抗凝血生物材料的合成研究：V.聚醚氨酯表面肝素化的新途径

本文报道聚醚氨酯表面肝素化的新途径：用聚醚氨酯预聚体，对－氯甲基苯乙烯、甲基丙烯酸甲酯三元共聚的方法，在聚氨酯链上导入活性氯甲基，氯甲基经三乙胺季铵化后，以离子键将肝素固定在共聚物表面。抗凝血初步试验表明，该途径相当有效。     

聚对氯甲基苯乙烯季铵化反应动力学的研究

 本文主要研究聚对氯甲基苯乙烯同第三胺进行季铵化反应的动力学。结果表明:三乙胺、三丁胺以及吡啶等与聚对氯甲基苯乙烯的反应符合二级反应动力学方程式: f(x)=1/a-b ln[b(a-x)/a(b-x)]=Kt 第三胺在这个反应中的活性有这样的次序:三乙胺>三丁胺>吡啶》N,N-二甲苯胺、对-溴-N,N-二甲苯胺。其中,前三者的反庠活化能分别为12.92kcal/mol、14.57kcal/mol及19.13kcal/mol,而后二者与聚对氯甲基苯乙烯在80℃下几乎不发生反应。     

抗凝血生物材料的合成研究 Ⅴ．聚醚氨酯表面肝素化的新途径

本文报道聚醚氨酯表面肝素化的新途径：用聚醚氨酯预聚体、对一氯甲基苯乙烯、甲基丙烯酸甲酯三元共聚的方法，在聚氨酯链上导入活性氯甲基，氯甲基经三乙胺季控化后以离子键将肝素固定在共聚物表面。抗凝血初步试验表明，该途径相当有效。     

聚对氯甲基苯乙烯季铵化反应动力学的研究

本文主要研究聚对氯甲基苯乙烯同第三胺进行季铵化反应的动力学。结果表明:三乙胺、三丁胺以及吡啶等与聚对氯甲基苯乙烯的反应符合二级反应动力学方程式: f(x)=1/a-b ln[b(a-x)/a(b-x)]=Kt 第三胺在这个反应中的活性有这样的次序:三乙胺>三丁胺>吡啶》N,N-二甲苯胺、对-溴-N,N-二甲苯胺。其中,前三者的反庠活化能分别为12.92kcal/mol、14.57kcal/mol及19.13kcal/mol,而后二者与聚对氯甲基苯乙烯在80℃下几乎不发生反应。     

水溶性两性纤维素衍生物──Ⅰ.羧甲基纤维素的季铵化

以羧甲基纤维素(CMC)为原料、3-氯-2-羟两基三甲基氯化铵(CHPAC)为季铵化剂,合成了一系列水溶性两性纤维素衍生物.研究了CMC季镇化反应的主要影响因素,发现不同的原料羧甲基取代度、反应用碱量、CHPAC用量及反应介质组成对CMC季铵取代度和CMC季铵化反应效率均有不同的影响,同时对原料CMC及其产物的IR、X光衍射和DSC谱图与溶液粘性行为进行了研究.     

带有苄基二甲基γ-硅丙基氯化铵侧基的聚硅氧烷的合成

通过γ－氯丙基甲基硅氧烷－二甲基硅氧烷共聚物和Ｎ,Ｎ－二甲基苄基胺的季铵化反应合成了带有苄基二甲基γ－硅丙基氯化铵侧基的聚硅氧烷。通过季铵化反应过程中γ－氯丙基转化程度随时间的变化以及影响该季铵化速率的各种因素的研究,表明该季铵化反应在反应的初期基本遵循二级反应速率定律,提高反应物的浓度、采用与反应物有适当相溶性的高极性溶剂,以及提高反应温度均能加速季铵化反应。     

聚苯乙烯型双季铵树脂的制备及性能研究

三乙烯二胺和四甲基乙二胺与氯甲基聚苯乙烯反应,得到同时含有季铵和叔胺的强-弱碱型树脂,再用碘甲烷季铵化叔胺,制备聚苯乙烯双季铵树脂;另一种方法是将二甲基苄胺型叔胺树脂用4-溴丁基三甲基溴化铵季铵化引入4碳链双季铵基团。反应结果表明,两类强弱碱基树脂的季铵化反应结果并不理想,二甲基苄胺型叔胺树脂季铵化反应的转化率最高为36%。考察了这些新型双季铵树脂的热稳定性及对水溶液中有机酸(如苯磺酸和对-硝基苯乙酸)的吸附、脱附性能。     

水溶性两性纤维素衍生物Ⅰ.羧甲基纤维素的季铵人

以羧甲基纤维素（ＣＭＣ）为原料、３－氯－２－羟丙基三甲基氯化铵（ＣＨＰＡＣ）为季铵化剂，合成了一系列水溶性两性纤维素衍生物，研究了ＣＭＣ季铵化反应的主要影响因素，发现不同的原料羧甲基取代度、反应用碱量、ＣＨＰＡＣ用量及反应介质组成对ＣＭＣ季铵取人度和ＣＭＣ季铵化反应效率均有不同的影响，同时对原料ＣＭＣＭ及其产物的ＩＲ、Ｘ光射射和ＤＳＣ谱图与溶液粘性行为进行了研究 。     

钒电池用季铵化杂萘联苯聚芳醚酮酮阴离子交换膜

以氯甲基辛醚为氯甲基化试剂, 对杂萘联苯聚芳醚酮酮(PPEKK)进行改性, 制备了氯甲基化杂萘联苯聚芳醚酮酮(CMPPEKK). 考察了氯甲基辛醚用量对氯甲基化程度的影响. ¹H NMR表明氯甲基成功引入到聚合物结构中. 采用溶液法制备了CMPPEKK基膜, 然后将其进行三甲胺胺化, 制备了季铵化杂萘联苯聚芳醚酮酮(QAPPEKK)阴离子交换膜. 表征了QAPPEKK的基本性能: 离子交换容量, 含水率, 面电阻. QAPPEKK膜的含水率随离子交换容量增加而升高, 面电阻随离子交换容量的增加而降低. 将QAPPEKK膜应用于全钒液流电池(VRB)中, 电池的能量效率达到85.0%, 电流效率为98.5%, 电压效率为86.3%.     

溴化四丁铵催化苯乙烯一步合成苯乙烯环状碳酸酯

以溴化季铵盐为催化剂, 通过苯乙烯的环氧化和CO2的加成反应一步直接合成出苯乙烯环状碳酸酯, 详细考察了催化剂的用量、氧化剂的种类、反应温度、反应时间和CO2压力等因素对反应主产物收率的影响. 结果表明, 以溴化四丁铵为催化剂, 于80 ℃和1 MPa CO2下反应6 h, 环状碳酸酯的收率达到38%, 这是季铵盐阳离子和亲核性阴离子协同催化的结果.     

The influence of hydrogen bonding on the physical properties of ionic liquids

Potential applications of ionic liquids depend on the properties of this class of liquid material. To a large extent the structure and properties of these Coulomb systems are determined by the intermolecular interactions among anions and cations. In particular the subtle balance between Coulomb forces, hydrogen bonds and dispersion forces is of great importance for the understanding of ionic liquids. The purpose of the present paper is to answer three questions: Do hydrogen bonds exist in these Coulomb fluids? To what extent do hydrogen bonds contribute to the overall interaction between anions and cations? And finally, are hydrogen bonds important for the physical properties of ionic liquids? All these questions are addressed by using a suitable combination of experimental and theoretical methods including newly synthesized imidazolium-based ionic liquids, far infrared spectroscopy, terahertz spectroscopy, DFT calculations, differential scanning calorimetry (DSC), viscometry and quartz-crystal-microbalance measurements. The key statement is that although ionic liquids consist solely of anions and cations and Coulomb forces are the dominating interaction, local and directional interaction such as hydrogen bonding has significant influence on the structure and properties of ionic liquids. This is demonstrated for the case of melting points, viscosities and enthalpies of vaporization. As a consequence, a variety of important properties can be tuned towards a larger working temperature range, finally expanding the range of potential applications.     

抗凝血生物材料研究 Ⅵ. 聚乙烯的表面肝素化

通过聚乙烯膜表面的臭氧活化及其随后与甲基丙烯酸环氧丙酯（ＧＭＡ）的接枝共聚、α，ω 二氨基聚氧乙烯（ＪｅｆａｍｉｎｅＥＤ ６００、ＥＤ ９００、ＥＤ ２００１）的亲核开环反应以及在碳二亚胺（ＥＤＣ）缩合剂存在下与肝素的缩合反应，可对聚乙烯膜表面进行高效的肝素共价固定化，其中ＪｅｆａｍｉｎｅＥＤ ６００所固定的肝素浓度可高达１３６μｇ／ｃｍ２，材料抗凝血性也最好     

Covalent heparin modification of a polysulfone flat sheet membrane for selective removal of low-density lipoproteins: a simple and versatile method

A simple, convenient and economical method for the heparinization of PSf membranes is described, with the aim of preparing an LDL adsorber for simultaneous LDL apheresis and hemodialysis. An atmospheric pressure glow discharge generator is used to activate the PSf membrane surface, with subsequent chemical binding of heparin in the presence of EDC and NHS. ATR-FTIR spectroscopy and XPS measurements confirm successful surface modification. The PSf-Hep membrane shows good blood compatibility, with a relatively low amount and normal morphology of adherent platelets. ELISA results indicate that the PSf-Hep membrane exhibits excellent selective affinity for LDL in single and binary protein solutions, suggesting potential applications in hemodialysis with simultaneous LDL removal.     

Ionic hydrogen bonds controlling two-dimensional supramolecular systems at a metal surface

Hydrogen-bond formation between ionic adsorbates on an Ag(111) surface under ultrahigh vacuum was studied by scanning tunneling microscopy/spectroscopy (STM/STS), X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS), and molecular dynamics calculations. The adsorbate, 1,3,5-benzenetricarboxylic acid (trimesic acid, TMA), self-assembles at low temperatures (250-300 K) into the known open honeycomb motif through neutral hydrogen bonds formed between carboxyl groups, whereas annealing at 420 K leads to a densely packed quartet structure consisting of flat-lying molecules with one deprotonated carboxyl group per molecule. The resulting charged carboxylate groups form intermolecular ionic hydrogen bonds with enhanced strength compared to the neutral hydrogen bonds; this represents an alternative supramolecular bonding motif in 2D supramolecular organization.     

Tribochemical reaction dynamics of phosphoric ester lubricant additive by using a hybrid tight-binding quantum chemical molecular dynamics method

To study the atomistic behavior of the phosphoric ester molecule on the nascent Fe surface under boundary lubrication conditions, we adopted a hybrid tight-binding quantum chemical molecular dynamics method. First, we investigated chemical interactions between phosphoric ester and the nascent Fe surface. Phosphoric ester was shown to interact with the nascent Fe surface, forming both covalent and ionic bonds. Formation and dissociation dynamics of covalent bonds during tribochemical reaction was clearly observed during the simulation. The effect of friction condition on the tribochemical reaction dynamics was then studied, and it was indicated that friction would influence the formation and the dissociation of covalent bonds. By using a hybrid tight-binding quantum chemical molecular dynamics method, we obtained insights on initial tribochemical reaction processes for the formation of tribofilm from the phosphoric ester molecule on the nascent Fe surface.     

Investigations of coupling characters in ionic liquids formed between the 1-ethyl-3-methylimidazolium cation and the glycine anion

In this study, novel ionic liquids formed between the 1-ethyl-3-methylimidazolium cation [emim]+ and the glycine anion [Gly]- have been investigated theoretically. The relevant geometrical characteristics, energy properties, the characters of the intermolecular hydrogen bonds (H bonds), and the possibility of proton transfer as well as IR characteristics have been systematically discussed. The natural bond orbital (NBO) and atoms in molecule (AIM) analyses have also been applied to understand the nature of the interactions between ionic pairs in ionic liquids. The most stable geometries have been determined by analyzing the relative energies and interaction energies, where the C-H...O intermolecular H bonds involving the protons attached to the imidazolium ring have been found to possess partial covalent character in nature. Electron transfers from the lone pairs of the carbonyl O atom of [Gly]- to the C-H antibonding orbital of the [emim]+ can explain the elongation and red shift of the C-H stretching frequency. The interaction modes are more favorable when the carbonyl O atoms of [Gly]- interact with the C2-H of the imidazolium ring and the C-H of the methyl group through the formation of double H bonds. The origin of the high stability of the amino acid ionic liquids observed experimentally may be attributed to the nonexistence of the proton-transferred products (neutral pairs) together with the large energy needed for separation of the ionic pairs. Additionally, the characteristics of the IR spectra have been analyzed to demonstrate the variants of the molecular structure of the [emim]+[Gly]- ionic liquids.     

带电组氨酸侧链与DNA碱基间非键作用强度的理论研究

采用MP2方法和6-31+G(d,p)基组优化得到了带有一个正电荷的组氨酸侧链与4个DNA碱基间形成的18个氢键复合物的气相稳定结构, 从文献中获取了组氨酸侧链与DNA碱基间形成的12个堆积和T型复合物的气相稳定结构, 使用包含基组重叠误差(BSSE)校正的MP2方法和aug-cc-pVTZ基组及密度泛函理论M06-2X-D3方法和aug-cc-pVDZ基组计算了这些复合物的结合能. 研究结果表明, 包含BSSE校正的M06-2X-D3方法和aug-cc-pVDZ基组能够给出较准确的结合能; 气相条件下, 组氨酸侧链与同种DNA碱基间的离子氢键作用明显强于堆积作用和T型作用, 组氨酸侧链最易通过离子氢键与胞嘧啶C和鸟嘌呤G作用形成氢键复合物, 组氨酸与胞嘧啶C和鸟嘌呤G间的T型作用强于与腺嘌呤A和胸腺嘧啶T间的离子氢键作用; 水相条件下, 组氨酸侧链与同种DNA碱基间的离子氢键作用仍明显强于堆积作用和T型作用, 组氨酸侧链更易与胞嘧啶C和鸟嘌呤G相互作用形成氢键复合物, 但是最强的组氨酸侧链与胞嘧啶C间的T型作用明显弱于与腺嘌呤A和胸腺嘧啶T间的离子氢键作用, 说明水相条件下组氨酸侧链与DNA碱基间主要通过离子氢键作用形成氢键复合物.     

聚丙烯微孔膜表面肝素化及其对低密度脂蛋白的吸附特性

为了赋予聚丙烯微孔膜(PPMM)选择性吸附低密度脂蛋白(LDL)的能力,发展了一种有效的PPMM表面共价固定肝素的方法.基于紫外引发丙烯酸的接枝聚合,通过碳二亚胺活化,以乙二胺为间隔臂,将肝素共价固定于PPMM表面,获得表面肝素化的PPMM.ATR-FTIR和XPS分析确证了修饰过程中膜表面基团及化学成分的变化.采用静...     

On inferences of bond character from bond length; the important role of nonbonded interactions

Although experimental molecular structure is one of the oldest and most frequently applied diagnostic tools in studies of the nature of chemical bonds, it is concluded that its application to all but the grossest details of bonds such as carbon-carbon bonds remains entirely speculative. The concept of bond length is discussed to emphasize the need for careful consideration of ambiguities associated with the natural indeterminacy of atomic positions. A theoretical basis is given to the empirical Schomaker-Stevenson rule relating bond length to electronegativity. The divergent views of Pauling and Walsh on hybridization, ionic character, and bond strength are reconciled to some extent with the aid of a simple model. It is shown that structural effects commonly attributed to conjugation, hyperconjugation, hybridization, and partial ionic character can be rationalized to a remarkable extent in terms of nonbonded interactions. It is suggested that these factors are not fundamentally as distinct from each other as they are often assumed to be, and that much more serious attention should be given to the role of nonbonded interactions.