Tuning catalytic centers in heterogeneous catalyst, both in a chemical and a spatial manner, is a powerful approach to improve the stability and the efficiency of catalysts. While the chemical aspects are largely understood, the spatial interactions around active sites, comprised of non-covalent interactions, are difficult to maintain and challenging to study. Herein, the unique properties of covalent organic frameworks (COFs) are utilized to establish an ideal reaction environment for the hydrolysis of cellobiose and other common disaccharides in mild, metal-free, and neutral aqueous conditions. The chosen COF, HCl-PSA-IM-COF-OMe (“HCl” for hydrochloric acid, “PSA” for propyl sulfonic acid, “IM” for imidazole, and “OMe” for methoxy), is modified to be ultra-stable in aqueous conditions and possesses sulfonic acid groups for general acid catalysis and for enhanced hydrogen bonding with reactants as well as intraporous chloride anions for oxocarbenium intermediate stabilization. In addition, the system also relies on the differences in adsorptive binding behavior, K_ads, of the reactants and the products to the functionalized framework and benefits from a separate physical, kinetic process to boost the catalytic cycle. Due to its stability in aqueous conditions, HCl-PSA-IM-COF-OMe can be recycled and maintains its hydrolytic properties for five cycles before regeneration is needed.

中文翻译：

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模拟酶促非共价相互作用与功能化共价有机框架以改善纤维二糖的吸附和水解

以化学和空间方式调整多相催化剂中的催化中心是提高催化剂稳定性和效率的有效方法。虽然化学方面已广为人知，但活性位点周围的空间相互作用（包括非共价相互作用）难以维持且研究起来具有挑战性。在此，利用共价有机骨架 (COF) 的独特性质为纤维二糖和其他常见二糖在温和、无金属和中性水性条件下的水解建立了理想的反应环境。选择的 COF，HCl-PSA-IM-COF-OMe（“HCl”代表盐酸，“PSA”代表丙基磺酸，“IM”代表咪唑，“OMe”代表甲氧基），被改性为在水性条件下超稳定，并具有用于一般酸催化和增强与反应物的氢键结合的磺酸基团以及用于氧碳鎓中间体稳定的孔内氯离子。此外，该系统还依赖于吸附结合行为的差异，将反应_物和产物添加到功能化框架中，并受益于单独的物理、动力学过程以促进催化循环。由于其在水性条件下的稳定性，HCl-PSA-IM-COF-OMe 可以回收并在需要再生之前保持其水解性能五个循环。