Jang Wongi, Yun Jaehan, Ludwig Luke, Jang Su Guan, Bae Jae Young, Byun Hongsik, Kim Jun-Hyun
Department of Chemistry, Illinois State University, Normal, IL, United States.
Department of Chemical Engineering, Keimyung University, Daegu, South Korea.
Front Chem. 2020 Sep 15;8:834. doi: 10.3389/fchem.2020.00834. eCollection 2020.
This report describes strategies to increase the reactive surfaces of integrated gold nanoparticles (AuNPs) by employing two different types of host materials that do not possess strong electrostatic and/or covalent interactive forces. These composite particles are then utilized as highly reactive and recyclable quasi-homogeneous catalysts in a C-C bond forming reaction. The use of mesoporous TiO and poly(N-isopropylacrylamide), PNIPAM, particles allows for the formation of relatively small and large guest AuNPs and provides the greatly improved stability of the resulting composite particles. As these AuNPs are physically incorporated into the mesoporous TiO (i.e., supported AuNPs) and PNIPAM particles (i.e., encapsulated AuNPs), their surfaces are maximized to serve as highly reactive catalytic sites. Given their increased physicochemical properties (e.g., stability, dispersity, and surface area), these composite particles exhibit notably high catalytic activity, selectivity, and recyclability in the homocoupling of phenylboronic acid in water and EtOH. Although the small supported AuNPs display slightly faster reaction rates than the large encapsulated AuNPs, the apparent activation energies (E) of both composite particles are comparable, implying no obvious correlation with the size of guest AuNPs under the reaction conditions. Investigating the overall physical properties of various composite particles and their catalytic functions, including the reactivity, selectivity, and E, can lead to the development of highly practical quasi-homogeneous catalysts in green reaction conditions.
本报告描述了通过使用两种不具有强静电和/或共价相互作用力的不同类型主体材料来增加集成金纳米颗粒（AuNP）反应表面的策略。然后，这些复合颗粒在碳-碳键形成反应中用作高活性且可回收的准均相催化剂。介孔TiO和聚（N-异丙基丙烯酰胺）（PNIPAM）颗粒的使用使得能够形成相对较小和较大的客体AuNP，并提高了所得复合颗粒的稳定性。由于这些AuNP物理结合到介孔TiO（即负载型AuNP）和PNIPAM颗粒（即包封型AuNP）中，它们的表面被最大化以用作高活性催化位点。鉴于其物理化学性质（如稳定性、分散性和表面积）的提高，这些复合颗粒在水中和乙醇中苯硼酸的均偶联反应中表现出显著高的催化活性、选择性和可回收性。尽管小的负载型AuNP显示出比大的包封型AuNP略快的反应速率，但两种复合颗粒的表观活化能（E）相当，这意味着在反应条件下与客体AuNP的尺寸没有明显相关性。研究各种复合颗粒的整体物理性质及其催化功能，包括反应性、选择性和E，可导致在绿色反应条件下开发高度实用的准均相催化剂。
