National Engineering Laboratory for Clean Technology of Leather Manufacture, College of Biomass Science and Engineering, Sichuan University, Chengdu, 610065, China.
Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada.
J Colloid Interface Sci. 2022 Jun;615:778-785. doi: 10.1016/j.jcis.2022.01.184. Epub 2022 Feb 7.
Despite the much progress in developing π-conjugated fluoroarene moieties based functional materials in which anion - π interactions are commonly involved, it remains challenging to quantitatively characterize the nanomechanical interaction mechanism of these anion - π systems, particularly in aqueous solutions. In this study, we reported the first experimental quantification of the nanomechanics of anion - π interactions between π-conjugated fluoroarene moieties and carboxylate anions in aqueous solutions through direct molecular force measurements, with a special focus on the impact of the anion species, concentration and of the substitution effect of aromatic side group. The results using surface forces apparatus (SFA) and single-molecule force spectroscopy (SMFS) provide complementary evidences to demonstrate that the robust and reversible adhesion measured between the fluoroarene π systems and carboxylate anions was mainly attributed to anion - π interaction. Moreover, their nanomechanical properties were also systematically scrutinized, with the interaction strength being found to be significantly determined by the contact time, the type of fluoroarene systems (PFST > DFST) and the type of anions and ion concentration (HPO > CO > I > Cl ≈ NO > F).
尽管在开发基于π-共轭氟芳基部分的功能材料方面取得了很大进展，其中通常涉及阴离子-π相互作用，但定量表征这些阴离子-π系统的纳米力学相互作用机制仍然具有挑战性，特别是在水溶液中。在这项研究中，我们通过直接分子力测量首次报道了在水溶液中π-共轭氟芳基部分和羧酸盐阴离子之间阴离子-π相互作用的纳米力学的实验定量，特别关注阴离子种类、浓度和芳基侧基取代效应的影响。使用表面力仪 (SFA) 和单分子力谱 (SMFS) 的结果提供了互补的证据，证明在氟芳基π系统和羧酸盐阴离子之间测量到的强大且可逆的粘附主要归因于阴离子-π相互作用。此外，还系统地研究了它们的纳米力学性质，发现相互作用强度明显取决于接触时间、氟芳基系统的类型 (PFST>DFST) 以及阴离子和离子浓度的类型 (HPO>CO>I>Cl≈NO>F)。
