四重氢键调控有机凝胶的宏观自组装

合成了一种带有脲基嘧啶酮(ureidopyrimidinone, UPy)四重氢键单元的甲基丙烯酸酯类单体MAMIS,并用氢核磁(1H-NMR)、红外光谱(FTIR)、电喷雾质谱(ESI-MS)和元素分析确认其结构.以二甲基亚砜(DMSO)为溶剂,基于MAMIS及丙烯酸酯类单体的自由基共聚,合成了一种带有UPy单元的有机凝胶,采用元素分析、红外光谱和扫描电子显微镜(SEM)表征了凝胶的组成及形貌,并采用差示扫描量热仪(DSC)测定了干凝胶的玻璃化转变温度(Tg).与不含UPy单元的凝胶相比,UPy单元的引入显著提高了干凝胶的Tg,但基本不影响凝胶的微观形貌.研究了UPy凝胶在UPy四重氢键驱动下的宏观自组装行为,结果表明UPy凝胶块在甲苯中聚集,在DMSO中分离,该过程可多次重复.随着UPy单元含量的增加及溶剂极性的降低,凝胶块的结合强度逐渐增加,体现出溶剂敏感性.基于四重氢键驱动的宏观自组装,可以实现染料分子在不同凝胶块间的传递.     

高指数晶面裸露的贵金属纳米晶体的合成

由于在高指数晶面上存在高密度的台阶位、扭结位原子等,高指数晶面裸露的贵金属纳米晶体一般表现出优越的物理化学性能,在催化、电化学等方面都有很重要的应用前景．近年来,研究人员围绕高指数晶面的制备进行了大量的工作并取得了一定进展．本文重点从合成制备方法的角度出发,结合本课题组的相关研究,系统总结了现有的有关制备高指数晶面裸露的贵金属纳米晶体的一些最新研究成果．从电化学方法、“帽”式试剂保护法、欠电位沉积原子层保护法、动力学调控、氧化刻蚀溶解再生长法以及模板法等几个方面对现有的高指数晶面裸露的贵金属纳米晶体的制备进行了总结．     

精准宏观超分子组装

宏观超分子组装是近年来超分子科学的新兴研究方向,其本质是表面修饰有大量超分子官能团的宏观构筑基元的界面组装. 由于组装过程中存在较多热力学亚稳态,导致最终产生大量非精准组装体,整体结构有序度低,制约了其在高性能超分子材料方面的应用,因此,如何实现精准宏观超分子组装,构建有序超分子结构,成为了制约宏观超分子组装发展的瓶颈问题之一. 本专论从宏观超分子组装的概念与组装机制出发,根据宏观超分子组装过程的特点,分析阐述了组装体中存在不同界面匹配度的热力学亚稳态的问题;继而,从能量面的角度展开分析,总结和归纳了提高组装结构有序度的精准组装策略,包括：(1)利用组装体热力学稳定性差异,设计各向异性构筑基元诱导目标组装结构的形成,发展自纠错策略提高组装界面匹配度;(2)引入宏观构筑基元的组装动力学设计,使构筑基元发生自驱动运动并通过界面长程力取向,使组装界面达到高度匹配,实现近热力学平衡态的精准组装,直接获得精准结构. 进而,结合精准宏观超分子组装制备的有序结构,我们展望了其在构建组织工程支架方面的应用前景.     

高表面能晶面裸露的金属氧化物微纳米晶体的可控合成

表面结构是影响固体材料物理和化学性质的重要因素,由于高表面能的晶面上存在更多的表面悬挂键等,高表面能晶面裸露的微纳米晶体一般表现出很好的物理和化学活性．近年来,科研工作者针对高能面微纳米晶体材料的制备及性能调控进行了大量的研究工作并取得了一定的进展．本文重点讨论了高能面裸露的金属氧化物半导体微纳米晶体的合成制备方法．主要以本课题组近年在该领域的研究为例,分别从晶体生长过程中的静电作用法、“帽”式试剂保护法、过饱和度调控法、动力学调控法及选择性化学刻蚀法等几个方面对高表面能晶面裸露的金属氧化物微纳米晶体的制备进行了系统的总结．     

硝酸分解磷矿的宏观动力学研究

在间歇反应器中 ,反应温度为 30～ 6 0℃ ,硝酸初始浓度 30～ 5 4 % ,磷矿初始粒径 0 .375～ 1.0 75毫米 ,搅拌强度 4 0 0转 分的条件下研究了硝酸分解磷矿的反应过程机理及宏观动力学。结果表明 ,磷矿分解速率及转化率随着搅拌强度、反应温度、硝酸浓度和颗粒细度的增加而增加 ;氢离子通过液膜的扩散传质是该过程的速率控制步骤。应用固体粒径减小的缩芯模型 ,将上述各影响因素的实验数据回归得到如下的宏观动力学模型 :1- (1-xB) 2 3=8.36 6exp - 6 .198× 10 3RT c1 .31 1AO R- 0 .1 0 91S lnτ活化能Ea=6 .198kJ mol,属液膜扩散传质控制     

碳纳米管宏观条带的原位制备

采用化学气相沉积法(CVD),以二甲苯为碳源,二茂铁为催化剂,在涂有SiO₂薄膜的不锈钢基底上,原位制备出了碳纳米管宏观条带。使用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和拉曼光谱(Raman)对样品形貌和结构进行了表征。结果显示：合成的碳纳米管条带宽度为20～100 μm,厚度10～30 μm,长度可达6 mm;条带由大量多壁碳纳米管沿轴向密实排列组成。对其形成机制进行了初步探讨。     

KAl(SO4)2 · 12H2O as a Recyclable Lewis Acid Catalyst for Synthesis of Spirooxindoles in Aqueous Media

A simple and efficient procedure for the synthesis of spirooxindole has been described that employs a three-component condensation reaction in one pot using isatin, active methylene reagent, and 1,3-dicarbonyl compounds in an aqueous medium.     

Evaluation of Viscosity-Molecular Weight Constant (K), Short Range Parameter (A) and Long Range Parameter (B) of Dextran in Polar Solvents

Abstract

The viscosity-molecular weight constant (K), the short range parameter (A) and long range parameter (B) have been evaluated in binary mixture of Dextran of three different molecular weights in three different solvents i.e., distilled water, 1(N) NaOH and 1(N) KOH, at temperatures ranging from 25°C to 50°C. The study reveals that the viscosity-molecular weight constant (K) decreases with increase in temperature for polar solvents. The short range parameter (A) shows the same trend as shown by K and the long range parameter (B) exhibits no definite trend with the variation of temperature.     

荧光法对光诱导野生型肌红蛋白和突变体(D44K)去氧的对照研究

用荧光法对光诱导野生型肌红蛋白(Mb)和突变体(D44K)去氧的过程进行对照研究。发现430nm是研究Mb(WT)和Mb(D44K)光照去氧的最佳激发波长。430nm激发时,Mb(D44K)在597.9nm和628.8nm处出现两个荧光发射峰,不同于Mb(WT)仅在597nm处出现一个荧光发射峰。经研究证明,628.8nm处荧光峰是Mb3 -H2O型中的H2O峰。光照也使此峰的荧光强度下降,但比去氧的速率慢。研究发现,597nm处Mb(D44K)的荧光效率比Mb(WT)的荧光效率低。传能实验表明Mb表面44位氨基酸由天冬氨酸突变为赖氨酸后,不影响Mb(D44K)中色氨酸和酪氨酸残基传递给铁卟啉的荧光效率,但使Mb(D44K)中色氨酸和酪氨酸残基的荧光效率变高。     

Alum (KAl(SO4)2 · 12H2O): An Efficient and Inexpensive Catalyst for the One-pot Synthesis of 1,3,4-Oxadiazoles under Solvent-Free Conditions

Summary. Alum (KAl(SO₄)₂ · 12H₂O) catalyzed the efficient synthesis of mono- and disubstituted 1,3,4-oxadiazoles by the condensation of acyl hydrazides with orthoesters under solvent-free conditions at 100°C. This methodology offers significant improvements for the synthesis of oxadiazoles with regard to the yield of products, simplicity in operation, inexpensive reagents, and green aspects by avoiding toxic catalysts and solvents.     

Alum-Catalyzed Domino Synthesis of 12-Substituted-8,9,10,12-tetrahydrobenzoxanthen-11-ones Under Solvent-Free Conditions

Alum is found to catalyze efficiently the one-pot, three-component condensation of aldehydes, α/β-naphthol, and dimedone to afford various 12-substituted-8,9,10,12-tetrahydrobenzoxanthen-11-ones in excellent yields. The use of alum catalyst and the solvent-free conditions make this method simple, convenient, eco-friendly, and cost-effective.     

新型吡啶苯磺酰胺联喹啉基异羟肟酸类PI3K/HDAC双靶点抑制剂的设计、合成和生物活性研究

多靶点药物已成为一种有广阔前景的药物,特别是对抗肿瘤药物的研发.基于候选药物GSK2126458和上市药物Vorinostat的结构特点,设计并合成了一系列新型的磷脂酰肌醇3-激酶(PI3Ks)和组蛋白脱乙酰酶(HDACs)双重抑制剂.生物活性研究发现,化合物GYB-4对PI3Kα和HDAC1的IC50分别为1.0和4.2nmol/L;化合物GYB-5对PI3Kα和HDAC1的IC50分别为1.3和4.8nmol/L.对所有化合物在HCT116,PC3和A2780细胞株上进行了增殖抑制活性研究,相关的构效关系研究将为PI3K和HDAC双靶点抑制剂的进一步优化提供思路.     

Universality behaviour for polarity formation in channel-type inclusion compounds

A statistical investigation based on a Markov chain theory of polarity formation applied to channel-type inclusion compounds loaded with both dipolar A–π–D and non-polar N–π–N (N: A or D) guests is presented. The key parameters effecting polarity formation are identified and their effects are explored. A number of paradoxes are set out and an attempt to explain the mechanisms behind them is made: dependence of macroscopic polarity on orientational selectivity induced by intermolecular interactions, tuning of polarity through (i) the concentration of non-polar guest and (ii) growth temperature. An erratum to this article can be found at     

A new tripodal anion receptor with selective binding for H2PO4 and F ions

The anions binding properties of the pyrrole-based tripodal anion receptor 1 were studied by X-ray crystallography, ¹H NMR, and ESI-MS. It revealed that this new tripodal receptor has a preference for binding H₂PO₄⁻ and F⁻ ions.     

Method for performing LCAO band structure calculations in crystalline solids: Application to rubidium

In this work we present a method for performing LCAO (linear combination of atomic orbitals) band structure calculations (tight binding) in crystalline solids. In the first part of the article we apply group theoretical methods to the establishment of a least‐squares scheme for the calculation of the matrix of the crystal potential: This scheme is based on a well‐defined choice of independent parameters for the Bloch vector‐dependent matrix elements and on the considerations of the symmetries between these independent parameters and their Fourier coefficients. In the second part of this work we deal with the representation of the matrices of the identity operator and of the operator of the kinetic energy by linear combinations in terms of two center integrals: We express these linear combinations by a closed formula, which can be easily programmed on a computer, and we mention a method by which the two center integrals can be evaluated numerically fast and accurately. Finally we apply our theory to the derivation of numerical results: We determine the electronic states and the high‐momentum components of Compton rates in the alkali metal rubidium and we compare the results obtained with those of augmented plane‐wave (APW) calculations. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 78: 212–225, 2000