Mechanism of Catalytic Effect of Water Clusters on the Oxidation of Phosphine Gas

Russian Journal of Physical Chemistry A - The mechanism of PH3 oxidation is investigated at B3LYP/6-311+g (d, p) level using density functional theory calculation with n = 0–6 water molecules...     

柚皮素/β-环糊精超分子体系的包合行为

本文采用超声法制备了柚皮素（NAR）与β-环糊精（βCD）的包合物.粉末-X射线衍射（XRD）和红外吸收光谱（IR）测定均表明形成的包合物具有不同于主客体的新的结构性质.¹H NMR与ROESY核磁共振（NMR）实验表明NAR以苯环端从βCD的宽口端进入，并形成稳定的超分子包合物.量子化学计算分析NAR/βCD包合物的形成过程表明，驱动力源于焓驱动与氢键弱相互作用力；能隙和结合能分析得到的最优包合模式与NMR研究结果一致；ONIOM分层计算验证了上述结果.分子对接模拟出的最优包合模式也与量子化学计算、NMR的分析结果吻合.本文获取了清晰的NAR/βCD包合物构型及其形成机理，为该超分子药物的定量构效关系研究提供了理论参考.     

Modified MCM-41 as a drug delivery system for acetylsalicylic acid

The modification of prepared MCM-41 by different groups (amino, chloro and oxo) was studied. Prepared materials were treated by acetylsalicylic acid and hybrid materials were characterized, compared from the point of view of immobilized amount of active substance. The highest amount of acetylsalicylic acid was detected using methyl-tert- butyl ether as a solvent and MCM-41 without modification after 1 h (0.35 g per 1 g of the support) or MCM modified by amino group after 5 h (0.37 g per 1 g of the support) as a support. Using amino modified MCM, the longer treatment by acetylsalicylic acid converged to the equilibrium and after 24 h the immobilized amount was 0.3 g per 1 g. A dissolution in vitro study was carried out, comparing the stability of formed interactions. The slowest dissolution was detected using non-modified MCM-41 and oxo modified material.     

Identifying a dot-matrix hologram with the fringe-overlapping phenomena of grating dots

Dot-matrix holograms created by two-beam writers contain many grating dots. Because the phase difference between two laser beams for interference cannot be controlled accurately, the fringe positions of grating dots are randomly determined. Therefore, fringe positions are a good kind of tool to identify dot-matrix holograms. In this paper, a number difference between two special fringes of a target grating dot is used to identify a dot-matrix hologram. The two special fringes are determined by three grating dots with parallel fringes. The first special fringe is corresponding to a fringe pair with the best matching for the fringes of the target grating dot and the fringes of the second grating dot. The second special fringe is corresponding to a fringe pair with the best matching for the fringes of the target grating dot and the fringes of the third grating dot. An experiment has proved the proposed method practical and feasible. Because reproducing a grating dot with a specified fringe number difference is difficult, the proposed method is excellent for anti-counterfeiting.     

An improved Pfitzinger reaction: Eco-efficient synthesis of quinaldine-4-carboxylates by TMSCl-mediated

We report herein an improved Pfitzinger reaction for the synthesis of highly functionalized quinaldines from 1,3-dicarbonyl compounds, isatins and alcohols mediated by TMSCl. This synthesis involves cyclization and esterification in one-step cascade process for the formation of a carboxylate (CO₂R) at the 4-position of quinaldine ring. Moreover, this procedure shows highly efficient, good functional group tolerance, operational simplicity, environment-friendly and feasibility of scale up.     

十二烷基二甲基苄基氯化铵从碱性氰化液中固相萃取金的研究

建立了一种用十二烷基二甲基苄基氯化铵(BDMDAC)从碱性氰化液中固相萃取金的新方法：在碱性介质中,十二烷基二甲基苄基氯化铵溶液(BDMDAC)与Au(CN)2-络阴离子生成离子缔合物,该离子缔合物可被反相键合硅胶固相萃取柱萃取、富集,用乙醇洗脱,反相键合硅胶固相萃取柱可重复使用。该方法用于从碱性氰化液中固相萃取痕量金,萃取回收率可超过98%。     

多联吡啶Pt(Ⅱ)、Pd(Ⅱ)配合物的合成及制氢研究

把电子受体苄基紫精引入到多联吡啶中,设计合成了新型三齿多吡啶配体[HC∧N∧N(PhMV2+Ph)],并以其合成了新配合物[C1Pt{C∧N∧N(PhMV2+Ph)}](ClO4)、[C1Pd{C∧N∧N(PhMV2+Ph}](PF6)2。用核磁共振氢谱表征了配体和配合物的结构,证实所得合成产物与设计结构一致;利用UV研究了配体及配合物的光谱性质,两种配合物在可见光区有MLCT吸收;采用三组分的"S-R/D/C"体系,对配合物[C1Pt{C∧N∧N(PhMV2+Ph)}](ClO4)2的光解水制氢行为进行了初步研究,并与[ClPt{C^N^N(PhMV2+)}](PF6)2及没有实现敏化剂与电子中继体MV2+直接连接的四组分体系ClPt[C∧N∧N(PhCH3)]做了对比。结果表明对于光敏剂与电子受体共价连接的Pt(Ⅱ)多吡啶类配合物,制氢效果并没有提高。     

Synthesis,isolation and characterization of methyl levulinate from cellulose catalyzed by extremely low concentration acid

A direct synthesis of methyl levulinate from cellulose alcoholysis in methanol medium under mild condition (180–210 °C) catalyzed by extremely low concentration sulfuric acid (≤0.01 mol/L) and the product isolation were developed in this study. Effects of different process variables towards the catalytic performance were performed as a function of reaction time. The results indicated that sulfuric acid concentration, temperature and initial cellulose concentration had significant effects on the synthesis of methyl levulinate. An optimized yield of around 50% was achieved at 210 °C for 120 min with sulfuric acid concentration of 0.01 mol/L and initial cellulose concentration below 100 g/L. The resulting product mixture was isolated by a distillation technique that combines an atmospheric distillation with a vacuum distillation where n-dodecane was added to help distill the heavy fraction. The light fraction including mainly methanol could be reused as the reaction medium without any substantial change in the yield of methyl levulinate. The chemical composition and structural of lower heavy fraction were characterized by GC/MS, FTIR, ¹H-NMR and ¹³C-NMR techniques. Methyl levulinate was found to be a major ingredient of lower heavy fraction with the content over 96%. This pathway is efficient, environmentally benign and economical for the production of pure levulinate esters from cellulose.     

Microwave‐Assisted Synthesis of Ethyl 1,3‐Disubstituted‐1,6‐dihydropyrrolo[2,3‐c]pyrazole‐5‐carboxylates

A novel series of ethyl 1,3‐disubstituted‐1,6‐dihydropyrrolo[2,3‐c]pyrazole‐5‐carboxylates can be rapidly and efficiently synthesized in excellent yields by condensing a variety of 1,3‐substituted‐4‐formyl‐5‐chloropyrazole with ethyl isocyanoacetate in the presence of 1‐methyl‐3‐butylimidazolium hydroxide under microwave irradiation. The simple experimental procedure, DMSO‐free condition, short period of conversion, and excellent yields are the advantages of the present method. The structures of the novel compounds are confirmed by IR, ¹H NMR, ¹³C NMR, MALDI‐TOF MS, and elemental analysis.