Mian Mohammad Rasel, Wang Xijun, Wang Xingjie, Kirlikovali Kent O, Xie Haomiao, Ma Kaikai, Fahy Kira M, Chen Haoyuan, Islamoglu Timur, Snurr Randall Q, Farha Omar K
International Institute of Nanotechnology and Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
Department of Chemical & Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
J Am Chem Soc. 2023 Apr 5;145(13):7435-7445. doi: 10.1021/jacs.2c13887. Epub 2023 Mar 15.
Organophosphorus nerve agents are among the most toxic chemicals known and remain threats to humans due to their continued use despite international bans. Metal-organic frameworks (MOFs) have emerged as a class of heterogeneous catalysts with tunable structures that are capable of rapidly detoxifying these chemicals via hydrolysis at Lewis acidic active sites on the metal nodes. To date, the majority of studies in this field have focused on zirconium-based MOFs (Zr-MOFs) that contain hexanuclear Zr(IV) clusters, despite the large toolbox of Lewis acidic transition metal ions that are available to construct MOFs with similar catalytic properties. In particular, very few reports have disclosed the use of a Ti-based MOF (Ti-MOF) as a catalyst for this transformation even though Ti(IV) is a stronger Lewis acid than Zr(IV). In this work, we explored five Ti-MOFs (Ti-MFU-4l, NU-1012-NDC, MIL-125, Ti-MIL-101, MIL-177(LT), and MIL-177(HT)) that each contains Ti(IV) ions in unique coordination environments, including monometallic, bimetallic, octanuclear, triangular clusters, and extended chains, as catalysts to explore how both different node structures and different linkers (e.g., azolate and carboxylate) influence the binding and subsequent hydrolysis of an organophosphorus nerve agent simulant at Ti(IV)-based active sites in basic aqueous solutions. Experimental and theoretical studies confirm that Ti-MFU-4l, which contains monometallic Ti(IV)-OH species, exhibits the best catalytic performance among this series with a half-life of roughly 2 min. This places Ti-MFU-4l as one of the best nerve agent hydrolysis catalysts of any MOF reported to date.
有机磷神经毒剂是已知毒性最强的化学物质之一，尽管受到国际禁令限制仍在继续使用，对人类构成威胁。金属有机框架（MOF）已成为一类结构可调的多相催化剂，能够通过在金属节点上的路易斯酸性活性位点进行水解，快速将这些化学物质解毒。迄今为止，该领域的大多数研究都集中在含有六核Zr(IV)簇的锆基金属有机框架（Zr-MOF）上，尽管有大量可用于构建具有类似催化性能的金属有机框架的路易斯酸性过渡金属离子。特别是，尽管Ti(IV)是比Zr(IV)更强的路易斯酸，但很少有报道披露使用钛基金属有机框架（Ti-MOF）作为这种转化的催化剂。在这项工作中，我们探索了五种Ti-MOF（Ti-MFU-4l、NU-1012-NDC、MIL-125、Ti-MIL-101、MIL-177(LT)和MIL-177(HT)），它们各自在独特的配位环境中含有Ti(IV)离子，包括单金属、双金属、八核、三角形簇和延伸链，作为催化剂来研究不同的节点结构和不同的连接体（例如唑酸盐和羧酸盐）如何影响碱性水溶液中基于Ti(IV)的活性位点上有机磷神经毒剂模拟物的结合和随后的水解。实验和理论研究证实，含有单金属Ti(IV)-OH物种的Ti-MFU-4l在该系列中表现出最佳的催化性能，半衰期约为2分钟。这使Ti-MFU-4l成为迄今为止报道的任何金属有机框架中最好的神经毒剂水解催化剂之一。
