Liu Hao, Scott Harrison M, Lin Binzhou, Huang Xiaolong, Smith Mark D, Shimizu Ken D
Department of Chemistry and Biochemistry, University of South Carolina Columbia SC 29208 USA
Chem Sci. 2025 Aug 28. doi: 10.1039/d5sc02852c.
Solvent attenuation of dispersion interactions was quantified using a new class of rigid intramolecular CH-π molecular balances. These balances incorporate small, two-carbon CH donors that minimize solvophobic effects and isolate the dispersion component. Folding energies (Δ ) were measured across eight solvents: cyclohexane, toluene, chloroform, ethyl acetate, acetone, acetonitrile, DMSO, and methanol. Attenuation values in nonpolar solvents closely matched those reported by Peter Chen using a bimolecular host-guest system. Our use of a molecular balance also enabled study in polar solvents where the attenuation remained similarly high in polar solvents such as DMSO and methanol. The narrow 75 to 80 percent range observed across all solvents demonstrates the consistency of dispersion attenuation and the effectiveness of molecular balances in quantifying weak noncovalent forces while avoiding interference from solvent driven effects. Comparisons between sp and sp CH donors showed similar dispersion contributions, with sp groups exhibiting stronger overall interactions due to greater electrostatic stabilization. As a result, sp CH groups formed stronger interactions in nonpolar solvents, while both CH types showed similar strengths in polar solvents.
使用一类新型的刚性分子内CH-π分子平衡来量化色散相互作用的溶剂衰减。这些平衡包含小的二碳CH供体，可将疏溶剂效应降至最低并分离出色散成分。在八种溶剂中测量了折叠能（Δ）：环己烷、甲苯、氯仿、乙酸乙酯、丙酮、乙腈、二甲基亚砜（DMSO）和甲醇。非极性溶剂中的衰减值与Peter Chen使用双分子主客体系统报告的值密切匹配。我们使用分子平衡还能够在极性溶剂中进行研究，在DMSO和甲醇等极性溶剂中衰减同样很高。在所有溶剂中观察到的75%至80%的狭窄范围表明了色散衰减的一致性以及分子平衡在量化弱非共价力同时避免溶剂驱动效应干扰方面的有效性。sp和sp CH供体之间的比较显示出色散贡献相似，由于更强的静电稳定作用，sp基团表现出更强的整体相互作用。因此，sp CH基团在非极性溶剂中形成更强的相互作用，而两种CH类型在极性溶剂中表现出相似的强度。
