二氧化硅负载聚-γ-(二苯胂基)丙基硅氧烷钯(0)配合物的合成与催化卤代芳烃的偶联反应

聚 γ 氯丙基硅氧烷依次与二苯胂钾、氯化钯作用 ,再经水合肼还原 ,合成了二氧化硅负载的聚 γ (二苯胂基 )丙基硅氧烷钯 (0 )配合物 .该钯 (0 )配合物可有效地催化芳基卤化物与烯烃、炔烃、Grignard试剂之间的交叉偶联反应 ,并且可以回收再用多次 ,其活性基本保持不变 .     

聚-γ-巯丙基硅氧烷羰基铑催化剂结构的XPS研究

<正> 本文报道聚-γ-巯丙基硅氧烷羰基铑催化剂结构上的研究结果。与以往作者报道的不同。这里的X-射线光电子能谱(XPS)实验结果证实这一新合成的催化剂是属于置换反应所导致的化合物型结构。同时定域在本文所研究的化合物分子中Rh离子和S离子上的Pauling计算电荷进一步支持作者的XPS试验结果。     

Conformation of Poly-L-methionine in Solution

A study of poly-L-methionine by viscosity, light-scattering, and NMR spectroscopy shows 1) that the helical rodhke form of the polypeptide has approximately the same dimensions as helical poly-γ-benzyl-L-glutamate, and 2) that the random coil form in trifluoroacetic acid is charged and fits the same Mark-Houwink equation as does poly-γ-benzyl-L-glutamate in dichloroacetic acid. The relationships between NMR Line widths and degree of polymerization is given for three different polypeptides.     

Pyrylium salts in the synthesis of redoxites

Redoxites poly(2,6-diphenyl-4-vinylpyran), poly(2,6-diphenyl-4-vinylpyrylium perchlorate), poly-(2,6-diphenyl-4-vinylpyridine) and poly(2,2′,6,6′-tetraphenyl-γ,γ′-dipyridine) were obtained based on pyrylium salts. Poly(2,2′,6,6′-tetraphenyl-γ,γ′-dipyridine) was transformed into the polyene to improve its film-forming and conducting properties. Electrochemical properties of polyviologen and conductive properties of the obtained polymers were studied.     

A large-scale synthesis of enantiomerically pure γ-hydroxy-organochalcogenides

Enantiomerically pure (R)- and (S)-γ-hydroxy-organochalcogenides are prepared using poly-[R]-3-hydroxybutanoate (PHB) as the starting material.     

Carbonyl allylation of aldehydes catalyzed by a silica-supported poly-γ-diphenylarsinopropylsiloxane palladium(0) complex

A silica-supported poly-γ-diphenylarsinopropylsiloxane palladium(0) complex has been prepared from γ-chloropropyltriethoxysilane via immobilization on fumed silica, followed by reacting with potassium diphenylarsenide and palladium chloride, and then the reduction with hydrazine hydrate. The palladium(0) complex has been found to catalyze the allylation of aldehydes via the formation of π-allylpalladium complexes, using allylic chlorides as allylating agent and SnCl₂ as reducing agent. This polymeric palladium complex can be recovered and reused.     

Effect of electrostatic field on the polymer chain in the quaternized reaction of polyvinylpyridine with alkyl halides

In order to discuss the electrostatic-field effect on a polymer reaction, the quaternization of poly-4-vinylpyridine–benzyl chloride (system I) was compared to that of poly-γ-chloromethylstyrene–γ-picoline (system II). In these two systems, the reaction initially proceeded according to the simple second-order kinetics. However, after the degree of quaternization exceeded 20–30 mole-%, a deviation from simple second-order kinetics occurred. In system I negative deviation occurred, while in system II positive deviation occurred. These phenomena occurred even though the solvent or the initial concentrations of the reactants were changed. The reasons for these phenomena are given below. In system I, the quaternized pyridine nitrogens prevented the benzyl chloride from approaching the unquaternized pyridine nitrogens. However, in system II the free γ-picoline was attracted by the quaternized chloro-γ-methyl site. Furthermore, the point at which the deviation occurred was determined by the degree of chloromethylation. All these results suggest that the effect of an electrostatic field must be presumed in these two systems.     

Deuterium NMR stereochemical analysis of threo–erythro isomers bearing remote stereogenic centres in racemic and non-racemic liquid crystalline solvents

We report the proton-decoupled deuterium NMR study of labelled diastereomers with remote stereogenic carbons dissolved in various mixtures of poly-γ-benzyl-l-glutamate (PBLG) and poly-γ-benzyl-d-glutamate (PBDG) liquid crystalline solutions. The evolution of quadrupolar splitting as well as the diastereomeric and the enantiomeric discrimination versus the proportion of PBLG and PBDG in the liquid crystalline phase is studied. It is shown that racemic liquid crystalline solutions of PBLG and PBDG may be used to measure diastereomeric excess (de). Thereafter the spectrum in PBLG solution allows for measuring the enantiomeric excess (ee) of each diastereomer. These first results suggest substantial prospects in the field of the analysis of diastereomers with remote stereogenic carbons.     

Novel method for preparation of cyclodextrin polymers: physico-chemical characterization and cytotoxicity

The objective of this work was to optimize the synthesis procedure of soluble cyclodextrin polymers developed by Weltrowski et al. The use of the parameters indicated by the latter in our laboratory led to a lower result, which did not exceed 15 % (w/w). The new method resulted simultaneously in two fractions, a water soluble one and an insoluble one with a yield of 40 and 85 % (w/w), respectively. Only soluble cyclodextrin polymers were characterized along with the cytotoxicity study. The optimized soluble polymers were characterized by Fourier-Transform Infrared Spectrophotometer, Thermogravimetric Analyzer, Differential Scanning Calorimetry, Powder X-Ray Diffraction Analysis and Size Exclusion Chromatography. In vitro cytotoxicity against peritoneal macrophage cells of female CD1 mice showed that soluble poly-α-CD and poly-γ-CD were less cytotoxic than soluble poly-β-CD at small dose and the opposite was true at higher dose. In conclusion, temperature and time could be used to optimize the yield of polymer cyclodextrins, which will have a broad use in the drug delivery system.     

Expression of ornithine decarboxylase during the transport of saquinavir across the blood-brain barrier using composite polymeric nanocarriers under an electromagnetic field

The expression of human ornithine decarboxylase (ODC) and permeability of saquinavir (SQV) across the blood-brain barrier were studied using nanoparticles (NPs) composed of poly(lactide-co-glycolide) (PLGA), poly-(γ-glutamic acid) (γ-PGA), and polyethyleneimine (PEI). SQV was encapsulated in the particle core to traverse a monolayer of human brain-microvascular endothelial cells (HBMECs) with the regulation of human astrocytes under an electromagnetic field (EMF). An increase in the weight percentage of PEI enhanced the particle size, zeta potential, and permeability of SQV. However, the viability of HBMECs reduced when the weight percentage of PEI increased. In addition, an increment in the molecular weight of γ-PGA enhanced the particle size and viability of HBMECs, and reduced the zeta potential. The permeability of SQV and expression of ODC were in the order: an EMF with amplitude modulation (AM)>an EMF with frequency modulation>no EMF. At 0.04% PEI, the AM EMF increased 2.38 times the uptake of NPs and 2.72 times the expression of ODC. The combination of PEI/γ-PGA/PLGA NPs and EMF can be an innovative strategy for delivering SQV into the brain.     

含氨基酸侧链的有机硅高分子催化剂——Ⅸ.聚γ-(甘-色二肽基)丙基硅氧烷钯催化剂的合成、加氢活性及结构表征

本文报道了不同N/Pd摩尔比的聚γ-(甘-色二肽基)丙基硅氧烷钯催化剂的合成及对烯烃和硝基苯的加氢活性.催化剂的结构表征说明,其活性中心的组成可能是氨基酸配体的羧基与PdCl_2的络合.这种催化剂对丙烯腈和苯乙烯有较高的加氢活性,而对硝基苯的氢化没有催化活性.并研究了溶剂和温度对加氢活性的影响.     

5-氟尿嘧啶-聚[N-(2-羟乙基)-L-谷酰胺]的合成及缓释性能研究

以聚谷氨酸苄酯为原料,用乙醇胺进行胺解得水溶性的可生物降解的聚[N-(2-羟乙基)-L-谷酰胺];用光气/甲苯液活化5-氟尿嘧啶,将其以共价键形式键合在高分子上,得5-氟尿嘧啶的高分子前药。用IR、UV、1HNMR及DSC对其结构进行表征,用紫外光谱测定其药物含量,载药高分子的接药率约为38.4%,高分子前药在pH=7.2的磷酸盐介质中42天内的药物累积释放量为57.53%。实验结果表明,5-氟尿嘧啶以共价键的形式键合在聚[N-(2-羟乙基)-L-谷酰胺]之上,在体外有明显的缓释效果。     

高分子钯络合物催化的亚胺化合物的加氢反应

制备了一系列以二氧化硅为载体的侧链上含有各种氮配位基团的聚硅氧烷-钯络合物,这些高分子钯络合物能够在常温常压下催化亚胺化合物的加氢反应并表现出不同程度的催化活性.对其中聚-(N,N-二乙酰基)-γ-氨丙基硅氧烷-钯络合物催化的亚苄基苯胺的加氢反应做了比较深入的研究,发现该催化剂在反应中是稳定的并给出唯一的加氢产物,络合物中的N/Pd原子比、反应温度以及不同底物对反应速度的影响也被报道.     

Polyethyleneimine/poly-(γ-glutamic acid)/poly(lactide-co-glycolide) nanoparticles for loading and releasing antiretroviral drug

Nanoparticles (NPs) with ternary components of polyethyleneimine (PEI), poly-(γ-glutamic acid) (γ-PGA), and poly(lactide-co-glycolide) (PLGA) were applied to carry and release saquinavir (SQV). Hydrophobic SQV was encapsulated in the particle core composed of PLGA to form SQV-PLGA NPs, and the surface of SQV-PLGA NPs was grafted successively with hydrophilic γ-PGA and PEI (PEI/γ-PGA/SQV-PLGA NPs). The morphological images revealed that PEI/γ-PGA/SQV-PLGA NPs were spheroid-like, in general. An increase in the concentration of didecyl dimethylammonium bromide and a reduction in the dose of SQV enhanced the entrapment efficiency of SQV in PLGA NPs. In addition, an increment in the molecular weight of γ-PGA reduced the grafting efficiency of PEI on γ-PGA/SQV-PLGA NPs. An increase in the weight percentage of PEI enhanced the average particle diameter. However, the grafting efficiency of PEI on γ-PGA/SQV-PLGA NPs and the dissolution rate of SQV from PEI/γ-PGA/SQV-PLGA NPs reduced when the weight percentage of PEI increased. PEI/γ-PGA/SQV-PLGA NPs are an innovative drug delivery system and can be used for antiretroviral trials.     

Synthesis and magnetic properties of the γ-Fe2O3/poly-(methyl methacrylate)-core/shell nanoparticles

The synthesis of γ-Fe₂O₃/poly-(methyl methacrylate)-core/shell nanoparticles and their magnetic properties are reported. Specific γ-Fe₂O₃ nanoparticles capable of initiating atom transfer radical polymerization (ATRP) were prepared by a ligand exchange reaction of ((chloromethyl)phenylethyl)-dimethylchlorosilane and caprylate-capped γ-Fe₂O₃ nanoparticles of 4 nm in diameter, and the ATRP of methyl methacrylate was carried out subsequently. These nanoparticles were characterized with Fourier transform infrared spectroscopy, transmission electron microscopy and Mössbauer spectroscopy. Low temperature magnetic properties investigated with SQUID magnetometry revealed that the coercivity and the blocking temperature changed slightly owing to surface effects.     

Thermal stabilities of homopolymers of amino acids

In order to study the thermal stabilities of the α-helical polyamino acids in the solid state, measurements of the infrared spectra at high temperature, weight loss by thermogravimetry, and the expansion of the α-helix by x-ray diffractometry were carried out on poly(γ-methyl D -glutamate), poly(γ-benzyl L -glutamate), poly-L -alanine, poly(β-benzyl L -aspartate), poly-δ-carbobenzoxy-L -ornithine and poly-ε-carbobenzoxy-L -lysine. The thermal degradation temperatures of these polymers lie between 140°C and 230°C. The α-helical conformation is stable at high temperature in these polyamino acids, except for poly(β-benzyl L -asparatate), unless thermal degradation takes place. As temperature rises, the amide A and the amide I bands of the infrared spectra shift slightly to higher frequencies and the amide II band to lower frequencies. At the same time, the intensities of these amide bands decrease. These changes differ among the different molecules. From the x-ray measurement, it was found that the α-helix expands along the helical axis with temperature. It is expected that the intramolecular hydrogen bonds of the α-helix become weak with increasing temperature and that the state of the hydrogen bonds of the α-helices depends upon the molecules.     

聚γ-(m-二苯膦苯基)丙基硅氧烷——铂络合物对烯烃硅氢化反应的催化特征

本文报道二氧化硅负载的三苯膦铂络合物——聚γ-(m-二苯膦苯基)丙基硅氧烷铂络合物对三甲氧基硅烷与不饱和化合物进行硅氢加成反应的催化特性.在底物用量的万分之一摩尔量的铂络合物存在下,1-己烯、1-癸烯、1-十二碳烯、苯基烯丙醚和ω-氯代十一碳烯在60或40℃平稳地与三甲氧基硅烷发生硅氢加成反应,唯一地得到末端加成产物,产率均在85％以上.其催化活性在反应初期低于四(三苯膦)合铂,但后期反应速度和硅氢化产率均较高.实验表明,聚γ-(m-二苯膦苯基)丙基硅氧烷与四(三苯膦)合铂反应制得的铂络合物(1)比与氯铂酸反应制得的铂络合物(Ⅱ)催化活性高.其次,反应气氛对硅氢加成反应具有决定性的影响.在空气气氛中,硅氢化反应平稳地进行;在氮气气氛中,不发生反应.     

Enantiomeric recognition of chiral invertomers through NMR in chiral oriented phases: a study of cis-decalin

We describe a deuterium 1D and 2D NMR study of cis-decalin in various chiral and achiral polypeptide oriented solvent systems and the effect of the acquisition temperature. Organic solutions of poly-γ-benzyl-l-glutamate (PBLG) or poly-ε-carbobenzyloxy-l-lysine (PCBLL) in dichloromethane or chloroform allow the chiral invertomers of cis-decalin to be differentiated at low temperature. At high temperature, it is possible to distinguish between deuterium nuclei of the molecule which become enantiotopic under rapid kinetic averaging. The results obtained illustrate the capability of such polypeptide liquid-crystalline solvents to enantioselectively interact with unfunctionalised chiral cycloalkanes and highlight the analytical potential of NMR analysis in chiral liquid crystal based solvents in the investigation of interconverting chiral conformers.     

Self-Healing Supramolecular Materials Constructed by Copolymerization via Molecular Recognition of Cavitand-Based Coordination Capsules

The repeating guest units of poly-(R)- 2 were selectively encapsulated by the self-assembled capsule poly- 1 possessing eight polymer side chains to form the supramolecular graft polymer (poly- 1 )_n⋅poly-(R)- 2 . The encapsulation of the guest units was confirmed by ¹H NMR spectroscopy and the DOSY technique. The hydrodynamic radius of the graft polymer structure was greatly increased upon the complexation of poly- 1 . The supramolecular graft polymer (poly- 1 )_n⋅poly-(R)- 2 was stably formed in the 1:1 host–guest ratio, which increased the glass transition temperature by more than 10 °C compared to that of poly- 1 . AFM visualized that (poly- 1 )_n⋅poly-(R)- 2 formed the networked structure on mica. The (poly- 1 )_n⋅poly-(R)- 2 gelled in 1,1,2,2-tetrachloroethane, which led to fabrication of distinct viscoelastic materials that demonstrated self-healing behavior in a tensile test.