AI 中文总结
本文提出水上催化通过氢键和质子转移增强反应物间电荷转移稳定化，结合模拟与能量分解分析，揭示水合诱导的电荷转移响应是活化关键，连接传统水上化学与微滴反应。
AI 中文摘要
水上催化加速了水悬浮液中难溶有机底物之间的反应，但其分子起源仍存在争议。本文认为，氢键和质子转移都能增强有机反应物之间的电荷转移稳定化。表面水的氢键使反应复合物极化，而质子化则能在不需要相同反应路径的情况下更强烈地扰动同一供体-受体相互作用。我们将水/蒸气界面的模拟、有限温度环加成研究以及基于绝对局域分子轨道的能量分解分析联系起来。悬垂的OH基团建立反应性接触，但增加的过渡态氢键数量本身并不能解释活化。电子分析反而确定了水合增强的电荷转移稳定化，其增强幅度约为30%。对相关亲双烯体、质子化极限模型以及氧/硫取代的比较，将底物依赖的电子响应与水合和键形成联系起来。水合诱导的电荷转移响应指标提供了一个可检验的分子假说，而非催化加速的独立度量。活化取决于反应物和过渡态系综的差分稳定化。增加可及的反应界面可以放大这种局部机制，而无需特别强的额外电场，从而将传统水上化学与选定的微滴反应联系起来，同时区分吸附、浓度和内在分子活化。
英文摘要
On-water catalysis accelerates reactions between poorly soluble organic substrates in aqueous suspensions, but its molecular origin remains debated. This Account argues that hydrogen bonding and proton transfer can both enhance charge-transfer stabilization between the organic reactants. Hydrogen bonds from surface water polarize the reacting complex, whereas protonation can perturb the same donor-acceptor interaction more strongly without requiring identical reaction pathways. We connect simulations of the water/vapor interface, finite-temperature cycloaddition studies, and energy decomposition analysis based on absolutely localized molecular orbitals. Dangling OH groups establish reactive contacts, but an increased transition-state hydrogen-bond count alone does not explain activation. Electronic analysis instead identified hydration-enhanced charge-transfer stabilization between organic partners by approximately 30%. Comparisons of related dienophiles, a protonated limiting model, and oxygen/sulfur substitution link substrate-dependent electronic response to hydration and bond formation. A hydration-induced charge-transfer response metric provides a testable molecular hypothesis, not a standalone measure of catalytic acceleration. Activation depends on differential stabilization of reactant and transition-state ensembles. Increasing the accessible reactive interface can amplify this local mechanism without requiring exceptionally strong additional electric fields, connecting conventional on-water chemistry with selected microdroplet reactions while distinguishing adsorption, concentration, and intrinsic molecular activation.
Comments16 pages, 4 figures. Review article
