壳聚糖-两性聚氨酯接枝共聚物的制备

利用壳聚糖大分子链上的－OH和－NH2基团与两性聚氨酯预聚体的端－NCO基团反应，把两性聚氨酯链接枝到壳聚糖分子链上，为聚电解质及纳米胶体粒子间的组装，复合性质的研究提供模型化合物，红外光谱，热分析方法初步研究表明，采用上述方法能够制备出APU－壳聚糖接枝共聚物，但产物是壳聚糖与接枝共聚物的混合物，研究发现，这种接枝共聚物在盐酸水溶液中呈胶束形态，而且具有独特的流变性。     

粘度法研究壳聚糖与两性聚氨酯胶束间的相互作用

通过粘度法考察了壳聚糖(CS)在盐酸水溶液中与表面带有正电荷的两性聚氨酯(APU)胶束的相互作用，并研究了小分子盐浓度、pH及不同混合方式对复合体系粘度的影响．结果表明：在壳聚糖／APU盐酸混合体系中，较高浓度下APU胶束与壳聚糖分子间的静电斥力作用导致壳聚糖大分子链的伸展，使体系粘度提高，同时降低了壳聚糖溶液对电解质、pH的敏感性；不同混合过程导致壳聚糖大分子构像及其与APU组装、复合形态有很大差别，使混合体系流变性表现出明显的不同．     

氨乙基氨丙基聚二甲基硅氧烷改性水性聚酯型聚氨酯的研究

由聚酯二元醇、异佛尔酮二异氰酸酯和二羟甲基丙酸合成聚氨酯预聚体，以氨乙基氨丙基聚二甲基硅氧(AEAPS)为扩链剂，制备了AEAPS改性聚氨酯水分散液。与未改性的聚氨酯水分散液相比，AEAPS改性聚氨酯水分散液的粒径增大，但粒径分布和表面张力基本不变，说明疏水的聚二甲基硅氧烷侧链被包裹于分散颗粒的内部；此外，改性聚氨酯水分散液的冻融稳定性显著增强。AEAPS改性聚氨酯水分散液成膜后，吸水率明显下降，水在膜表面的接触角增加，400℃时热失重下降，具有良好的疏水性和耐热性。     

一种纳米氧化锌复合生物基水性聚氨酯的合成和性能研究

以自制的生物基水性聚氨酯(APU)及纳米氧化锌(ZnO)为原料制备了APU/ZnO复合材料,并通过红外光谱(FT-IR)、热重(TG)、紫外(UV)、透射电镜(TEM)和扫描电镜(SEM)等手段对复合材料的性能进行了表征。TEM和SEM照片显示,制得的新型纳米ZnO的尺寸为200 nm左右,可较均匀地分散在APU体系中。TG测试结果表明添加了少量纳米ZnO的复合材料的耐热性有了明显提高。同时测试结果表明,少量纳米ZnO粒子的加入对APU有很好的增强和增韧效果,且具有一定的抗菌性和抗紫外性能。     

两性高分子与小分子及大分子的相互作用（上）

两性高分子是分子链上同时含有正负电荷基团的一类高聚物,具有独特的性质.本文就合成两性高分子与小分子物质(金属离子、表面活性剂、染料、有机探针等)及大分子化合物(聚电解质、蛋白质)的络合过程及影响络合的因素进行了综述.     

两性高分子的溶液性质

两性高分子是分子链上同时含有正负电荷基团的一类高聚物、具有独特的溶液性质。本文就两性高分子等电点的构象状态、影响等电点的因素、两性高分子的溶解性以及高分子结构和组成、ｐＨ、溶液离子强度、混合溶剂、温度对流体力学行为的影响进行了综述。     

苯乙烯在阴离子型聚氨酯纳米水分散液中聚合过程的研究

采用自乳化法制备出阴离子聚氨酯纳米水分散液,以其作为乳化剂使苯乙烯单体在其中进行聚合,制备出不同聚苯乙烯与聚氨酯质量比的阴离子型PS/PU纳米复合物水分散液;对苯乙烯单体的聚合过程进行了研究;采用光子相关谱仪和透射电镜对其微观结构、粒径及其分布进行了测试,结果表明,该方法能够制备出稳定的具有核壳结构的PS/PU纳米复合物水分散液,但当苯乙烯单体浓度增大到一定程度(PS/PU质量比为50∶100)时,粒子不稳定而发生聚集.     

利用点击化学反应修饰聚氨酯

合成了2,2-丙炔基-1,3-丙二醇(DPPD),将其作为扩链剂引入聚氨酯(PU)主链分子中,获得了一种主链带有炔基的可降解聚氨酯材料,并通过叠氮基团与炔基间的点击化学反应,将模型分子引入到聚氨酯分子链上.1H NMR图谱中δ2.03的峰及红外图谱中2138 cm-1处的峰证实炔基引入了聚氨酯分子链;1H NMR图谱δ7.91处的峰表明采用点击化学方法将苄基叠氮分子引入了聚氨酯分子主链.当扩链系数分别为1,0.7和1[70%DPPD+30%1,3-丙二醇(PDO)]时,最终产物中炔基含量分别为0.396,0.235和0.197 mmol/g.细胞毒性实验结果表明,炔基的引入对细胞活性没有影响.     

疏水改性聚电解质的荧光探针光谱

流水改性聚电解质或聚皂（PolysoaP）是在亲水性聚电解质的侧链或主链上键合少量的强流水性基团的聚合物l'，'］流水基团一般采用长链烷基（通常碳原子数大于刚＊一、也有用硅氧烷、氟碳化合物进行疏水改性问由干这种聚合物分子链上带有两性亲媒基团，因此，又被称为高分子表面     

表面增强拉曼散射光谱研究聚苯胺纳米棒的构象转变

采用电化学沉积法制备了聚苯胺(Polyaniline,PANI)纳米棒、树枝状银和纳米颗粒银基体。并利用表面增强拉曼散射光谱技术(Surface-enhanced Raman Scattering,SERS)研究了PANI纳米棒的分子链在Ag金属表面的构象变化。实验结果表明由于Ag金属表面的等离子共振效应,PANI分子中N原子的孤对电子与Ag的自由电子产生共轭效应,使得PANI分子链上的电荷重新分布,结果 C—H面内弯曲振动频率和C—C键的伸缩频率向低波数方向移动(蓝移);拉曼散射频率增强的基团在金属表面倾向垂直于分子链的主轴,拉曼散射频率减弱的基团在金属表面倾向平行于分子链主轴。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.