Immobilization of molecular catalysts on solid supports via atomic layer deposition for chemical synthesis in sustainable solvents
Immobilization of molecular catalysts on solid supports via atomic layer deposition for chemical synthesis in sustainable solvents
复制标题
DOI：
10.1039/d1gc02024b
复制
发表时间：
2021-11-08
期刊：
影响因子：
9.8
通讯作者：
Vannucci, Aaron K.
中科院分区：
文献类型：
--
作者：
Ayare, Pooja J.;Gregory, Shawn A.;Vannucci, Aaron K.
均相分子催化剂因其反应特异性而受到重视，但由于最终产物分离、催化剂回收和在水存在下的不稳定性的复杂性，在制造放大方面面临挑战。通过附着到固体载体上使这些分子催化剂异质化，可以改变分子催化剂的实际用途，简化催化剂分离和回收，并通过阻碍双分子催化剂相互作用来防止催化剂分解。先前通过配体优先结合到载体上来使分子催化剂多相化的策略已经遭受了催化活性降低和催化剂浸出（损失）的问题，特别是在环境友好的溶剂如水中。在本文中，我们描述了一种方法，其中分子催化剂首先通过酸性配体连接到金属氧化物载体，然后通过原子层沉积（ALD）用金属氧化物层“封装”以防止分子从表面脱离。对于这一初步报告，这是基于充分研究的铃木碳-碳交叉偶联反应，我们证明了使用非贵金属分子催化剂在高含水量溶剂中实现催化性能的能力。所选择的催化剂由于极短的催化剂寿命而在均相条件下表现出有限的催化反应性，但是当以最佳ALD层厚度进行非均相化和固定化时，可以在主要水溶液中获得>90%的产物产率。在ALD应用和催化反应之前和之后的催化剂表征通过红外、电子顺磁共振和X射线光谱实现。
Homogeneous molecular catalysts are valued for their reaction specificity but face challenges in manufacturing scale-up due to complexities in final product separation, catalyst recovery, and instability in the presence of water. Heterogenizing these molecular catalysts, by attachment to a solid support, could transform the practical utility of molecular catalysts, simplify catalyst separation and recovery, and prevent catalyst decomposition by impeding bimolecular catalyst interactions. Previous strategies to heterogenize molecular catalysts via ligand-first binding to supports have suffered from reduced catalytic activity and leaching (loss) of catalyst, especially in environmentally friendly solvents like water. Herein, we describe an approach in which molecular catalysts are first attached to a metal oxide support through acidic ligands and then "encapsulated" with a metal oxide layer via atomic layer deposition (ALD) to prevent molecular detachment from the surface. For this initial report, which is based upon the well-studied Suzuki carbon-carbon cross-coupling reaction, we demonstrate the ability to achieve catalytic performance using a non-noble metal molecular catalyst in high aqueous content solvents. The catalyst chosen exhibits limited catalytic reactivity under homogeneous conditions due to extremely short catalyst lifetimes, but when heterogenized and immobilized with an optimal ALD layer thickness product yields >90% can be obtained in primarily aqueous solutions. Catalyst characterization before and after ALD application and catalytic reaction is achieved with infrared, electron paramagnetic resonance, and X-ray spectroscopies.