Nanomechanics of Anion−π Interaction in Aqueous Solution
Jiawen Zhang, Li Xiang, Bin Yan, Hongbo Zeng
Abstract
Noncovalent interactions play a constitutive role in numerous biological processes, including biomolecular adhesion, recognition, and transport. Unlike π–π and cation−π interactions, anion−π interaction was only recently and computationally recognized to participate in biomolecular science. Here, we present the first experimental identification and direct quantification of the nanomechanics of anion−π interaction in aqueous solution by using a surface forces apparatus with complementary computational simulations. Anionic phosphate ester and π-conjugated catecholic moieties that abound in marine bioadhesives were used as the model system. Robust adhesion was observed and attributed to anion−π interaction, which was found to be enabled by the cooperative cation−π interaction due to the coexistence of a cation. The anion−π interaction strength follows the trend phosphate ester > HPO42– > SO42– > NO3–, affected by charge density, polarity, and hydration effect.