不对称方酸染料的电子结构与光导性的从头算研究

用量子化学从头算法,在RHF/6-31G(d,p)水平上优化了八种不对称方酸染料的分子构型,并对它们的分子内电荷转移程度与暗衰值,光敏值和最大吸收波长的定量关系进行研究,发现不对称方酸染料的分子内电荷转移性质,是影响不对称方酸染料光导性和最大吸收波长的重要因素。     

常低温相变储热材料的研究和应用

将常低温相变储热材料分类,介绍了常低温相变储热材料的种类及各自特点,对固-液相变、固-固相变储热材料的性能、优缺点和应用进行了讨论,讲述了目前人们针对常低温相变储热材料的缺陷采取的解决方法。     

The development for the synthesis of chiral acyclic nucleosides and their phosphonates

Acyclic nucleosides and their phosphonates possess significantly antiviral and cytostatic activities. For acyclic nucleosides and their phosphonates, the introduction of a chiral group to their side chain or the absolute configuration of the chiral atom could affect their biological activities obviously. Thus, the asymmetric synthesis of chiral acyclic nucleosides and their phosphonates has received continuous attention. The previous reports mainly focus on employing the chiral pool and chiral auxiliary methods for the synthesis of chiral acyclic nucleosides and their phosphonates. In contrast, the asymmetric catalysis methods for the synthesis of acyclic nucleosides and their phosphonates are still in the beginning. This digest paper will serve to highlight the significant progress that has been made in these areas.     

Polymer Networks: A Challenge to Theorist and Technologist

Polymer networks challenge a theorist to develop methods of their generation, describe their topology, and understand critical phenomena (gelation) during their formation. They challenge a technologist because of their unique properties based on their large-scale three-dimensional connectivity and their easy transformation of relatively low-viscosity liquids into crosslinked solids. Polymer networks challenge both, in that they are structurally very complex for the technologist who needs the theorist for understanding and controlling their structure and properties. Also, the theorist is challenged by problems appearing in technology which may initiate a basic reconsideration of the theories' assumptions. In this contribution, methods for modeling polymer network structures and their recent applications to relatively complex systems of technological importance are briefly discussed.     

New strategies to study the chemical nature of wine oligomeric procyanidins

Tannins represent a key element in red wine flavors, so researchers have made a lot of effort to try to understand the role of their structure in wine taste in recent decades. We report some new routes to achieve a true structure–taste relationship for the major tannins found in wine, which are procyanidins in their monomeric or oligomeric state. All these routes use synthetic standards. New advances in their synthesis and their analyses using chromatographic methods, NMR spectroscopy, and mass spectrometry to obtain more precise information about their chemical structure, including their stereochemistry and their precise degree of polymerization and galloylation, are described.     

V2O5/高硅分子筛的酸性与甲苯气相选择氧化

用固体离子交换法制备了Ｖ２Ｏ５／ＺＳＭ－５和Ｖ２Ｏ５／丝光沸石两类催化剂。通过ＸＲＤ，ＬＲＳ，ＸＰＳ和Ｓｇ测定表征了Ｖ２Ｏ５在分子筛上的分散状态。用吡啶吸附红外光谱法和正丁胺非水溶液回滴法研究了催化剂的表面酸性。用ＥＳＲ研究了甲苯在催化剂上的吸附。结果表明，催化剂的酸性不同，它们吸附甲苯的能力也不同，对甲苯气相选择氧化的活性和选择性也有较大的差异。同时，甲苯选择氧化成苯甲醛的能力还与Ｖ２Ｏ５在分子     

食物的色、香、味与食品添加剂

食品添加剂可以改善食品的品质,延长食品的保存期,增加食品的营养成分。本文介绍了生活中常见的食品添加剂：食品色素、食用香料、甜味剂、鲜味剂、防腐剂和抗氧化剂的性能、使用范围和化学结构。以便于在化学教学中开阔学生的知识视野,提高学生的学习兴趣,全面培养学生的科学素质。     

Biosynthesis of DNA-Alkylating Antitumor Natural Products

DNA-alkylating natural products play an important role in drug development due to their significant antitumor activities. They usually show high affinity with DNA through different mechanisms with the aid of their unique scaffold and highly active functional groups. Therefore, the biosynthesis of these natural products has been extensively studied, especially the construction of their pharmacophores. Meanwhile, their producing strains have evolved corresponding self-resistance strategies to protect themselves. To further promote the functional characterization of their biosynthetic pathways and lay the foundation for the discovery and rational design of DNA alkylating agents, we summarize herein the progress of research into DNA-alkylating antitumor natural products, including their biosynthesis, modes of action, and auto-resistance mechanisms.     

聚乳酸类医用生物降解材料的研究进展

聚乳酸由于其突出的优点如生物相容性好、降解产物对人体无毒而倍受重视,并且在生物医学领域的应用中获得了很好的效果。本文对聚乳酸的合成及在医学方面的应用作了总结和评述,并对其在生物医学领域的应用前景作了进一步展望。     

N-heterocyclic carbenes as organocatalysts

Organocatalyzed reactions represent an attractive alternative to metal-catalyzed processes notably because of their lower cost and benign environmental impact in comparison to organometallic catalysis. In this context, N-heterocyclic carbenes (NHCs) have been studied for their ability to promote primarily the benzoin condensation. Lately, dramatic progress in understanding their intrinsic properties and in their synthesis have made them available to organic chemists. This has resulted in a tremendous increase of their scope and in a true explosion of the number of papers reporting NHC-catalyzed reactions. Here, we highlight the ever-increasing number of reactions that can be promoted by N-heterocyclic carbenes.     

Spectral characterization,antimicrobial and antibiofilm activity of poly(propylene imine) metallodendrimers in solution and applied onto cotton fabric

Abstract

Poly(propylene imine) dendrimers from first and third generation modified with 1,8-naphthalimide units and their Cu(II) complexes have been characterized by fluorescence and EPR spectroscopy. Cotton fabric has been modified with these dendrimers and their color characteristics were determined. The antimicrobial activity of dendrimer ligands and their Cu(II) complexes in solution and after their deposition on a cotton fabric was investigated. Good antibacterial effect of dendrimer ligands has been obtained, which is enhanced at their Cu(II) complexes. After their deposition on cotton fabric metallodendrimers exhibit good antibiofilm activity.     

Measurement of nanoparticles by light-scattering techniques

Nanoparticles (NPs), due to their unique physical and chemical properties, especially their minute particle size (?100 nm), find applications in numerous industrial, commercial and consumer products. After their end-user applications, these NPs find their way into the environment and food products. The NPs so discharged need to be quantified accurately to determine their toxicity and exposure levels.At this time, there is a need to develop a unified method for their determination. There are plenty of techniques available in the market that were initially used for colloidal particles (e.g., microscopy, spectroscopy and the recent addition of magnetic resonance), but each of these techniques has a certain degree of uncertainty.Further, sample homogeneity, sample preparation, instrument-operating procedures, and statistical practices are likely to add to the complexity of the problem. In this context, this review attempts to understand the widely-used light-scattering techniques, including their theory, practice and real-world use in determination of NPs in environmental and food applications.     

One-step synthesis of large-aspect-ratio single-crystalline gold nanorods by using CTPAB and CTBAB surfactants

Gold nanorods were prepared in high yields by using a one-step seed-mediated process in aqueous cetyltripropylammonium bromide (CTPAB) and cetyltributylammonium bromide (CTBAB) solutions in the presence of silver nitrate. The diameters of the nanorods range from 3 to 11 nm, their lengths are in the range of 15 to 350 nm, and their aspect ratios are in the range of 2 to 70. The diameters of the Au nanorods obtained from one growth batch in CTPAB solutions decrease as their lengths increase, and their volumes decrease as the aspect ratios increase. The diameters of the Au nanorods obtained from one growth batch in CTBAB solutions first decrease and then slightly increase as their lengths increase, and their volumes increase as the aspect ratios increase. These Au nanorods are single-crystalline and are seen to be oriented in either the [100] or [110] direction under transmission electron microscopy imaging, irrespective of their sizes. To the best of our knowledge, this is the first report of the preparation by using wet-chemistry methods of single-crystalline Au nanorods with aspect ratios larger than 15.     

卟啉及其光电化学研究进展

卟啉及金属卟啉在自然界中广泛存在,其光学、电化学等特性可通过分子结构中多个反应位点进行调控. 随着全球能源环境问题日益凸显,卟啉在太阳能电池、光催化制氢领域的研究成为热点. 本文简介了作者课题组近年来通过国内外合作开展的D-π-A结构卟啉分子结构改性及其对光电化学性质和器件光伏特性影响的进展,并对未来卟啉光电化学研究的发展进行了简要的探讨.     

Fluoroarylphosphines as ligands

This short review concentrates on important aspects of fluoroarylphosphines, in particular their synthesis, ligand properties and chemical and catalytic properties of their complexes. Although the electronic, steric and chemical properties of fluoroarylphosphines have been known for 30 years, their use as ligands for homogeneous catalysis and in the synthesis of elaborate multidentate ligands has occurred more recently. The number of recent reports suggests that their importance is growing.     

Study of the polyphenol content of red and white grape varieties by liquid chromatography-mass spectrometry and its relationship to antioxidant power

There is considerable interest in the analysis of phenolic compounds due to their involvement in the organoleptic characteristics of foods and drinks, and their contribution to protection against cardiovascular diseases and cancers through their antioxidant activity. This article describes studies of the polyphenol content, both total (by means of the Folin-Ciocalteu method) and individual (by means of HPLC, LC-MS and LC-MS-MS) and the antioxidant power, of six varieties of grape over the course of their maturation. A good correlation is found to exist between the total polyphenol content of the samples and their antioxidant power, and both seem diminish along the maturation.     

聚乙二醇及其单醚在咪唑N-烷基化反应中的应用

本文报道了在咪唑N-烷基化反应中以聚乙二醇(PEG)及其单醚作为相转移催化剂合成C_4-C_(16) N-烷基咪唑及咪唑N-烷基衍生物的新方法。该法反应条件温和,操作简便,收率可达70％左右。测定了N-烷基咪唑化合物的物理性能,~1H NMR和红外光谱,并讨论了反应条件和烷基化试剂的碳链结构对反应的影响。     

Multi‐Stimuli‐Responsive Polymeric Materials

Stimuli‐responsive materials are of immense importance because of their ability to undergo alteration of their properties in response to their environment. The properties of such materials can be tuned by subtle adjustments in temperature, pH, light, and so forth. Among such smart materials, multi‐stimuli‐responsive polymeric materials are of pronounced significance as they offer a wide range of applications and their properties can be tuned through several mechanisms. Here, we aim to highlight some recent studies showcasing the multi‐stimuli‐responsive character of these polymers, which are still relatively little known compared to their single‐stimuli‐responsive counterpart.     

二氧化钛纳米材料及其能源应用

简要介绍了二氧化钛纳米材料的合成、性质、改性及其在能源方面的应用.其中合成方法包括溶胶凝胶、水/溶剂热、氧化、沉积和超声/微波助合成法:性质包括结构和热力学以及电学和光学性质;改性包括掺杂和敏化;应用包括光催化、光伏打和光解水.