Mondal Bijnaneswar, Mukherjee Partha Sarathi
Department of Inorganic and Physical Chemistry , Indian Institute of Science , Bangalore 560012 , India.
J Am Chem Soc. 2018 Oct 3;140(39):12592-12601. doi: 10.1021/jacs.8b07767. Epub 2018 Sep 24.
A discrete nanoscopic organic cage (OC1) has been synthesized from a phenothiazine based trialdehyde treating with chiral 1,2-cyclohexanediamine building block via dynamic imine bond formation followed by reductive amination. The cage compound has been characterized by several spectroscopic methods, which advocate that OC1 has trigonal prismatic shape formed via [2 + 3] self-assembled imine condensation followed by imine reduction. This newly designed cage has aromatic walls and porous interior decorated with two cyclic thioether and three vicinal diamine moieties suitable for binding gold ions to engineer the controlled nucleation and stabilization of ultrafine gold nanoparticles (AuNPs). The functionalized confined pocket of the cage has been used for the controlled synthesis of AuNPs with narrow size distribution via encapsulation of Au(III) ions. Inductively coupled plasma mass spectrometric (ICP-MS) analysis revealed that the composite Au@OC1 has very high (∼68 wt %) gold loading. In distinction, reduction of gold salts in absence of the cage yielded structureless agglomerates. The fine-dispersed cage anchored AuNPs (Au@OC1) have been finally used as potential heterogeneous photocatalyst for very facile and selective conversion of nitroarenes to respective azo compounds at ambient temperature in just 2 h reaction time. Exceptional chemical stability and reusability without any agglomeration of AuNPs even after several cycles of use are the potential features of this material. The composite Au@OC1 represents the first example of organic cage supported gold nanoparticles as photocatalyst.
一种离散的纳米级有机笼（OC1）已通过动态亚胺键形成，随后进行还原胺化反应，由基于吩噻嗪的三醛与手性1,2 - 环己二胺构建单元合成。该笼状化合物已通过多种光谱方法进行表征，这些方法表明OC1具有通过[2 + 3]自组装亚胺缩合形成的三角棱柱形状，随后进行亚胺还原。这种新设计的笼具有芳香壁和多孔内部，装饰有两个环状硫醚和三个邻位二胺部分，适合结合金离子以控制超细金纳米颗粒（AuNPs）的成核和稳定。笼的功能化受限口袋已用于通过封装Au(III)离子来控制合成尺寸分布窄的AuNPs。电感耦合等离子体质谱（ICP - MS）分析表明，复合Au@OC1具有非常高（约68 wt%）的金负载量。相比之下，在没有笼的情况下还原金盐会产生无定形团聚物。精细分散的笼锚定金纳米颗粒（Au@OC1）最终被用作潜在的多相光催化剂，在室温下仅需2小时反应时间就能非常容易且选择性地将硝基芳烃转化为相应的偶氮化合物。即使经过几个循环使用，AuNPs也没有任何团聚，具有出色的化学稳定性和可重复使用性，这是该材料的潜在特性。复合Au@OC1代表了有机笼负载金纳米颗粒作为光催化剂的第一个实例。
