树枝状高分子简介2008年9月从多官能团内核出发，通过支化基元逐步重复生长, 形成具有高度支化结构的树枝状三维大分子。树形大分子的介绍 Tomalia 在1985 年利用发散法首次合成树形聚(酰胺胺) 型大分子 Hawker等人在1989年利用收敛法合成树形冠醚大分子 Balzani 等人在1992 年首次报道了有机过渡金属树形大分子 Percec 等人在1995年首次报道了液晶型的树形大分子化合物树形大分子的发展和研究现状q 目前，二十多类，200多种树形大分子被合成出来树形大分子的合成方法分散法收敛法核心出发逐步引入单体。代数高，分子量大;易有缺陷，产物与反应物不易分离。构造外围分支，由核心连接。空间位阻，速率慢; 缺陷少，产物与反应物易分离。I. Tomalia. J. Polymer. 1985, 17, 117. C. Hawker, J. Frechet. J. Am. Chem. Soc. 1990, 112, 7638.C.Dufes, I.F. Uchegbu, A.G. Schatzlein. Adv Drug Deli Rev. 2005, 57, 2177PAMAM(聚酰胺- 胺)合成过程中心有核 内部有空腔，大量支化单元 表面均匀分布可修饰的官能基团体积、形状、功能基以及分子量都 可以在分子水平精确控制-单分散性高度支化，具有规整，精致的完美结构, 高代数呈球形。 纳米级尺寸。良好的溶解性，低的黏度。树形大分子的结构特点和性质低黏度、高溶解性纳米层、聚合液晶、超分子内部受体封装胶团能量和电子转移分子识别催化剂、传感器氧化还原特性外部受体树形大分子的结构特点和性质A.M. Caminade. Laboratoire de Chimie de Coordination du CNRS 205, route de Narbonne, 31077 Toulouse cedex 4, FRANCE, 2005树形大分子的应用v 超分子化学的应用v 催化剂方面的应用v 生物医学方面的应用v 光学方面的应用v 其他方面的应用超分子的应用 主-客体体系V. Balzani, F. Vgtle .C. R. Chimie. 2003, 6, 867Fig. 1. Schematic representation of (a) a conventional fluorescent sensor and (b) a fluorescent sensor with signal amplification. Open rhombi indicate coordination sites and black rhombi indicate metal ions. The curved arrows represent quenching processes. In the case of a dendrimer, the absorbed photon excites a single fluorophore component, i.e. quenched by the metal ion, regardless of its position.超分子的应用 分子自组装Y. Liu, M. Zhao, D.E. Bergbreiter. J. Am. Chem. Soc. 1997, 119, 8720Fig.2. Schematic illustration of the pH-switchable “On/Off” function of the composite film. The polyamine dendrimer units are covalently attached to the Gantrez polymer network. At high pH the film has a net negative charge that excludes anions but passes cations; at low pH it is positively charged and excludes cations but passes anions; and at intermediate pH, it passes both cations and anions.催化剂方面的应用v 纳米尺寸，形成纳米微环境v 催化活性中心有可变性v 减少金属催化剂流失v 分子结构可精确控制Fig. 3. Shape-selective olefin epoxidation using dendrimers with a manganese(iii) porphyrin core as catalystsP. Bhyrappa, J. K. Young, J. S. Moore, K.S. Suslick. J. Mol Catal A. 1996, 113. 109催化剂方面的应用Fig.4. Epoxidation results for the intermolecular mixture of alkenes.The ratios of the epoxides are normalized with respect to corresponding Mn(TPP)+ values. Errors are estimated at (5% relative.substrate/dendrimera conversion, % turnover no.353 to 1 90 318 1760 to 1 92 1619 3530 to 1 94 3318 17600 to 1 99 17400Fig.5 A unimolecular reverse micelle that efficiently catalyzes the elimination of tertiary halides. The nonpolar corona (yellow) shields the polar interior (blue) of hydroxyl functionalities, which are able to stabilize the carbocation intermediate.M.E. Piotti, F. Rivera, R. Bond, C.J. Hawker, J. M. J. Frechet. J. Am.Chem. Soc. 1999, 121, 9471催化剂方面的应用Table 1. Effect of Changing the Dendrimer Structure and Concentration on the Yield and Turnover Number for the E1 Elimination Reaction (Reaction performed for 43 h at 70 oCa The molar ratio.Fig.6 Competitive Hydrogenations of 3-Cyclohexene-1-methanol and CyclohexeneUsing Various Pd Catalysts .Reaction conditions: 3-cyclohexene-1-methano l 0.5 mmol, cyclohexene 0.5 mmol, catalyst 5.0 mol of Pd, toluene 12.5 mL, H2 1 atm, 30 oC.树状大分子封装金属粒子（1）小于4 nm纳米粒子，比表面积大、催化效率高（2）表面基团控制溶解性（3）能很好的稳定纳米粒子，并创造纳米微环境（4）能再生使用M. Ooe, M. Murata, T.Mizugaki, K. Ebitani, K. Kaneda. Nano Lett. 2002, 2, 999催化剂方面的应用生物医学的应用Fig.7 approaches for design of drug delivery systems.药物载体v内部空腔和结合点可 以携带药物。v高密度表面基团经过 修饰，改变水溶性和靶 向作用。v毒性较低，通过扩散 和生物降解实现药物释 放。v分子设计实现生物相 溶性和降解性。 R. Duncan, L. Izzo. Advanced Drug Delivery Reviews. 2005, 57, 2215外层用聚乙二醇修饰的聚芳醚类树形单分子胶束，疏水内层和亲水外层， 在水溶液中有很强的增溶能力，每个胶束能包容9-10个疏水性消炎痛药物 分子，具有明显的缓释作用。Fig. 9. Structure of the G2 dendritic unimolecular micelle.药物载体M. Liu, K. Kono , J.M.J. Frechet. Journal of Controlled Release. 2000, 65, 121Fig. 8. In vitro release profile of indomethacin from the G3 dendritic unimolecular micelle. 病毒：它的体积也小,转染效率就相对较低. 核酸：容易受到细胞毒素的损害。 质粒DNA ：易受到血浆和血清蛋白的降解. 脂质体：它有细胞毒性反应。基因载体U. Boas, P.M.H. Heegaard. Chem. Soc. Rew. 2004, 33, 43. D.A. Tomalia. Prog. Polym. Sci. 2005, 30, 294生物医学的应用Fig.10. Top row: Three dimensional depiction of conformational change of an amino-terminated PAMAM dendrimer at increasing pH . Middle row: Two-dimensional depiction of the conformational change of an amino- terminated PAMAM dendrimer upon increasing pH.Fig. 9 The close dimensional size (nm) of selected proteins to respective generations of ammonia core-dendri PAMAM-(NH2)z dendrimer.v与许多重要蛋白质和生物组装分子的大小及形状很匹配。vPAMAM生理条件下为聚阳离子,且有很好的溶解性，末端胺基很容易与DNA 中的带负电的磷酸基相互作用。v内部有空腔，促进DNA结合的复合物的稳定性。基因载体J. Dennig, E. Duncan. Reviews in Molecular Biotechnology. 2002, 90, 339.Fig. 11 Model of activated dendrimer-mediated DNA uptake.In the first step of the transfectio