羧甲基壳聚糖磁性纳米粒子的合成及应用

通过合成油酸修饰的Fe3O4纳米粒子和羧甲基壳聚糖直接包埋油酸修饰的Fe3O4纳米粒子的两步合成法制备了羧甲基壳聚糖磁性纳米粒子。采用透射电子显微镜、傅里叶变换红外光谱、振动样品磁强计和同步热分析测试技术对制备的羧甲基壳聚糖磁性纳米粒子进行了表征。所得磁性纳米粒子呈规则球形,粒径约为10 nm;表面含羧基,且具有很好的顺磁性和稳定性。考察了羧甲基壳聚糖磁性纳米粒子对阿霉素的载药量和对阿霉素在磷酸盐缓冲溶液中的缓释性能。结果表明,磁性纳米粒子对阿霉素展示了较高的载药量(91.8 mg/g),结合了阿霉素的磁性复合物对阿霉素的缓释作用明显,说明制备的羧甲基壳聚糖磁性纳米粒子有望作为治疗肿瘤的纳米磁靶向药物输送载体。     

以L-组氨酸为模板仿生合成针状纳米碳酸钙

依据仿生合成原理, 以L-组氨酸为有机基质, 无水氯化钙和无水碳酸钠为原料, 通过简单的复分解反应制备出了平均直径约为80 nm, 长径比约为12∶1的针状纳米碳酸钙晶体. 利用高分辨扫描电子显微镜(FESEM)、X射线衍射仪(XRD)、傅里叶红外光谱议(FTIR)对产物进行了表征, 结果表明, 在不添加有机基质的溶液中得到立方状微米级的碳酸钙晶体, 添加L-组氨酸后得到针状纳米级的碳酸钙晶体, 并对L-组氨酸在仿生合成针状纳米碳酸钙过程中的作用机理进行了初步探讨.     

O-羧甲基壳聚糖纳米微粒制备及对Ni~(2+)吸附研究

将壳聚糖与氯乙酸反应,通过控制反应条件制备了取代度为0.71的O-羧甲基壳聚糖,将改性后的O-羧甲基壳聚糖与多聚磷酸钠反应,制备了粒径分布在370-710nm的O-羧甲基壳聚糖纳米微粒,透射电镜观察表明该微粒呈球状,平均粒径为450nm.在此基础上研究了O-羧甲基壳聚糖纳米微粒对工业电镀镍废水Ni~(2+)吸附性能,考察了溶液pH、Ni~(2+)起始浓度、平衡吸附时间、粒径等因素的影响,结果表明:O-羧甲基壳聚糖微粒最佳吸附条件是Ni~(2+)溶液pH为8.0、Ni~(2+)溶液起始浓度为33.28mg/ml、平衡吸附时间为0.5h、粒径较小的O-羧甲基壳聚糖纳米微粒对Ni~(2+)的吸附量要大于粒径较大的吸附量.     

(2-羟基-3-丁氧基)丙基-羧甲基壳聚糖的合成及表面性质

(2-羟基-3-丁氧基)丙基-羧甲基壳聚糖的合成及表面性质;壳聚糖衍生物; (羟基丁氧基)丙基-羧甲基壳聚糖;表面活性;表面压     

天冬氨酸调控糖果状碳酸钙的仿生合成及性能

利用仿生合成原理,选取天冬氨酸作为诱导剂,采用沉淀反应法制备出糖果状球霰石型碳酸钙粒子,并对其结构和性能进行了表征.考察了反应温度、诱导剂用量和反应时间等对碳酸钙粒子晶型和形貌的影响，探讨了其反应原理.结果表明,所得碳酸钙粒子荧光性增强.此方法对碳酸钙的仿生合成与改性研究具有一定的指导意义.     

交联羧甲基壳聚糖对铅离子的吸附研究

以壳聚糖为原料,先在氨基上引入羧甲基制备出N-羧甲基壳聚糖,再和环氧氯丙烷发生交联反应,合成出新型交联羧甲基壳聚糖,FTIR表征其结构。研究了交联羧甲基壳聚糖对Pb2+的吸附性能,探讨了交联剂用量、铅离子溶液的pH值、温度、吸附时间等因素对其吸附性能的影响,并考察了交联羧甲基壳聚糖对铅离子吸附动力学和热力学实验。实验结果表明,交联羧甲基壳聚糖对铅离子的吸附量优于壳聚糖,平衡吸附量可达297.6 mg/g。交联羧甲基壳聚糖对铅离子的吸附符合准二级动力学模型和Langmuier等温吸附,吸附主要依靠结构中的羧基和氨基基团。     

羧甲基壳聚糖/有机累托石纳米复合材料及其药物缓释性能研究

利用简单的溶液插层法制备了羧甲基壳聚糖/有机累托石纳米复合材料,其中累托石(REC)用十六烷基三甲基溴化铵进行改性.用X-射线衍射(XRD)、红外光谱(FTIR)和扫描电镜(SEM)表征了该纳米复合材料的微观结构和形态,实验表明羧甲基壳聚糖插层进入了累托石层间,增大了累托石的层间距,并且累托石均匀地分布在羧甲基壳聚糖基体中.以牛血清蛋白(BSA)为药物模型,研究了纳米复合材料与海藻酸钠形成的微球的药物缓释性能.结果显示,该微球对药物的包封率及缓释性能与纯羧甲基壳聚糖微球相比都有较大改善,包封率从56%提高到86%,药物缓释时间从24 h上升到72 h.并且纳米复合材料/海藻酸钠微球的释药具有pH响应性,在pH为1.2的条件下释药慢,而在pH为7.4时释药快,可用于小肠或结肠定位缓释系统.因此,羧甲基壳聚糖/有机累托石纳米复合材料很有潜力作为药物载体.     

磁性羧甲基壳聚糖吸附分离孔雀石绿的研究

采用水热法制备Fe3O4磁性纳米粒子,再经反相乳液交联法,用戊二醛将羧甲基壳聚糖与Fe3O4结合。此方法制备的磁性羧甲基壳聚糖用TEM,FT-IR和PPMS表征,并用于孔雀石绿的吸附分离。对磁性羧甲基壳聚糖的吸附性能进行了分析,考察了动力学吸附方程和等温吸附线类型,讨论了不同p H值下磁性羧甲基壳聚糖对孔雀石绿的吸附情况,并探讨了制备的吸附剂的可重复利用性,在使用5次后,经10%的乙酸甲醇溶液解吸的磁性羧甲基壳聚糖对孔雀石绿的吸附率仍能达到94.97%。     

均匀大颗粒球形碳酸钙的仿生合成

依据仿生矿化原理,采用难溶性CaSO4作为钙源,以柠檬酸钠为模板剂合成出了均匀大颗粒球形碳酸钙晶体,用X射线粉末衍射(XRD)分析、扫描电子显微镜(SEM)、傅立叶变换红外吸收光谱(FTIR)和热重分析等测试技术对所得碳酸钙样品进行了表征,探讨了其合成机理. 研究表明,柠檬酸钠对碳酸钙的晶形具有调控作用,在柠檬酸钠质量浓度为0.9%的条件下,能合成出大小均匀、分散性好、粒度为10～15 μm的大颗粒球形碳酸钙晶体.     

低碱法制备羧甲基壳聚糖及表征

低碱法制备羧甲基壳聚糖及表征;壳聚糖;羧甲基壳聚糖;取代度;特性粘度;低碱法     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

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%).     

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.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.