什么是元素有机化学?

什么是元素有机化学？单自兴（武汉大学化学系４３００７２）元素有机化学是化学科学中发展最迅速的分支学科之一。元素有机化学的研究，提出一系列新概念、新结构、新理论，丰富和强化了化学科学的理论宝库；元素有机化学的研究，导致众多新试剂、新催化剂、新反应、新方...     

1992年有机化学回顾（中）

金属有机化学 Ⅰ.催化剂 ⒈烯烃聚合 Brintzinger和Kaminsky将ansa—金属茂用于Ziegler—Natta均相烯烃聚合反应之后使这一反应在技术上趋于成熟。Hochst公司的Spaleck和慕尼黑工业大学的 Herrmann及他们的同事们一起对催化剂(1)进行了艰难困苦的合成与结构研究并获成功[Spaleck,W.;Autberg,M.;Rohrmann,J.;Winter,A.;Bachmann,B.;     

漫谈金属有机化学

引言金属有机化学和配位化学分别是从有机化学和无机化学两个领域中发展起来而又密切联系的学科,目前已汇成一股洪流,成为近代化学前沿领域之一.它的发展打破了传统的有机化学和无机化学的界限,金属有机化学已成为有机化学中主流之一,它的发展又与理论化学、合成化学、催化、结构化学、生物无机化学、高分子科学等交织在一起. 什么是金属有机化合物?凡是化合物中含有碳-金属键的都是金属有机化合物.不言而喻,根据我国化学名词命名法,凡有金字偏旁的元素与碳成键的化合物,当然属于金属有     

"21世纪中国有机化学发展战略”研讨会纪要

由国家自然科学基金委化学部与中国科学院化学部主办、中国科学院上海有机化学研究所协办的“2 1世纪中国有机化学发展战略”研讨会于 2 0 0 1年4月 2 0— 2 1日在上海青浦举行。国家科技部副部长程津培教授、国家自然科学基金委副主任朱道本院士、国家自然科学基金委化学部主任张礼和院士出席研讨会并作了发言。来自中国科学院、教育部等系统的 80多位专家学者参加了会议 ,其中包括 1 1位中国科学院、中国工程院院士 ,6位来自香港、台湾地区的教授 ,一位来自美国的大学教授。在两天的研讨会中 ,与会专家深入探讨了中国有机化学在新世纪之初…     

1987年有机化学的回顾（下）

新分子-老分子对于低分子量有机化学领域,特别是碳氢化合物化学,面对生物化学的发展,曾预言它将逐渐消亡。但在1987年内又有许多有趣的报道。这证明碳氢化合物仍是有生命力的。碳氢化合物化学在某种方式上还起着指导作用:构成化合物时,碳原子的连结可能是十分难解决的问题,而这正是碳氢化学家们设法解决的。这些问题在自然界中也随时可见。另一方面,由于已发展了很多奇异碳氢化合物的合成方法,所以,如今在很多情况下,已可按满意的得率合成稳定或不太稳定的物质,常常还可引入官能团,并且推动了这     

有机反应进程解析——VBCM模型

有机反应进程解析,即考察从反应物经由过渡状态到产物的转变过程中,结构的改变和所伴同的能量变化,是物理有机化学的主要研究课题之一。这方面的主要理论有Hammond假设(1955)、Marcus反应速率理论(1964)等;前者是定性的,后者是定量的。70年代后期,主要由以色列的A.Pross和S.S.Shaik发展起来一个新的定性的理论,即CM模型(CM是configuration mixing——“组态混合”的缩写)。在CM模型中,有关结构的描写,可用价键(共振)法     

介绍一本《有机化学实验》新教材

由上海市教育委员会组编 ,焦家俊编著 ,上海交通大学出版社出版的《有机化学实验》(2 0 0 0年 2月第一版 ) ,是按照国家教育部“面向 2 1世纪应用化学类专业教学内容和课程体系改革”的要求编写的一本有机化学实验教材。该书在编写过程中 ,试图对传统有机化学实验强调实验操作技能训练的教学模式进行改革 ,努力突出“新概念” ,即以实践能力与创新精神培养为目标 ,从学习实验通法入手 ,着力将基本理论学习、综合能力训练及创新精神培养融为一体。　　全书分为以下 3部分 :　　第一部分为反应与制备 ,包括卤化反应、磺化反应、硝化反应、付 …     

有机化学实验教学内容改革与实践

从丰富实验内容、改进基本操作实验,改善实验条件、完善实验内容和将有机化学学科发展前沿研究成果用于有机化学实验教学3方面介绍了有机化学实验教学内容改革的方法。教学实践表明这些方法有利于拓宽学生视野,激发学习兴趣,提高创新能力。     

北京大学有机化学教材建设的历史发展与经验

回顾了北京大学有机化学教材建设的历程,介绍了《基础有机化学》第四版的主要内容和特色。指出教材的建设过程和教材内容、格式的渐进变化要紧跟时代步伐,不断推陈出新,为培养创造性的人才做出贡献。     

Versatility and specificity in flavoenzymes: control mechanisms of flavin reactivity

Flavoenzymes are characterized by their remarkable versatility and strict specificity. The former can be grasped when flavoenzymes are treated as a whole, while the latter refers to each flavoenzyme in which the broad versatility of flavin is specifically controlled. The versatility stems from the variety of the redox, ionic, and electronic states that the flavin ring system can adopt. Versatility of flavoenzymes is reflected in their classification, which has generally been based on substrates and reactions catalyzed. A different classification is presented according to the number of electrons transferred in the reductive and oxidative half reactions. Specificity of each flavoenzyme is understood in terms of the regulatory mechanism of the broad reactive potentiality of flavin. The elements of this regulatory mechanism include hydrogen-bonding network, electrostatic effect, charge-transfer interaction, positioning between a substrate/ligand and flavin, and modulation of resonance hybridization, each of which is explained with relevant examples provided mainly by studies from the author's group.     

Model systems for flavoenzyme activity: recognition and redox modulation of flavin mononucleotide in water using nanoparticles

We have used mixed monolayer protected gold clusters (MMPCs) to provide flavoenzyme model systems with a high affinity and ability to modulate cofactor reduction potential.     

Polymeric model systems for flavoenzyme activity: towards synthetic flavoenzymes

We report the synthesis of a water-soluble flavin polymer using ATRP, whereby the oligoethylene glycol backbone provides both a local hydrophobic environment and redox tuning of the flavin moiety typical of flavoenzyme prototypes.     

Two‐Step Synthetic Route to 10‐Substituted Isoalloxazines

10‐Substituted isoalloxazines were synthesized in two steps starting from 1,2‐phenylenediamine. Monoalkylation of the diamine resulted in 2‐amino‐N‐alkylanilines, which were subsequently condensed with alloxan in boric acid and acetic acid to give 10‐substituted isoalloxazines.     

Identification of inhibitors for UDP-galactopyranose mutase

The flavoenzyme uridine 5'-diphosphate (UDP)-galactopyranose mutase (UGM) plays a key role in the cell wall biosynthesis of many pathogens, including Mycobacterium tuberculosis. Using a synthetic fluorescent ligand, we screened 16 000 compounds in a fluorescence polarization assay. Effective inhibitors of UGM were identified.     

Synthesis and reaction of a new type of 5-deazaflavin with axial and planar chirality

A new type of 5-deazaflavin derivative with axial and planar chirality was synthesized as a flavoenzyme model. A novel optical resolution gave an enantiomeric pair of the 5-deazaflavins 1a,b. Compounds1a,b were optically stable and effectively discriminated PNPH enantiomers in a model reaction of intercoenzyme hydrogen transfer.     

PICOSECOND LASER PHOTOLYSIS STUDIES OF FLUORESCENCE QUENCHING MECHANISMS OF FLAVIN: A DIRECT OBSERVATION OF INDOLE-FLAVIN SINGLET CHARGE TRANSFER STATE FORMATION IN SOLUTIONS and FLAVOENZYMES

Formation of singlet charge transfer (heteroexcimer) states in the course of the fluorescence quenching of lumiflavin and riboflavin tetrabutyrate by indole and N-methylindole have been directly observed by means of time-resolved absorption spectral measurements using a picosecond laser photolysis method. Similar transient spectra have been observed also in the case of a flavoenzyme, D-amino acid oxidase.     

Catalytic Amine Oxidation under Ambient Aerobic Conditions: Mimicry of Monoamine Oxidase B

The flavoenzyme monoamine oxidase (MAO) regulates mammalian behavioral patterns by modulating neurotransmitters such as adrenaline and serotonin. The mechanistic basis which underpins this enzyme is far from agreed upon. Reported herein is that the combination of a synthetic flavin and alloxan generates a catalyst system which facilitates biomimetic amine oxidation. Mechanistic and electron paramagnetic (EPR) spectroscopic data supports the conclusion that the reaction proceeds through a radical manifold. This data provides the first example of a biorelevant synthetic model for monoamine oxidase B activity.     

NAD(P)H‐Independent Asymmetric CC Bond Reduction Catalyzed by Ene Reductases by Using Artificial Co‐substrates as the Hydrogen Donor

To develop a nicotinamide‐independent single flavoenzyme system for the asymmetric bioreduction of C?C bonds, four types of hydrogen donor, encompassing more than 50 candidates, were investigated. Six highly potent, cheap, and commercially available co‐substrates were identified that (under the optimized conditions) resulted in conversions and enantioselectivities comparable with, or even superior to, those obtained with traditional two‐enzyme nicotinamide adenine dinucleotide phosphate (NAD(P)H)‐recycling systems.     

Covalent Attachment of Active Enzymes to Upconversion Phosphors Allows Ratiometric Detection of Substrates

Upconverting phosphors (UCPs) convert multiple low energy photons into higher energy emission via the process of photon upconversion and offer an attractive alternative to organic fluorophores for use as luminescent probes. Here, UCPs were capped with functionalized silica in order to provide a surface to covalently conjugate proteins with surface-accessible cysteines. Variants of green fluorescent protein (GFP) and the flavoenzyme pentaerythritol tetranitrate reductase (PETNR) were then attached via maleimide-thiol coupling in order to allow energy transfer from the UCP to the GFP or flavin cofactor of PETNR, respectively. PETNR retains its activity when coupled to the UCPs, which allows reversible detection of enzyme substrates via ratiometric sensing of the enzyme redox state.