Single-molecule force spectroscopy reveals cation-π interactions in aqueous media are highly affected by cation dehydration

Cation-π interactions underlie many important processes in biology and materials science. However, experimental investigations of cation-π interactions in aqueous media remain challenging. Here, we studied the cation-π binding strength and mechanism by pulling two hydrophobic polymers with distinct...

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Main Authors: Di, Weishuai, Xue, Kai, Cai, Jun, Zhu, Zhenshu, Li, Zihan, Fu, Hui, Lei, Hai, Hu, Wenbing, Tang, Chun, Wang, Wei, Cao, Yi
Other Authors: School of Physical and Mathematical Sciences
Format: Article
Language:English
Published: 2023
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Online Access:https://hdl.handle.net/10356/169314
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Institution: Nanyang Technological University
Language: English
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Summary:Cation-π interactions underlie many important processes in biology and materials science. However, experimental investigations of cation-π interactions in aqueous media remain challenging. Here, we studied the cation-π binding strength and mechanism by pulling two hydrophobic polymers with distinct cation binding properties, i.e., poly-pentafluorostyrene and polystyrene, in aqueous media using single-molecule force spectroscopy and nuclear magnetic resonance measurement. We found that the interaction strengths linearly depend on the cation concentrations, following the order of Li^{+}<NH_{4}^{+}<Na^{+}<K^{+}. The binding energies are 0.03-0.23  kJ mol^{-1} M^{-1}. This order is distinct from the strength of cation-π interactions in gas phase and may be caused by the different dehydration ability of the cations. Taken together, our method provides a unique perspective to investigate cation-π interactions under physiologically relevant conditions.