Synthesis,Crystal Structure,and Studies on Mechanism of D-π-A Ferrocene Derivative

Russian Journal of Coordination Chemistry - Microwave-assisted solvent-free synthesis of new (D-π-A) chromogenes, 2-ferrocenyl-1,1-dicyanobuta-1,3-diene derivatives (II), have been...     

紫外拉曼光谱研究FeAlPO_4-5分子筛的合成机理

利用紫外共振拉曼光谱和紫外-可见漫反射光谱对不同铁含量的 FeAlPO4-5 分子筛进行了研究. 结果表明, FeAlPO4-5 分子筛的骨架铁有 4 个特征的拉曼谱峰, 分别位于 630, 1060, 1140 和 1210 cm?1. 当凝胶中 Al/Fe 比小于 380 时, 只有一部分铁离子可以进入分子筛形成四配位的骨架铁物种; 而另一部分则以骨架外六配位的铁物种存在, 其特征拉曼谱峰位于 285 cm?1. 结合紫外拉曼光谱、紫外-可见漫反射光谱和 X 射线衍射研究了 Al/Fe 比为 760 时 FeAlPO4-5 分子筛的晶化过程. 结果发现, 在分子筛晶化前, 铁物种以六配位的形式存在, 它为分子筛前体中的一维链状磷酸铝添加了一个惰性端基, 六配位的 Fe-O 键不利于它与其它磷酸铝物种发生反应; 当分子筛开始晶化时, 带有铁离子端基的磷酸铝链与其它磷酸铝链进一步反应形成分子筛骨架. 同时, 六配位的铁离子和邻近的磷酸铝物种反应转化为四配位的骨架铁物种.     

Review: Advances in the Determination of Peroxides by Optical and Spectroscopic Methods

This review focuses on the recent advances made in the field of organic peroxide analysis using spectroscopic methods. In this area, optical techniques and mass spectroscopy play a dominant role. Emphasis has been given to peroxides of great practical significance, such as lipid hydroperoxides, antimalarial peroxides, peroxide-based explosives, and industrially relevant peroxides. The discussion includes current challenges and trends in each of these groups. The underlying chemical principles of the described methods are briefly discussed. All the advances are categorized by branches of spectroscopy, and example applications are outlined. The scope of this paper is restricted to the most significant advances published between 2003 and mid-2013.     

老人与海内部版——睾酮素始末

以"老人与海"的故事为背景,在老人锻炼和捕鱼的故事中科普肌肉训练中睾酮素的作用机理、变化情况及其生理功能,并给热爱健身的读者一些科学的指导。     

Derivative Spectrophotometric Analysis of Oestradiol Esters,Testosterone and Progesterone in Oily Injections

Abstract

The use of derivative and difference-derivative spectrophotometry for the determination of certain drugs in oily injection is presented. The method is illustrated by the determination of oestradiol valerate, oestradiol dipropionate, oestradiol benzoate, testosterone propionate and progesterone in their oily injections. This method is simple, rapid and accurate. The results obtained are reasonably reproducible with a coefficient of variation less than 2%.     

AM-6分子筛的快速合成及原子线形成机理研究

报道了一种4 h快速合成AM-6分子筛的方法,考察了凝胶中K+含量和起始凝胶碱度对AM-6分子筛纯度以及晶化度的影响.结果表明,向合成体系中引入适量K+可以抑制杂相的生成,在n(K+)/n(V4+)=3和pH=12.5条件下,制备的样品为纯相且晶化度最高.结合紫外-可见吸收光谱和紫外拉曼光谱研究了AM-6分子筛的形成过...     

Spectroscopic,conformational analysis,structural benchmarking,excited state dynamics,and the photovoltaic properties of Enalapril and Lisinopril

There have been numerous attempts to theoretically design a better photovoltaic property with much interest on how to improved absorption and emission parameters of most reactive compounds in respect to dye – sensitized solar cells (DSSCs). This is regardless of the promising futures of the photovoltaic properties. However, for such effective design, it is necessary to understand the electronic and photophysical properties of the dye systems. Herein detailed density functional theory (DFT) and time – dependent DFT (TD-DFT) investigation of the excited state characteristics and the influence of various solvents: water, acetone, ethanol and chloroform on the photophysical properties of enalapril and lisinopril were investigated along with the experimental spectral (UV–vis and FT-IR) analysis. The electronic structure calculations were conducted using the 6–311++G(d,p) basis set in combination with B3LYP, M06-2X, and ?B97XD DFT functionals for the structural benchmarking investigations of the studied compounds. Results of the excitation electronic analysis of enalapril was observed to have wavelength absorption in the order gas > chloroform > ethanol > water which correspond to 229.19, 228.81, 228.85, 229.03 nm respectively while Lisinopril have the order of chloroform > gas > water > ethanol which present ethanol have the highest transition energy. In all the studied structured, the transition assignment corresponds to π $\to$ π* all corresponding to the Frank -Condon local excitation. It can be inferred from the photovoltaic properties that among the studied compounds in four different phases enalapril have the highest oscillator strength, but the values of light-harvesting efficiency (LHE) varies and show greater stability in Lisinopril. Lisinopril was observed to have the highest value of $V_{OC}$ compared to Enalapril this further confirmed the result obtained from the frontier molecular orbitals.     

Moenomycin Biosynthesis: Structure and Mechanism of Action of the Prenyltransferase MoeN5

The structure of MoeN5, a unique prenyltransferase involved in the biosynthesis of the antibiotic moenomycin, is reported. MoeN5 catalyzes the reaction of geranyl diphosphate (GPP) with the cis‐farnesyl group in phosphoglycolipid 5 to form the (C₂₅) moenocinyl‐sidechain‐containing lipid 7 . GPP binds to an allylic site (S1) and aligns well with known S1 inhibitors. Alkyl glycosides, glycolipids, can bind to both S1 and a second site, S2. Long sidechains in S2 are “bent” and co‐locate with the homoallylic substrate isopentenyl diphosphate in other prenyltransferases. These observations support a MoeN5 mechanism in which 5 binds to S2 with its C6–C11 group poised to attack C1 in GPP to form the moenocinyl sidechain, with the more distal regions of 5 aligning with the distal glucose in decyl maltoside. The results are of general interest because they provide the first structures of MoeN5 and a structural basis for its mechanism of action, results that will facilitate the design of new antibiotics.     

Influence of Hydration on the Structure and Interactions of Ethaline Deep-Eutectic Solvent: A Spectroscopic and Computational Study

Deep-eutectic solvents (DESs) are regarded as alternative green solvents to ionic liquids. In this work we report the structural properties and hydrogen bonding (H-bonding) interactions of an aqueous DES system. The used DES, ethaline (ETH), is composed of choline chloride and ethylene glycol (EG) in 1 : 2 molar ratio. The investigations were carried out by FTIR spectroscopy combined with quantum chemical calculations. Excess spectroscopy and two-dimensional correlation spectroscopy (2D-COS) were used to explore the data in detail. The results showed that, upon mixing, ETH transforms to EG dimers and trimers and D₂O clusters transform to various ETH-D₂O complexes. Theoretical calculations show that water molecules insert between the anion and cation of ETH, break the strong doubly ionic Cl^{− …} H−O_Ch+ H-bond, share charges of the ions and form H-bond with them, thus modulate the interaction properties of ETH. This study deepens our molecular-level understanding of the system and would shed light on its applications.     

From Molecular Fragments to Crystals: A UV Raman Spectroscopic Study on the Mechanism of Fe‐ZSM‐5 Synthesis

The nucleation process of iron‐exchanged zeolite Fe‐ZSM‐5, from the assembly of distorted tetrahedrally coordinated iron species and silicate rings in the precursor to the final Fe‐ZSM‐5 crystals, as well as variations in the coordination environment of iron, were studied by UV resonance Raman spectroscopy and complementary techniques.

     

Synthesis,Spectroscopic Studies and Keto-Enol Tautomerism of Novel 1,3,4-Thiadiazole Derivative Containing 3-Mercaptobutan-2-one and Quinazolin-4-one Moieties

In this study, a novel 1,3,4-thiadiazole derivative containing 3-mercaptobutan-2-one and quinazolin-4-one moieties (Compound 3) is synthesized by the coupling of 2-amino-1,3,4-thiadiazole-5-(3-mercaptobutan-2-one) (Compound 1) with 2-Phenyl-4H-3,1-benzoxazin-4-one (Compound 2) in one molecule moiety. Compound 3 is found to exist as two types of intra-molecular hydrogen bonding with keto-enol tautomerism characters, which is further confirmed using FTIR, ¹H-NMR, ¹³C-NMR, mass spectrometer, and UV-Visible spectra. The ¹H-NMR and UV-Visible spectra of Compound 3 are investigated in different solvents such as methanol, chloroform, and DMSO. Compound 3 exhibits keto-enol tautomeric forms in solvents with different percentage ratios depending on the solvent polarity. The ¹H-NMR and UV-Visible spectral results show that Compound 3 favors the keto over the enol form in polar aprotic solvents such as DMSO and the enol over the keto form in non-polar solvents such as chloroform. The ¹³C-NMR spectrum gives two singles at δ 204.5 ppm, due to ketonic carbon, and δ 155.5 ppm, due to enolic carbon, confirming the keto-enol tautomerism of Compound 3. Furthermore, the molecular ion at m/z 43 and m/z 407 in the mass spectrum of Compound 3 and fragmentation mechanisms proposed reveal the existence of the keto and enol forms, respectively.     

Structure and Mechanism of Action of the Active Center of Yeast Pyruvate Decarboxylase

Kinetic studies have shown that the two low molecular-weight components of yeast pyruvate decarboxylase (thiamine pyrophosphate and Mg^2⊕ ions) first add rapidly and reversibly to the apoenzyme in binary equilibria. The resulting adduct then “cyclizes” in a rate-determining, practically irreversible reaction to form the thermodynamically stable holoenzyme. These results were supplemented and extended by the testing of numerous analogues of thiamine pyrophosphate in enzyme experiments and then used for the interpretation of the enzyme reaction.     

综合化学实验：二苯并噻吩衍生物的合成、结构与性质

介绍了一个综合化学实验,涉及有机化合物的合成、结构以及荧光性质的表征。该实验将大学有机化学的基础知识、基本实验技能与学术研究的前沿相结合。在实验教学中融入荧光发光体的知识,能够引导学生深入理解荧光发光体的相关概念及理论,显著激发学生学习的兴趣,还可以加深学生对有机合成化学基础知识的理解,获取前沿知识,同时熟悉大型仪器,培养学生理论联系实际的能力以及综合实验技能。     

Cd(Ⅱ)双苯吡唑基吡啶-草酸混配合物的合成、结构与性质

合成了Cd(Ⅱ)与类蝎型吡唑衍生物和草酸的混合配体的配合物[Cd2(HL)2(ox)]·1.5H2O(H2L=2,6-二(5-苯基-吡唑-3-基)吡啶,H2ox=草酸)。 通过元素分析、红外光谱、紫外光谱、X射线粉末衍射(PXRD)和X射线单晶结构分析确定了配合物的结构。 配合物晶体属于三斜晶系、P-1空间群,Cd(Ⅱ)是六配位,由一个ox2-基中的2个O原子和来自2个HL-中的4个N原子配位,构成变形八面体配位构型,而相邻Cd(Ⅱ)原子间均通过HL-上的N原子和草酸根分别连接形成2条互不相交的一维无限链状结构。 性质测试结果表明,该配合物具有良好的热稳定性和荧光特性,对环己烷氧化反应也具有一定的催化活性。     

Thermal and Spectroscopic Studies on the Decomposition of Some Aminoguanidine Nitrates

Diaminoguanidine nitrate (DAGN) and triaminoguanidine nitrate (TAGN),potential energetic materials in emerging propulsion technology with high mass impetus at low isochoric flame temperature have been studied as regards kinetics and mechanism of thermal decomposition using thermogravimetry (TG), differential thermal analysis (DTA),infrared spectroscopy (IR) and hot stage microscopy. Kinetics of thermolysis has been followed by isothermal TG and IR. For the initial stage of thermolysis of DAGN the best linearity with a correlation coefficient of 0.9976 was obtained for the Avrami-Erofe'evequation, n=2, by isothermal TG. The activation energy was found to be 130 kJ mol^–1 and logA=11.4. The initial stage of thermolysis of TAGN also obeyed the Avrami-Erofe'ev equation, n=2, with a correlation coefficient of 0.9975by isothermal TG and the kinetic parameters are E=160.0 kJ mol^–1 and logA=16.0. High temperature IR spectra showed exquisite preferential loss in intensity of the NH₂, NH, N–N stretching and CNN bending. Spectroscopic and other results favour deamination reaction involving the rupture of the N–N bond as the primary step in the thermal decomposition. This revised version was published online in July 2006 with corrections to the Cover Date.     

一种新型芒柄花素衍生物4′-甲氧基-7-乙氧基异黄酮的合成、晶体结构及量子化学研究

以芒柄花素为先导化合物,合成了一种新型的衍生物4′-甲氧基-7-乙氧基异黄酮,通过X射线单晶衍射法对它的结构进行了表征.为了研究化合物的电子结构,在其晶体结构基础上进行了量子化学计算.采用密度泛函理论(DFT),B3LYP方法,对其进行优化,优化结果与实验吻合良好并且被用于后面前线分子轨道及自然电荷布居分析的计算.     

Chamomile: A Review of Its Traditional Uses,Chemical Constituents,Pharmacological Activities and Quality Control Studies

Matricaria chamomilla L. (MC) and Chamaemelum nobile (L.) All. (CN) are two varieties of Chamomile. These herbs have been used for thousands of years in Greece, Rome and ancient Egypt. Chamomile has been used for the treatment of stomach problems, cramps, dermatitis, and minor infections. The purpose of this study was to introduce the botanical characteristics and geographical distribution, traditional uses, chemical constituents, pharmacological activities, toxicity studies and quality control studies, and lay a theoretical foundation for the rational development and utilization of chamomile. This review powered that chemical constituents include flavonoids, coumarins, volatile oils, terpenes, organic acids, polysaccharides, and others. These compounds possess anticancer, anti-infective, anti-inflammatory, antithrombotic, antioxidant, hypolipidaemic, hypoglycaemic, antihypertensive, antidepressant, neuroprotective activities, among others. Chamomile is a widely used herb in traditional medicine. It brings great economic value due to its numerous pharmacological effects and traditional uses. However, more toxicity tests should be carried out to confirm its safety. There is need for further research to provide concrete scientific evidence and validate its medicinal properties.     

大学生发Zn、Fe、Ca、Pb与部分膳食营养结构及体智能素质相关关系的初步研究

通过原子吸收光谱法及调查分析法对不同年级100名大学生头发中Zn、Fe、Ca、Pb与部分膳食营养结构状况和体智能素质进行了测定，并作了相关关系的初步研究，结果表明学生的膳食营养结构是否合理，在一定程度上影响着他们体内有关必需元素含量的平衡，进而影响着他们的生理及智力发育。