic toxic effect on DU145 cells and mouse xenograft tumors. Combination treatment with 2-DG and buforin IIb caused stronger proliferation inhibition, greater G1 cell cycle arrest, and higher apoptosis than either treatment alone. Combination treatment dramatically decreased L-lactate production and intracellular ATP levels, indicating severe inhibition of glycolysis and ATP production. Flow cytometry and confocal laser scanning microscopy results indicate that 2-DG may increase buforin IIb uptake by DU145 cells, thereby increasing the mitochondria-targeting capacity of buforin IIb. This may partly explain the effect of combination treatment on enhancing buforin IIb-induced apoptosis. Consistently, 2-DG increased mitochondrial dysfunction and upregulated Bax/Bcl-2, promoting cytochrome c release to initiate procaspase 3 cleavage induced by buforin IIb. These results suggest that 2-DG sensitizes prostate cancer DU145 cells to buforin IIb. Moreover, combination treatment caused minimal hemolysis and cytotoxicity to normal WPMY-1 cells. Collectively, the current study demonstrates that dual targeting of glycolysis and mitochondria by 2-DG and buforin IIb may be an effective anticancer strategy for the treatment of some advanced prostate cancer.     

Synthesis,photophysical and electrochemical studies of di-2-pyridyl ketone complexes of rhodium(III)

Complexes of rhodium(III) with di-2-pyridyl ketone (dpk), Rh(dpk)(MeCN)Cl₃ (1) and cis-[Rh(dpk)₂Cl₂]⁺ (2), have been successfully prepared and characterized. At low temperature (77 K), complex (2) in EtOH/MeOH (4:1, v/v) shows a broad, symmetric and structureless red emission with a microsecond lifetime and, hence, is assigned as the dd* phosphorescence. Electrochemical data, including cyclic voltammetry, normal pulse voltammetry, triple pulse voltammetry and controlled potential electrolysis, have been obtained for the two dpk complexes of rhodium(III) in MeCN. On the basis of analysis of the electrochemical (1,2) and luminescence data (2), electron transfer mechanisms are proposed. For complex (1), two reduction processes occur at the metal-localized orbitals with elimination of chlorides during the first reduction step. This is followed by a one-electron reduction at the metal. For complex (2), three electrons are transferred to the metal in two successive reduction steps accompanied by elimination of two chlorides. After these two reduction steps another one-electron reduction occurs at the dpk ligand.