Sum-Frequency Vibrational Spectroscopic Study of the Cation-π Interaction: Amine and Guanidine
Sokhuoy Sam1, Siheon Sung1, Sona Krem1
1Department of Physics, Sogang University, 35, Baekbeom-ro, Mapo-gu, Seoul 04107, Korea.
The Journal of Physical Chemistry. B
|September 27, 2022
Summary
This study reveals how cation-π interactions stabilize molecules like octadecylguanidine hydrochloride (ODG) and octadecylamine (ODA) with aromatic compounds. Indole showed stronger binding with ODG than phenol.
Area of Science:
- Physical Chemistry
- Biophysics
- Surface Science
Background:
- Cation-π interactions are crucial in biological processes and material science.
- Understanding these interactions at interfaces is key to controlling molecular behavior.
Purpose of the Study:
- To investigate the cation-π interactions between guanidine and amine headgroups with aromatic molecules.
- To explore how these interactions affect molecular stability and interfacial properties.
Main Methods:
- Sum-frequency vibrational spectroscopy (SFVS) was employed to study interfacial molecular behavior.
- Experiments involved octadecylguanidine hydrochloride (ODG) and octadecylamine (ODA) with phenol and indole in aqueous subphases.
Main Results:
- Aromatic molecules stabilized unstable octadecylguanidine hydrochloride (ODG) monolayers on water.
- Amine-π interactions in octadecylamine (ODA) promoted headgroup protonation and disordered the monolayer.
- Indole demonstrated stronger binding with ODG compared to phenol.
Conclusions:
- Cation-π interactions significantly influence the stability and structure of molecular monolayers at the water interface.
- The nature of both the cation and the aromatic molecule affects binding strength and interfacial organization.
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