In situ self-assembly synthesis of gold nanoparticle arrays on polystyrene microspheres and their surface plasmon resonance

Gold (Au) nanoparticle arrays with tunable morphology and optical characteristics were synthesized by in-situ self-assembly process that occurred on the surface of aniline-modified polystyrene (PS) microspheres. The method can be used to control the growth of both single and aggregated Au nanoparticle arrays on PS microsphere surface. This method could also be adapted for synthesis of other noble metals hybrid materials, which opens exciting opportunities for their practical applications.     

荧光增白剂28的光漂白特性研究

荧光增白剂28(F-28)为欧盟标准EN 648-2006《与食品接触的纸和纸板-荧光增白剂牢度的测定》中判断食品接触材料所含荧光增白剂是否向食品中迁移的标样。我们发现,在规定的波长365nm紫外光激发下,F-28所制成的标样会出现光漂白现象。因此,本文对F-28的光漂白特性进行研究。结果表明,紫外辐照时间为60s时,四级(3mg/L)、三级(8mg/L)、二级(31mg/L)、一级(125mg/L)滤纸和玻纤的最大荧光值衰减率分别为0.16%、0.29%、0.92%、0.44%和2.59%、1.99%、0.49%、3.14%;当辐照时间延长到1800 s时,最大荧光值衰减率分别增加为4.67%、4.22%、5.51%、2.75%和35.37%、39.78%、28.09%、39.38%。因此,在对食品接触材料是否含有荧光增白剂以及是否迁移的测试中,必须考虑光漂白因素。同时,滤纸作为迁移实验载体,在降低光漂白和稳定性方面比玻纤更具优势。     

Distinct Stepwise Reduction of a Nickel?Nickel‐Bonded Compound Containing an α‐Diimine Ligand: From Perpendicular to Coaxial Structures

A nickel? nickel‐bonded complex, [{Ni(μ‐L^.?)}₂] ( 1 ; L=[(2,6‐iPr₂C₆H₃)NC(Me)]₂), was synthesized from reduction of the LNiBr₂ precursor by sodium metal. Further controllable reduction of 1 with 1.0, 2.0 and 3.0 equiv of Na, respectively, afforded the singly, doubly, and triply reduced compounds [Na(DME)₃] ? [{Ni(μ‐L^.?)}₂] ( 2 ; DME=1,2‐dimethoxyethane), [Na(Et₂O)]Na[(L^.?)Ni? NiL^2?] ( 3 ), and [Na(Et₂O)]₂Na[L^2?Ni? NiL^2?] ( 4 ). Here L represents the neutral ligand, L^.? denotes its radical monoanion, and L^2? is the dianion. All of the four compounds feature a short Ni? Ni bond from 2.2957(6) to 2.4649(8) Å. Interestingly, they display two different structures: the perpendicular ( 1 and 2 ) and the coaxial ( 3 and 4 ) structure, in which the metal? metal bond axis is perpendicular to or collinear with the axes of the α‐diimine ligands, respectively. The electronic structures, Ni? Ni bonding nature, and energetic comparisons of the two structure types were investigated by DFT computations.     

仿细胞外层膜结构修饰交联壳聚糖的研究

采用溶液自由基聚合,合成甲基丙烯酰氧乙基磷酰胆碱(MPC)-甲基丙烯酰氧丙基三甲氧基硅(TSMA)二元共聚物(PMT82),将其涂覆在戊二醛交联壳聚糖(CS-GA)表面,通过三乙胺蒸汽催化处理获得具有仿细胞外层膜结构(CS-GA-PMT82b)的表面.用动态接触角(DCA)、X-射线光电子能谱(XPS)对改性后交联壳聚糖表面的亲疏水性、元素组成等进行表征,并通过血小板黏附实验对其抗凝血性进行评价.研究结果表明,这种利用涂覆催化交联的方式将含有三甲氧基硅可交联基团的磷酰胆碱聚合物交联固定在壳聚糖表面,获得了较为稳定的仿细胞外层膜结构的CS-GA-PMT82b涂层表面.与壳聚糖相比,改性后壳聚糖的血小板黏附显著减少,抗凝血性能显著提高.这种改善材料的方式有望成为生物医用材料表面改性领域的有效的新手段.     

反相悬浮聚合法制备球状卡波树脂的研究

以偶氮二异丁脒盐酸盐(V50)作为引发剂,失水山梨醇硬脂酸酯(Span60)和聚二甲基硅氧烷PEG-7磷酸酯为复合分散剂,蔗糖烯丙基醚和三甲基丙基聚氧乙烯(15)醚三丙烯酸酯为复合交联剂,丙烯酸为单体,正已烷为反应介质,采用反相悬浮聚合方法制备了球状卡波树脂.用光学显微镜和扫描电镜分别对聚合反应的成粒过程和产物的形貌进行了研究.结果表明,聚合体系呈现典型的悬浮聚合相态特征,并获得了堆积密度较高(0.65 g/cm3)的球状卡波树脂.聚合反应动力学研究结果表明,该反相悬浮聚合的聚合速率对单体浓度和引发剂浓度的反应级数分别约为1.36和0.70;聚合反应的表观活化能为78.0 kJ/mol.交联剂对卡波树脂的性能有重要的影响,通过适度交联可提高产物的增稠效率及其抗剪切性能.     

Transition metal-free synthesis of primary amides from aldehydes and hydroxylamine hydrochloride

Primary aromatic amides can be synthesized from aldehydes and hydroxylamine hydrochloride in the presence of Cs₂CO₃. Various aromatic aldehydes (include some heteroaromatic aldehydes) are able to generate the corresponding aromatic amides in moderate to excellent yields.     

C?H Functionalization/Asymmetric Michael Addition Cascade Enabled by Relay Catalysis: Metal Carbenoid Used for C?C Bond Formation

A combination of either ruthenium(II) or rhodium(II) complexes and quinine‐derived squaramide enables 3‐diazooxindoles, indoles, and nitroalkenes to undergo highly efficient asymmetric three‐component reactions, thus affording optically active 3,3′‐bis(indole)s through a consecutive C C bond‐forming sequence, which turned out to be applicable to the facile total synthesis of (−)‐folicanthine.     

4,5-Dicyanoimidazole-promoted synthesis of dinucleoside polyphosphates and their analogs

A general and efficient P(V)–N activation method for the preparation of symmetrical and asymmetrical dinucleoside polyphosphates (Np_nN′s, n=2–4) and P²,P³-CX₂-dinucleoside tetraphosphates (X=H, F, and Cl) has been established. Twenty-two dinucleoside polyphosphates and their phosphonate analogs were synthesized from nucleoside 5′-phosphoropiperidates with 4,5-dicyanoimidazole as the activator in good to high yields.