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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Solvent Polarity at Polar Solid Surfaces: The Role of Solvent Structure
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Solvent Polarity at Polar Solid Surfaces: The Role of Solvent Structure

机译：极性固体表面上的溶剂极性：溶剂结构的作用

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Resonance enhanced second harmonic spectra of the chromophore 4-aminobenzophenone (4ABP) were recorded at different solid/liquid interfaces. The solid substrates were hydrophilic silica and the solvents varied in size, shape and dielectric properties. Solvatochromic comparisons between SHG spectra of adsorbed 4ABP and excitation spectra of 4ABP in bulk solution reveal how solvent-substrate interactions and solvent structure alter interfacial solvent polarity from bulk solution limits. Not surprisingly, weakly associating systems consisting of polar substrates and nonpolar solvents are more polar than bulk solution, although there exist subtle, solvent-dependent differences in the strength of interfacial solvent-solute interactions. These differences are attributed to a solvent's ability to park against a rigid wall. Measurements of solute orientation at weakly associating interfaces supports a model in which the solute experiences multiple interactions with the substrate and adopts an orientation that is deflected significantly from the surface normal. Solvent polarity across strongly associating interfaces depends sensitively on solvent structure. Interfaces formed between hydrophilic silica substrates and n-alcohol solvents are significantly less polar than bulk solution, but branched alcohols create regions of enhanced local polarity. These effects are discussed in terms of the substrate's ability to induce long-range structure in the adjacent solvent through hydrogen-bonding interactions. Again, orientation measurements support the interfacial polarity results. In strongly associating systems, interfacial solutes adopt an orientation that is consistent with simulation predictions of alkyl chain tilt angles at extended solid surfaces.
机译：在不同的固/液界面处记录了发色团4-氨基二苯甲酮（4ABP）的共振增强的二次谐波谱。固体基质是亲水性二氧化硅，溶剂的大小，形状和介电性能各不相同。本体溶液中吸附的4ABP的SHG光谱和4ABP的激发光谱之间的溶剂变色比较揭示了溶剂-底物相互作用和溶剂结构如何改变本体溶液极限的界面溶剂极性。不足为奇的是，由极性底物和非极性溶剂组成的弱缔合体系比本体溶液更具极性，尽管在界面溶剂-溶质相互作用的强度方面存在细微的，取决于溶剂的差异。这些差异归因于溶剂在刚性壁上停车的能力。弱缔合界面上溶质取向的测量结果支持以下模型：溶质与基材发生多次相互作用，并采用与表面法线有明显偏离的取向。跨越强缔合界面的溶剂极性敏感地取决于溶剂结构。亲水性二氧化硅基质和正醇溶剂之间形成的界面的极性明显低于本体溶液，但支链醇会形成局部极性增强的区域。就底物通过氢键相互作用在相邻溶剂中诱导长程结构的能力进行了讨论。同样，方向测量结果支持界面极性结果。在强缔合体系中，界面溶质的取向与扩展的固体表面上烷基链倾斜角的模拟预测一致。

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