以四肽自组装体为模板制备手性3-氨基苯酚甲醛树脂纳米纤维

采用经典的固相合成法制备了一对烷基取代丙氨酸四肽衍生物对映体,研究了其在不同溶剂中的成胶行为,并以其在甲醇中形成的超分子自组装体为模板,利用溶胶-凝胶法制备了单手螺旋3-氨基苯酚甲醛树脂纳米纤维.利用扫描电子显微镜和透射电子显微镜观察超分子自组装体及3-氨基苯酚甲醛树脂的螺旋形貌,并利用圆二色谱研究其光学性质.研究发现,3-氨基苯酚甲醛树脂纳米纤维既具有纳米尺度的手性,又具有分子尺度的手性.手性从小分子形成的自组装体传递到高分子树脂中.     

二苯丙氨酸短肽手性结构的可控组装

以阳离子二苯丙氨酸（Cationic dipeptide,CDP）为组装基元,通过控制熟化时间,在乙醇溶液中分别获得了平滑的纳米纤维和螺旋纤维结构.通过红外光谱和圆二色光谱系统研究了CDP在乙醇溶液中的组装体随时间的变化.研究发现,CDP在乙醇中可以组装成纳米纤维的结构.随着在乙醇中熟化时间的增加,CDP纳米纤维发生扭曲,最终组装成绳状的螺旋纤维结构.光谱数据分析表明纳米纤维转变成螺旋纤维主要源于相邻肽分子中的正电荷之间的强静电排斥作用和肽分子间氢键作用控制的β-折叠二级结构.这项工作通过简单的控制熟化时间实现了对超分子组装体结构的调控,为超分子手性组装体的可控制备提供了一种简单可行的方法.     

分子链构象变化对高分子液晶相行为的影响

聚肽高分子溶解在含有机酸的有机溶剂中可以在室温条件下形成液晶．随着温度的下降,体系中的酸分子会引起聚肽分子链发生由刚性螺旋结构向柔性无规线团结构的构象转变．这种转变将导致一个由液晶态向非液晶态的相变．在Ｆｌｏｒｙ格子理论和Ｚｉｍｍ Ｂｒａｇｇ理论的基础上,作者已提出了有关这一现象的理论解释,并通过引入一个与温度有关的库恩链长径比ｘｋ,使理论进一步完善,更切实际地解释聚肽液晶的相行为．此外,还讨论了不同分子刚柔性,不同高分子 溶剂作用系数χ对液晶相行为的影响,以及研究了聚肽液晶的有序参数．     

电场对聚肽液晶相行为的影响

聚合物液晶的相转变不仅可以通过溶液温度或聚合物的浓度的改变来实现,也可以通过施加外电场、磁场等取向场来达到．在二氧六环、氯仿、间甲酚等支持聚肽a一螺旋构象的溶剂中,当PBLG(聚L-谷氨酸γ-苯甲酯)达到一定的浓度会形成胆甾型溶致液晶．对这种液晶施加强度足够     

聚赖氨酸为主链的牙刷状分子刷的可控合成

设计合成了溴基功能化的赖氨酸单体(Br-lys)并通过关环反应制备了对应的溴代L-赖氨酸N-羧酸酐(Br-Lys-NCA)单体.利用过渡金属引发剂Ni(COD)depe调控的NCA活性开环聚合和顺序添加单体的方法,得到了组成和结构明确的聚(ε苄氧羰基L-赖氨酸)-b-PBrLL(PZLL-PBrLL)两嵌段共聚肽.利用PZLL-b-PBrLL两嵌段共聚肽为大分子引发剂,通过ATRP引发甲基丙烯酸寡聚乙二醇酯(EGMA),合成了以聚赖氨酸为骨架的牙刷状分子刷.研究发现PZLL-PBrLL两嵌段在四氢呋喃中形成α-螺旋结构,螺旋度随着PBrLL链段的增长而降低,而PZLL-b-(PBrLL-g-PEGMA)形成部分α-螺旋构象,螺旋度随侧链PEGMA增长而减小.     

聚苯乙烯-b-聚谷氨酸苄酯刚柔嵌段共聚物的合成及其层状形貌考察

以末端带胺基的聚苯乙烯(PS-NH2)为引发剂,利用N-羧酸内酸酐(N-carbonyl anhydride,NCA)法制备一种刚柔二嵌段共聚物聚苯乙烯-b-聚(γ-苄基-L-谷氨酸酯)(polystyrene-b-poly(γ-benzyl-L-glutamate),PS-b-PBLG)杂化聚肽,并研究该聚肽嵌段共聚物的分子结构、热性能、液晶性与自组装形貌的溶剂效应.以氢核磁共振波谱(1H-NMR)和凝胶渗透色谱仪(GPC)表征两嵌段的摩尔比、分子量及其分布.利用示差扫描量热分析仪(DSC)与光学显微镜(POM)考察材料的热性质与液晶性.由小角X射线散射(SAXS)分析得知,两嵌段组分呈交替分布层状结构,聚肽层中α螺旋链在不同溶剂中会发生不同程度折叠;通过透射扫描电镜(TEM)清楚观察到PS-b-PBLG在1,2-二氯乙烷(EDC)中α螺旋折叠形成了条纹式层状形貌,不同于1,1,2,2-四氯乙烷(TCE)中α螺旋完全伸展形成的锯齿式层状形貌.     

单分散的还原态和中间氧化态聚苯胺齐聚物的合成与紫外光谱研究

提出了一条合成苯胺齐聚物的新路线:由高氧化态的苯胺四聚体与二苯胺或N-苯基-1,4-对苯二胺反应合成苯基封端的苯胺五聚体和六聚体,用红外、质谱、核磁共振、基底辅助激光解吸质谱(MALDI-MS)进行了表征.提出一条可能的机理,即高氧化态的苯胺四聚体与二苯胺或N-苯基-1,4-对苯二胺在酸性溶液中混合时,四聚体、二苯胺和N-苯基-1,4-对苯二胺的分子中均形成阳离子自由基,四聚体的阳离子自由基与后二者的阳离子自由基耦合形成苯胺五聚体和六聚体.还原态的苯胺齐聚物氧化成中间氧化态的苯胺齐聚物,使用硫酸铵和六水和三氯化铁等氧化剂能打断苯胺五聚体和六聚体的分子链.实验发现,氧化银是将还原态苯胺齐聚物氧化成中间氧化态的齐聚物的最好的氧化剂.用紫外可见光谱对中间氧化态的五聚体和六聚体进行了研究,对其分子中醌环的数目进行了讨论.     

点击反应在糖聚肽及其类似物合成中的应用

糖聚肽是一类由聚肽/聚氨基酸与糖类化合物共价相连构成的高分子化合物,因其良好的生物相容性及独特的生物学性能,在自组装、组织工程、药物输送等领域均显示出广泛的应用前景,成为近年来蓬勃发展的热点领域.高效合成结构规整可控的糖聚肽是该领域的热点和难点.点击化学的快速发展为糖聚肽的合成提供了高效便捷的途径.系统综述了点击反应在糖聚肽两种合成策略中的应用——通过聚合后修饰法将糖分子引入到聚氨基酸前体侧链上以及对糖苷化的α-氨基酸-N-羧酸酐(glyco-NCA)"可点击"化学单体的开环聚合反应,同时也总结了通过点击反应将含糖功能基元化学偶联到聚氨基酸链末端合成糖聚肽类似物的策略,并对其优缺点和发展方向进行了简要讨论.     

聚肽螺旋纳米弯棒的制备与形成机理

通过五元环酸酐（NCA）开环聚合的方法成功合成了聚(γ-苄基-L-谷氨酸酯)（PBLG）聚肽均聚物和聚(γ-苄基-L-谷氨酸酯)-b-聚乙二醇（PBLG-b-PEG）聚肽嵌段共聚物，并通过酸解脱苄基及与肉桂醇的酯化反应对PBLG-b-PEG嵌段共聚物改性，制备了聚(γ-苄基-L-谷氨酸酯-co-肉桂基-L-谷氨酸酯)-b-聚乙二醇（P(BLG/CLG)-b-PEG）改性嵌段共聚物，其聚肽侧链上修饰了可光交联的肉桂酰氧基，其C=C双键在紫外光照射下能发生环加成反应交联聚肽链段。采用四氢呋喃-N,N-二甲基甲酰胺（THF-DMF）有机共溶剂溶解、选择性溶剂（水）沉淀的自组装方法制备了PBLG纳米棒；然后向纳米棒水溶液中加入THF溶剂诱导纳米棒弯曲，制备了纳米弯棒。通过THF的加入量可以调控纳米棒的弯曲程度。利用类似的方法，通过PBLG与PBLG-b-PEG或P(BLG/CLG)-b-PEG共组装制备了螺旋纳米棒（其中PBLG均聚物形成棒状内核、PBLG-b-PEG或P(BLG/CLG)-b-PEG形成表面纳米螺纹），然后向螺旋纳米棒水溶液中加入THF溶剂，但是仅得到了光滑纳米弯棒（表面螺纹...     

基于药效团的血管紧张素转换酶抑制肽的结构优化

采用Discovery Studio2．0中的药效团模型生成方法,产生了基于化学特征的ACE抑制肽的药效团模型．所选择的认为最好的药效团模型（Hypo1）含有5个化学特征（1个阴离子中心、1个氢键受体、1个氢键给体、2个疏水中心）．我们先前采用实验的方法,从蚕蛹蛋白中获得具有ACE抑制活性的六肽分子,本文结合产生的ACE抑制肽药效团模型和分子对接研究,对该六肽分子进行结构优化,以识别六肽中对ACE抑制活性起关键作用的结构部分．结果显示,药效团模型的方法可有效用于ACE抑制肽的结构优化．     

Intramolecular metathesis of a vinyl group with vinylidene C=C double bond in Ru complexes

The cationic complex {[Ru]=C=CHCPh2CH2CH=CH2}BF4 (3a, [Ru] = (eta5-C5H5)(PPh3)2Ru) in solution transforms to {[Ru]=C=CHCH2CPh2CH=CH2}BF4 (4a) via a new metathesis process of the terminal vinyl group with the C=C of the vinylidene group which is confirmed by 13C labeling studies. This transformation is irreversible as revealed by deuteration and decomplexation studies. The cationic complex {[Ru]=C=CHCPh2CH2CMe=CH2}BF4 (3b) undergoes a cyclization process yielding 6b containing a eta2-cyclic allene ligand which is fully characterized by single-crystal X-ray diffraction analysis. Analogous complexes 4a' and 6b' ([Ru] = (eta5-C5H5)(dppe)Ru) containing dppe ligands were similarly obtained from protonation of the corresponding acetylide complexes via formation of vinylidene intermediate. Protonation of the acetylide complex containing a terminal alkynyl group [Ru]-CCCPh2CH2CCH (2c) generates the vinylidene complex {[Ru]=C=CHCPh2CH2CCH}BF4 (3c) which again undergoes an irreversible transformation to give {[Ru]=C=CHCH2CPh2CCH}BF4 (4c) possibly via a pi-coordinated alkynyl complex followed by hydrogen and metal migration. No similar transformation is observed for the analogous dppe complex 3c'. With an extra methylene group, complex {[Ru]=C=CHCPh2CH2CH2CH=CH2}BF4 (3d) and complex {[Ru]=C=CHCPh2CH2Ph}BF4 (3e) are stable. The presence of a gem-diphenylmethylene moiety at the vinylidene ligand with the appropriate terminal vinyl or alkynyl group along with the correct steric environment implements such a novel reactivity in the ruthenium vinylidene complexes.     

Non-heme iron(II) complexes containing tripodal tetradentate nitrogen ligands and their application in alkane oxidation catalysis

A series of iron(II) bis(triflate) complexes containing tripodal tetradentate nitrogen ligands with pyridine and dimethylamine donors of the type [N(CH(2)Pyr)(3-n)()(CH(2)CH(2)NMe(2))(n)] [n = 0 (tpa, 1), n = 1 (iso-bpmen, 3), n = 2 (Me(4)-benpa, 4), n = 3 (Me(6)-tren, 5)] and the linear tetradentate ligand [(CH(2)Pyr)MeN(CH(2)CH(2))NMe(CH(2)Pyr), (bpmen, 2)] has been prepared. The preferred coordination geometry of these complexes in the solid state and in CH(2)Cl(2) solution changes from six- to five-coordinate in the order from 1 to 5. In acetonitrile, the triflate ligands of all complexes are readily displaced by acetonitrile ligands. The complex [Fe(1)(CH(3)CN)(2)](2+) is essentially low spin at room temperature, whereas ligands with fewer pyridine donors increase the preference for high-spin Fe(II). Both the number of pyridine donors and the spin state of the metal center strongly affect the intensity of a characteristic MLCT band around 400 nm. The catalytic properties of the complexes for the oxidation of alkanes have been evaluated, using cyclohexane as the substrate. Complexes containing ligands 1-3 are more active and selective catalysts, possibly operating via a metal-based oxidation mechanism, whereas complexes containing ligands 4 and 5 give rise to Fenton-type chemistry.     

Characterisation of four new two-dimensional lithium beryllofluoro-layered compounds

Four new amine-templated materials, containing two-dimensional lithium beryllofluoride sheets of the stoichiometry [LiBeF(4)](-), have been synthesised under hydrothermal and ambient pressure conditions. [LiBeF(4)][C(6)H(4)(CH(3))CH(2)NH(3)] (1), [LiBeF(4)][C(6)H(4)CH(2)NH(3)Cl] (2), [LiBeF(4)](2)[NH(3)CH(2)CH(2)CH(2)NH(3)] (3), and [LiBeF(4)][C(6)H(5)CH(2)CH(2)CH(2)NH(3)] (4) all contain well-separated anionic sheets containing two different topologies with the 'inter-layer' regions comprising of organoamine templating species. Use of the different organoamine templating agents results in compounds possessing very different relative arrangements of the lithium beryllofluoride sheets. The materials crystallise in P-centred orthorhombic and monoclinic cells; for 1 (templating agent: 3-methylbenzylamine) Pca2(1); for 2 (4-chlorobenzylamine) Pbca; for 3 (1,3-diamminopropane) Pccn, and for 4 (3-phenyl-1-propylamine) P2(1)/c. Hydrogen bonding exists between ions situated on the protonated amine groups on the templating species and electronegative fluoride ions, on MF(4) tetrahedra (where M=Li and Be).     

A novel cationic heteropolyoxovanadium(IV) cluster functionalized with organic ligands: synthesis and characterization of the fully reduced species [Mn(II)V(IV)6O6[(OCH2CH2)2N(CH2CH2OH)]6]Cl2

The solvothermal reaction of (HOCH2CH2)3N with [(n-C4H9)4N]3[H3V10O28] and MnCl2 x 4H2O in CH3CN and CH3OH yields a novel cationic heteropolyoxovanadium(IV) cluster, [Mn(II)V(IV)6O6[(OCH2CH2)2N(CH2CH2OH)]6]2+, containing a fully reduced new cyclic [MnV6N6O18] core with the Anderson structure.     

Electrodeposition of germanium from supercritical fluids

Several Ge(II) and Ge(IV) compounds were investigated as possible reagents for the electrodeposition of Ge from liquid CH(3)CN and CH(2)F(2) and supercritical CO(2) containing as a co-solvent CH(3)CN (scCO(2)) and supercritical CH(2)F(2) (scCH(2)F(2)). For Ge(II) reagents the most promising results were obtained using [NBu(n)(4)][GeCl(3)]. However the reproducibility was poor and the reduction currents were significantly less than the estimated mass transport limited values. Deposition of Ge containing films was possible at high cathodic potential from [NBu(n)(4)][GeCl(3)] in liquid CH(3)CN and supercritical CO(2) containing CH(3)CN but in all cases they were heavily contaminated by C, O, F and Cl. Much more promising results were obtained using GeCl(4) in liquid CH(2)F(2) and supercritical CH(2)F(2). In this case the reduction currents were consistent with mass transport limited reduction and bulk electrodeposition produced amorphous films of Ge. Characterisation by XPS showed the presence of low levels of O, F and C, XPS confirmed the presence of Ge together with germanium oxides, and Raman spectroscopy showed that the as deposited amorphous Ge could be crystallised by the laser used in obtaining the Raman measurements.     

Anodization in oligo(ethylene glycol) as an initial derivatization tool for preparing glassy carbon electrodes covalently modified with amino compounds: effective access to a 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-modified glassy carbon electrode

Anodization in HO(CH2CH2O)nH (1a, n=2; 1b, n=3; 1c, n=4) as an initial derivatization tool for preparing glassy carbon (GC) electrodes covalently modified with amino compounds was explored. As an amino compound to be immobilized, 4-amino-2,2,6,6-tetramethylpiperidinyl-1-oxyl (4-amino-TEMPO) was selected. When GC electrodes anodized at 2.0 V vs. Ag wire coated with AgCl in 1 containing RCH2CH2SO3Na (2a, R=H; 2b, R=OH) were treated with a N,N-dimethylformamide (DMF) or CH2Cl2 solution of 4-amino-TEMPO and 1,3-dicyclohexylcarbodiimide (DCC), TEMPO-modified GC electrodes were afforded. Coverage (gammaTEMPO) of the electrode surfaces by TEMPO was estimated by cyclic voltammetry in CH3CN containing NaClO4. A TEMPO-modified GC electrode with the best gammaTEMPO (1.36 x 10(-10) mol/cm2) was obtained by anodization in 1b containing 2a at the expense of 3.0 C followed by amidization in DMF for 7 d. On cyclic voltammetry, the TEMPO-modified GC electrode showed good and stable electrocatalytic ability for oxidation of allyl alcohol in the presence of 2,6-lutidine.     

Synthesis and characterization of six-coordinate "3 + 2" mixed-ligand oxorhenium complexes with the o-diphenylphosphinophenolato ligand and tridentate coligands of different N and S donor atom combinations

A series of octahedral six-coordinate oxorhenium(V) mixed ligand complexes containing the common [ReO(L)]2+ fragment (L = o-OC6H4P(C6H5)2] have been synthesized and characterized. Hence, it was shown that the [ReO(L)]2+ moiety can accommodate a variety of tridentate ligands containing a central amine group amenable to deprotonation and different combinations of lateral groups, such as ethylamine, substituted ethylamine, ethylthiol, and ethylthioether arms. In particular, by reaction of equimolar amounts of the pertinent HLn ligands with the [(n-C4H9)4N][ReOCl3(L)] precursor in refluxing acetonitrile/methanol or dichloromethane/methanol mixtures, the following series of [ReO(Ln)(L)]+/0 oxorhenium(V) complexes has been generated: ReO[[N(CH2CH2NH2)2][o-OC6H4P(C6H5)2]]Cl (1); ReO[[C2H5)2NCH2CH2NCH2CH2S][o-OC6H4P5)2]] (2); ReO[[(CH2)4NCH2CH2NCH2CH2S][o-OC6H4P(C6H4P(C6H5)2]] (3); and ReO[[C2H5SCH2CH2NCH2CH2S][o-OC6H4P(C6H5)2]] (4). The complexes are closed-shell 18-electron oxorhenium species, which adopt octahedral geometries both in solution and in the solid state, as established by conventional physicochemical techniques including multinuclear NMR and single-crystal X-ray diffraction analyses.     

某些含二茂铁基的酰氧基茂锆配合物的合成

本文由二氯二茂锆和二氯二(甲基环戊二烯基)锆与二茂铁羧酸钠盐反应合成了六种二茂铁酰氧基茂锆配合物,R_2ZrClY:R=C_5H_5,Y=FcCOO(1),FcCH_2COO(2),FcCOCH_2CH_2COO(3);R=CH_3C_5H_4,Y=FcCOO(4),FcCH_2C0O(5),FcCOCH_2CH_2COO(6)(Fc=二茂铁基)。     

Li(thf)3cyclo-(P4tBu4CH)]--synthesis, molecular structure and dynamic behaviour

[Li(thf)3cyclo-(P4tBu4CH)] (2-Li), containing the first tetraphosphacyclopentanide anion cyclo-(P4tBu4CH)- (2), was prepared, and its dynamic behaviour in solution analysed by variable-temperature 31P NMR spectroscopy.     

Photodissociation of S atom containing amino acid chromophores

Photodissociation of 3-(methylthio)propylamine and cysteamine, the chromophores of S atom containing amino acid methionine and cysteine, respectively, was studied separately in a molecular beam at 193 nm using multimass ion imaging techniques. Four dissociation channels were observed for 3-(methylthio)propylamine, including (1) CH(3)SCH(2)CH(2)CH(2)NH(2)-->CH(3)SCH(2)CH(2)CH(2)NH+H, (2) CH(3)SCH(2)CH(2)CH(2)NH(2)-->CH(3)+SCH(2)CH(2)CH(2)NH(2), (3) CH(3)SCH(2)CH(2)CH(2)NH(2)-->CH(3)S+CH(2)CH(2)CH(2)NH(2), and (4) CH(3)SCH(2)CH(2)CH(2)NH(2)-->CH(3)SCH(2)+CH(2)CH(2)NH(2). Two dissociation channels were observed from cysteamine, including (5) HSCH(2)CH(2)NH(2)-->HS+CH(2)CH(2)NH(2) and (6) HSCH(2)CH(2)NH(2)-->HSCH(2)+CH(2)NH(2). The photofragment translational energy distributions suggest that reaction (1) and parts of the reactions (2), (3), (5) occur on the repulsive excited states. However, reaction (4), (6) occur only after the internal conversion to the electronic ground state. Since the dissociation from an excited state with a repulsive potential energy surface is very fast, it would not be quenched completely even in the condensed phase. Our results indicate that reactions following dissociation may play an important role in the UV photochemistry of S atom containing amino acid chromophores in the condensed phase. A comparison with the potential energy surface from ab initio calculations and branching ratios from RRKM calculations was made.