On the Trail of Molecular Hydrophilicity and Hydrophobicity at Aqueous Interfaces
Journal of Physical Chemistry Letters, vol.14, no.5, pp.1301-1309, 2023 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 14 Issue: 5
- Publication Date: 2023
- Doi Number: 10.1021/acs.jpclett.2c03300
- Journal Name: Journal of Physical Chemistry Letters
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, MEDLINE, Nature Index
- Page Numbers: pp.1301-1309
- TED University Affiliated: No
Abstract
Uncovering microscopic hydrophilicity and hydrophobicity at heterogeneous aqueous interfaces is essential as it dictates physico/chemical properties such as wetting, the electrical double layer, and reactivity. Several molecular and spectroscopic descriptors were proposed, but a major limitation is the lack of connections between them. Here, we combine density functional theory-based MD simulations (DFT-MD) and SFG spectroscopy to explore how interfacial water responds in contact with self-assembled monolayers (SAM) of tunable hydrophilicity. We introduce a microscopic metric to track the transition from hydrophobic to hydrophilic interfaces. This metric combines the H/V descriptor, a structural descriptor based on the preferential orientation within the water network in the topmost binding interfacial layer (BIL) and spectroscopic fingerprints of H-bonded and dangling OH groups of water carried by BIL-resolved SFG spectra. This metric builds a bridge between molecular descriptors of hydrophilicity/hydrophobicity and spectroscopically measured quantities and provides a recipe to quantitatively or qualitatively interpret experimental SFG signals.