Geary Jackson, Wong Andy H, Xiao Dianne J
Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States.
J Am Chem Soc. 2021 Jul 14;143(27):10317-10323. doi: 10.1021/jacs.1c04030. Epub 2021 Jun 29.
While a number of approaches toward multicomponent metal-organic frameworks have been reported, new strategies affording greater structural versatility and molecular precision are needed to replicate the sophisticated active sites found in enzymes. Here, we outline a general method for templating functional groups within framework pores using thermolabile ligand cross-linkers. We show that tertiary ester-based cross-linkers can be used to install well-defined carboxylic acid pairs at precise relative distances and orientations. The tertiary ester linkages remain intact during framework formation but are readily cleaved to reveal free carboxylic acids upon microwave heating. Successful cross-linker synthesis, framework incorporation, and thermolysis is demonstrated using the mesoporous, terphenyl expanded analogues of MOF-74. When short cross-linkers are used, modeling studies show that the carboxylic acids are installed in a single configuration down the pore channels, spaced ∼7 Å apart. These precisely positioned acid pairs can be used as synthetic handles to build up more complex cooperative active sites.
虽然已经报道了多种制备多组分金属有机框架的方法，但仍需要新的策略来提供更大的结构多样性和分子精确性，以复制酶中发现的复杂活性位点。在此，我们概述了一种使用热不稳定配体交联剂在框架孔内模板化官能团的通用方法。我们表明，基于叔酯的交联剂可用于以精确的相对距离和取向安装定义明确的羧酸对。叔酯键在框架形成过程中保持完整，但在微波加热时很容易裂解以露出游离羧酸。使用MOF-74的介孔、三联苯扩展类似物证明了交联剂的成功合成、框架掺入和热解。当使用短交联剂时，建模研究表明羧酸以单一构型安装在孔道中，间距约为7埃。这些精确定位的酸对可用作合成手柄来构建更复杂的协同活性位点。
