Chen Wanlin, Sanders Stephanie E, Özdamar Burak, Louaas Dorian, Brigiano Flavio Siro, Pezzotti Simone, Petersen Poul B, Gaigeot Marie-Pierre
Université Paris-Saclay, Université Evry, CNRS, LAMBE UMR8587, 91025Evry-Courcouronnes, France.
Department of Chemistry and Biochemistry, Ruhr University Bochum, 44801Bochum, Germany.
J Phys Chem Lett. 2023 Feb 9;14(5):1301-1309. doi: 10.1021/acs.jpclett.2c03300. Epub 2023 Feb 1.
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.
揭示非均相水界面处的微观亲水性和疏水性至关重要，因为它决定了诸如润湿性、双电层和反应活性等物理/化学性质。人们提出了几种分子和光谱描述符，但一个主要限制是它们之间缺乏联系。在这里，我们结合基于密度泛函理论的分子动力学模拟（DFT-MD）和和频振动光谱（SFG）来探索界面水与具有可调亲水性的自组装单分子层（SAM）接触时的响应。我们引入了一个微观指标来跟踪从疏水界面到亲水界面的转变。这个指标结合了H/V描述符，它是基于最顶层结合界面层（BIL）中水网络内优先取向的结构描述符，以及由BIL分辨的SFG光谱所携带的水的氢键合和悬空OH基团的光谱指纹。这个指标在亲水性/疏水性分子描述符和光谱测量量之间架起了一座桥梁，并提供了一种定量或定性解释实验SFG信号的方法。
