Synthesis and Kinetic Study on the Chromium(III) Complex [Cr(ASA)(en)2]Cl·2H2O

In order to explore the transfer mechanism of chromium(III) in mammals, a novel complex [Cr(ASA)(en)₂]Cl· 2H₂O, bis(ethylenediamine‐ κ ² N,N′)(4‐aminosalicylic acid‐ κ ² O,O′) chromium(III) monochloride dihydrate was synthesized (4‐aminosalicylic acid=H₂ASA, ethylenediamine=en). The crystal structure belongs to orthorhombic system with the space group P2₁2₁2₁ by means of X‐ray diffraction. The characteristic for transfer of Cr³⁺ from the compound to the low‐molecular‐mass chelator EDTA and the iron‐binding protein apoovotransferrin (apoOTf) was followed by UV‐visible (UV‐Vis) and fluorescence spectra in 0.01 mol·L^?1 Hepes at pH 7.4. The second order rate constants were calculated. Those spectra in conjunction were used to obtain more accurate information about the interaction of chromium complex with apoOTf. The experimental results indicate that Cr³⁺ can be transferred from the complex to apoOTf with the retention of the 4‐aminosalicylic acid acting as a synergistic anion.     

On the nature of atomic shell approximation (ASA) electrostatic molecular potentials (EMP)

General properties of the electrostatic molecular potential (EMP) when obtained by means of the atomic shell approximation (ASA) density function (DF) are discussed. In the present study it is proved that in general and without exceptions promolecular ASA DF provide EMP which are everywhere repulsive. The polarized ASA DF version, providing an alternative enhanced kind of EMP, behaves in such a way that in the neighborhood of negative charged atoms, attractive regions appear resembling the ab initio results.     

1,3-PBO扩链改性端羧基聚乳酸的性能表征

以乳酸为原料、辛酸亚锡为催化剂,采用梯度升温法,在170℃、0.098 MPa条件下直接熔融缩聚合成端羧基共聚物P(LA/SA).将其用2,2-(1,3-亚苯基)-二噁唑啉(1,3-PBO)扩链,按n(—COOH)/n(—oxazoline)=1∶1.4比例加入1,3-PBO,在150℃,0.098 MPa条件下反应15 min制得聚酰胺酯(PEA).采用GPC、FTIR、1H-NMR、DSC、XRD、TGA、SEM等手段对聚合物的结构进行了表征和性能测试.结果表明,与P(LA/SA)相比,扩链产物相对分子质量大幅度提高,重均分子量达36×104;产物Tg比PLA升高,材料的刚性增强;产物热稳定性能提高,为一步分解;产物结晶度较P(LA/SA)降低,其柔韧性较P(LA/SA)增强,但相对于PLA有所降低.     

Preparation of ASA (acrylonitrile-styrene-acrylate) structural latexes via seeded emulsion polymerization

Acrylonitrile-styrene-acrylate (ASA) structural latexes were synthesized in a two-stage seeded emulsion polymerization. In the first-stage, partially cross-linked poly (n-butyl acrylate) (PnBA) and poly (n-butyl acrylate-stat-2-ethyl hexyl acrylate) P (nBA-stat-2EHA) (75/25 by wt) rubber cores were synthesized, and then in the second-stage, a hard poly (styrene-stat-acrylonitrile) (SAN) (70/30 by wt) shell was grafted on to the rubber seeds. The effects of surfactant type and second-stage monomer addition mode have been investigated on the final morphology of two-stage emulsion particles. The results indicated that an application of anionic surfactant, that is, sodium dodecyl sulfonate (SDS), along with sodium persulfate (KPS) initiator for both stages, and with first-stage tert-butyl hydroperoxide (t-BHP) and second-stage KPS initiators led to a hemisphere particle morphology. On the other hand, raspberry and core-shell structures were observed for the structural latexes, which were prepared using a non-ionic surfactant, that is, nonylphenol ethoxylated polyethylene glycol (Igepal CO-850), accompanying KPS initiator for both stages. It is clear, however, that the relative surface hydrophilicity of the core phase, altered by the surfactant type considerably affected the type of morphology formed. For obtained structural latexes, the gradual addition of the second-stage monomers to the core latexes resulted in a fairly real core-shell structure with a higher shell thickness. On the contrary, a raspberry structure in which the rubber phase was enlarged by the second-stage polymer microdomains was observed for the second-stage monomer addition batch. In fact, the shell semi-batch polymerization conditions lower the shell plasticizing effect, and increase the kinetic barrier to prevent from further second-stage monomer diffusion and microdomain formation within the rubbery phase.     

Preparation and characterization of asymmetric polyethersulfone (PES) membranes

Flat‐sheet asymmetric polyethersulfone (PES) membranes were prepared from polyethersulfone (PES)/ polyethylene glycol (PEG)/ N‐methyl‐2‐pyrrolidone (NMP) system via phase inversion induced by immersion precipitation in water coagulation bath. Effects of propionic acid (PA) as a non‐solvent additive (NSA) on morphology and performance of the membranes prepared from PES/PEG 6000/NMP system in water coagulation bath were investigated. The cross section morphology of the membranes was studied by scanning electron microscopy (SEM). In addition, performance of the membranes was studied by water content measurements and separation experiments using pure water and human serum albumin (HSA) protein solution as feeds. According to SEM analysis, it was found out that the NSA has a significant influence on the structure of the skin layer and the sublayer. The obtained results indicated that addition of PA to the casting solution decreases permeation flux of the prepared membranes. Copyright © 2009 John Wiley & Sons, Ltd.     

Phase state diagrams of the poly(dimethylsiloxane)—poly(diethylsiloxane) system

Phase equilibria in the poly(dimethylsiloxane)(PDMS)—polydiethylsiloxane (PDES) system in the amorphous and liquid-crystal states were studied by optical interferometry. The findings obtained were compared with the data of calorimetric measurements. The experiments were carried out in a wide range of molecular weights and temperatures, and the phase diagrams were constructed. Thermodynamic analysis of the experimental data was performed in the framework of the Flory—Haggins theory for polymeric solutions. The analytical expressions for calculation of the pair interaction parameter using the binodal and liquidus curves were obtained. The pair interaction parameters of polymers and their dependences on the temperature and molecular weight were determined. The pair interaction parameter was shown to decrease with increasing the molecular weight of the oligomer component, approaching asymptotically a limiting value, which characterizes the interaction of the high molecular-weight PDMS and PDES. It was shown that the phase equilibria in the PDMS—PDES systems can be predicted quantitatively and qualitatively.     

卤素取代甲苯的合成及其在Co(OAc)2－Mn(OAc)2－NaBr催化下的液相氧化反应

合成了3-氟甲苯和另外5个氯或溴取代的3-氟甲苯,以Co(OAc)₂·4H₂O、Mn(OAc)₂·4H₂O和NaBr为催化剂用液相氧化反应将其氧化为相应的卤代苯甲酸。该反应产率较高,所得卤代苯甲酸纯度好。6个卤代的3-氟甲苯及6个相应的卤代苯甲酸其结构经IR、UV、¹H NMR、MS和元素分析所确证。     

2-(2-喹啉偶氮)-5-二乙氨基苯甲酸固相萃取光度法测定环境水样中的镍

用2－（2－喹啉偶氮）－5－二乙氨基苯甲酸（QADEAB）与镍的显色反应及Waters Porapak^R Sep-Park固术萃取小柱对显色络合物的固相萃取，建立了测定水样中μg/L级镍的新方法。水样中的镍在pH=8.0的硼酸－磷酸二氢钾缓冲介质中和Tween 80存在下与QADEAB反应生成2：1稳定有色络合物，该络合物可用Waters Porapak^R Sep-Park固相萃取小柱富集，用乙醇洗脱后用光度法测定，可测定水样中μg/L级的镍。方法用于几种环境水样分析，结果令人满意。     

Utilization of the p-nitrobenzyloxycarbonyl (pNZ) amine protecting group and pentafluorophenyl (Pfp) esters for the solid phase synthesis of spiroligomers

Spiroligomers are a class of peptidomimetics that connect interchangeable, stereochemically pure, cyclic monomers through pairs of amide bonds to form diketopiperazines between the monomers. This enables them to adopt predictable and programmable structure due to the rigidity of the final molecule. We present a new method for the solid phase synthesis of highly functionalized spiroligomers that incorporates the use of the p-nitrobenzyloxycarbonyl (pNZ) as a temporary amine protecting group and the pentafluorophenyl ester for monomer activation. This new method allows for the synthesis of spiroligomers with higher purity and increased yields when compared to previous methods. This improved method of synthesis of functionalized spiroligomers will facilitate the development of applications as catalysts, therapeutics and membrane channels.     

Efficient Synthesis of Poly(acrylic acid) in Aqueous Solution via a RAFT Process

The direct polymerization of acrylic acid (AA) in aqueous solution for high molecular weight by means of living radical polymerization is still difficult. Here, AA was polymerized homogeneously in water by a reversible addition-fragmentation transfer polymerization (RAFT) in the presence of a water-soluble trithiocarbonate as a RAFT agent. Various ratios [AA]:[RAFT agent] were investigated to aim at different molecular weights. The polymerization exhibited living free-radical polymerization characteristics at different ratios [AA]: [RAFT agent]: controlled molecular weight, low polydispersity and well-suited linear growth of the number-average molecular weight, M _n with conversion. The chain transfer to solvent or polymer was suppressed during the polymerization process, thus high linear PAA with high molecular weight and low PDI can be obtained. Moreover, using the generated PAA as a macro RAFT agent, the chain extension polymerization of PAA with fresh AA displayed controlled behavior, demonstrated the ability of PAA to reinitiate sequential polymerization.     

聚天冬氨酸硅质固定相的研制及应用

D，L-天冬氨酸在浓磷酸的存在下加热聚合生成聚琥珀酰亚胺，此产物能与氨丙基硅胶快速反应生成聚琥珀酰胺硅胶，然后再水解生成聚天冬氨酸硅质固定相．并对反应条件进行了优化、实验表明，聚天冬氨酸固定相对蛋白质有较好的分离能力和选择性．     

脱氧核糖核酸-聚胺基酰胺树状间隔臂-(二氧化锆-脲醛树脂)亲和色谱固定相的合成及其应用

报道了一种高效液相亲和色谱固定相的合成方法。以３－５μｍ的非多孔二氧化锆与脲醛树脂（ＵＴＲ）复合物微球用作高效液相亲和色谱固定相的基体,并用扫描电子显微镜检验该基体的结构和粒径。用此基体末端的酸胺基团为核心,分别与丙烯酸甲酯、乙二胺重复进行三次马氏加成反应和胺化反应,就形成末端为胺基的聚胺基酰胺（ＰＡＭＡＭ）星型树状间隔臂。用１３Ｃ固体核磁共振检测了树状间隔臂的拓扑结构。此间隔臂用丁二酸进行丁二酰化,并在１－乙基－３－（３－二甲基氨丙基）碳化二胺（ＥＤＡＣ）的存在下用Ｎ－羟基丁二酰亚胺（ＮＨＳ）活化,最后与配位体脱氧核糖核酸（ＤＮＡ）键合,并用紫外分光光度法测定了配位体容量。从而制备了一种［ＤＮＡ（ＰＡＭＡＭ）－（ＺｒＯ２－ＵＦＲ）］高效液相亲和色谱固定相。通过优化色谱柱操作参数,其已用于蛋白质的分析和核糖核酸（ＲＮＡ）碎片的分离。     

Making High Selective Molecule Imprinting Polymer (MIP) In Polar Solvent

IntroductionMoleculeimprintingtechnologyhasmadegreatprogressinmakingchiralstationaryphasewithpredeterminedchiralselectivityagainstenantiomerssuchasaminoacidandtheirderivatives;sugarandtheirderivatives;naproxenandmethylbenZylamine'-'.Functionalmonomer...     

温度与pH快速响应性P(NIPAM-co-AAc)水凝胶的制备及其性能

以氯化钠水溶液作为反应介质,成功制备了温度与pH快速响应性聚(N-异丙基丙烯酰胺-co-丙烯酸)[P(NIPAM-co-AAc)]水凝胶,研究了氯化钠水溶液的浓度对凝胶性能的影响.通过红外光谱(FT-IR)、扫描电镜(SEM)、测溶胀比对凝胶性能进行了表征.结果表明:凝胶具有相同的化学组成与结构,但具有不同的微观形态;随着反应介质中氯化钠浓度的增加,凝胶在20℃蒸馏水中的平衡溶胀比增大,并表现出较强的温度与pH敏感性以及较快的去溶胀速率.     

The Crystallization and Melting Processes of Poly(L-lactic acid)

A throughout investigation of crystallization and melting behavior of poly(L -lactic acid) is detailed in this contribution. Crystallization analyses, conducted in both isothermal and non-isothermal conditions, revealed the occurrence of a sudden acceleration in phase transition rate in the temperature range between 100 and 118 °C. This unusual increase, due to very high rates of spherulite growth, seems not related to morphological changes of PLLA spherulites, nor to unexpected variations in nucleation rate. DSC analyses disclosed multiple melting behavior of PLLA, depending on crystallization temperature. At low temperatures the very high crystallization rates lead to the achievement of low values of crystalline degree, with formation of small and/or defective crystals, which have a large tendency to reorganize into more stable structures during the heating scan that leads to complete fusion. The multiple melting process of PLLA was also analyzed at different heating rates.     

Structure and compatibility of poly(vinyl alcohol)-silk fibroin (PVA/SA) blend films

The structure and compatibility of poly(vinyl alcohol)-silk fibroin (PVA/SF) blend films were analyzed by differential scanning calorimetry (DSC), thermomechanical (TMA) and thermogravimetric (TGA) analysis, x-ray diffractometry, and scanning (SEM) and transmission (TEM) electron microscopy. DSC curves of PVA/SF blend films showed a major endothermic peak at 220°C, along with a peak at 280°C. These endotherms were assigned to the thermal decomposition of the ordered PVA elements and to the thermal degradation of silk fibroin, respectively. The PVA/SF blends behaved in a manner intermediate to the pure components, as suggested by both contraction expansion and sample weight retention properties recorded by TMA and TGA measurements. The IR absorption spectra of the blends were identified as purely a composite of the absorption bands characteristic of both PVA and SF pure polymers. The X-ray diffraction patterns of PVA/SF blends showed overlapping spacing due to PVA and SF. A dispersed phase formed by spherical particles of 3–7 μm diameter was observed by SEM and TEM. All these findings suggest that PVA and SF are incompatible. © 1994 John Wiley & Sons, Inc.     

Preparation of a new chiral stationary phase for HPLC based on the (R)- 1-phenyl-2-(4-methylphenyl)ethylamine amide derivative of (S)-valine and 2-chloro-3,5-dinitrobenzoic acid: enantioseparation of amino acid derivatives and pyrethroid insecticides

A novel chiral stationary phase (CSP) for HPLC was prepared by bonding (R)-1-phenyl-2-(4-methylphenyl)ethylamine amide derivative of (S)-valine to aminopropyl silica gel through a 2-amino-3,5-dinitro-1-carboxamido-benzene unit. The CSP was used for the separation of some amino acid derivatives and pyrethroid insecticides by chiral HPLC. Satisfactory baseline separation required optimization of the variables of mobile phase composition. Use of dichloromethane as modifier in the mobile phase gave baseline separations of amino acid derivatives. The two enantiomers of fenpropathrin and four stereoisomers of fenvalerate were baseline separated using hexane-dichloromethane-ethanol as mobile phase. The results show that the enantioselectivity of the new CSP is better than Pirkle type 1-A column for these compounds. Only partial separations were observed for the stereoisomers of cypermethrin and cyfluthrin, which gave even and eight peaks, respectively.     

Zur Identifizierung von Sulfonamiden (SA) mit Hilfe von Gruppen-Reagentien und der Papierchromatographie (P-chr)

Ohne Zusammenfassung     

聚(乙烯基对苯二甲酸二烷基酯)的非寻常相转变

以聚(乙烯基对苯二甲酸二烷基酯)(PDAVT)为对象,用热分析、X射线衍射、流变及固体核磁共振等方法考察了甲壳型液晶高分子中存在的"低温无序、高温有序"的非寻常相行为.实验证明,在升温过程中,烷基基团为丁基、己基和辛基的PDAVT(P4、P6和P8)可从无定形态发育出柱状(Col)液晶相,导致在高温区体系模量升高.降温时P6和P8可完全回到无定形态,表现出典型的"各向同性相重入"行为.PDAVT液晶相畴的生长具有一维生长的特点,是成核控制的,升高温度可加快Col相的形成.固体核磁共振实验表明,样品从无定形态转变为Col相的过程与侧链运动性的不断加强有密切关系.我们也初步探索了剪切场或拉伸场对液晶转变的影响,发现当温度不高时,剪切或拉伸既不改变液晶转变温度,也没有提高液晶态样品的液晶化程度.综合分析多方面的实验结果可以看出,PDAVT的非寻常相行为是熵主导的.侧链的加速运动会增强"甲壳效应",Col相是侧链熵最大化的结果.