with functional gradients at the microstructural level. Periodically ordered mesoporous organosilicas (PMOs) and aerogel‐like monolithic bodies with a maximum density of azide groups were prepared from a novel sol–gel precursor. The controlled and fast conversion of the azide into numerous functions by clickchemistry is the prerequisite for the implementation of manifold gradient profiles. Herein
building block comprisingsulfonicacid (R‐SO3H) is described. The degree of organic modification is not only maximal (100%), it is also proven that the novel material exhibits superacid properties. Furthermore, an aerosol assisted method is applied for generating this material in the form of mesoporous, spherical nanoparticles with substantial colloidal stability. Highlyacidic, high surface area materials
The synthesis and characterization of a new periodically ordered mesoporous organosilica material (PMO) containing aniline as a bridging organic building block is presented. Furthermore, the coordination of the vanadyl cation [VO]2+ to the carboxy function of a second PMO material containing benzoic acid is described. Bifunctional materials containing both mentioned functional groups in different amounts
介绍了一种新的周期性合成的介孔有机硅材料(PMO),其以苯胺为架桥有机结构单元。此外,描述了钒阳离子[VO] 2+与第二种含苯甲酸的PMO材料的羧基官能团的配位。已经制备了包含两个上述官能团的量不同的(HOOC-PhSi 2 O 3)1- x(H 2 N-PhSi 2 O 3)x的双功能材料。[VO] 2+的偶极耦合研究通过EPR光谱与苯甲酸基团配位的化合物已被用来获得有关分子尺度上孔表面结构的详细图片。作为一种可能的应用,研究了双功能材料在两步化学转化中的催化活性。钒基催化乙缩醛的裂解,然后由苯胺催化的Knoevenagel缩合。已经观察到两组的协同作用,但这不是由组之间的特殊相互作用引起的,而是由于纯粹的统计原因。
Stimuli‐Responsive Particle‐Based Amphiphiles as Active Colloids Prepared by Anisotropic Click Chemistry
magnetic response of molecules is typically weak. Vice-versa, magnetic particles with strong response to magnetic triggers are fully established in nanoscience, but they are not amphiphilic. In this work colloids with Janus architecture and ultra-small dimensions (25 nm) have been prepared by spatial control over the thiol-yne click modification of organosilica-magnetite core-shell nanoparticles. The amphiphilic
Effects of Primary and Secondary Surface Groups in Enantioselective Catalysis Using Nanoporous Materials with Chiral Walls
作者:Andreas Kuschel、Sebastian Polarz
DOI:10.1021/ja1017706
日期:2010.5.12
periodically ordered mesoporousorganosilica material (PMO) with walls exclusively made of a chiral building block is presented. The attachment of Al(III) as a Lewis acid center to the chiral group furnishes the material with catalytic activity, for instance, for the asymmetric carbonyl ene reaction. Thus, the presented materials are valuable model systems for studying the effect of the chiral surface and also
介孔材料是固定各种分子催化剂的宝贵载体。很少有报道固定化后催化剂性能提高的情况,尤其是在对映选择性合成方面。因此,了解载体表面的存在如何改变结合催化剂的性质是非常重要的。在当前的文章中,介绍了一种新的周期性有序介孔有机硅材料 (PMO),其壁完全由手性积木制成。Al(III) 作为路易斯酸中心与手性基团的连接为材料提供了催化活性,例如,对于不对称羰基烯反应。因此,所提出的材料是用于研究手性表面以及连接到网络中硅烷醇基团的相邻基团的影响的有价值的模型系统。据报道,与类似的分子参考催化剂相比,表面结合的 Al(III) 表现出明显更好的性能(更高的 ee 值)。此外,可以表明,当更大的二级基团附着在孔壁上时,ee 值会进一步增加。因此,本报告的主要结论是,对于催化剂的空间条件起关键作用的情况,将其固定在特制的介孔有机硅材料内有利于催化中心和相邻表面基团之间的协同作用。据报道,与类似的分子参考催化剂相比,表面结合的