Centre d'Investigació en Nanociència i Nanotecnologia, CIN2 (CSIC-ICN), Edifici CM7, Esfera UAB, Campus de Bellaterra, E-08193 Barcelona, Spain.
J Am Chem Soc. 2009 Dec 16;131(49):17853-9. doi: 10.1021/ja905961h.
The amphiphillic character, that is, the capacity to simultaneously attract and repel water, has been traditionally reserved to organic molecules such as phospholipids and surfactants, containing both hydrophilic and hydrophobic groups within the same molecule. However, this general concept can be extended to artificial structures such as micrometer-sized particles, the so-called Janus particles, and patterned surfaces. Here we provide an example of an amphiphillic crystalline solid, l-alanine, by combining atomic force microscopy measurements performed on two different cleavage surfaces showing contrasting behaviors when exposed to water vapor, with computer simulations that allow us to clarify the dipolar origin of this behavior. Although we take l-alanine as an example, our results should apply quite generally to dipolar molecular crystals.
两亲性特征，即同时吸引和排斥水的能力，传统上仅保留给有机分子，如同时含有亲水和疏水基团的磷脂和表面活性剂。然而，这个普遍的概念可以扩展到人工结构，如微米级颗粒，所谓的“Janus 颗粒”和图案化表面。在这里，我们通过结合在两个不同的解理表面上进行的原子力显微镜测量，为两亲性晶态固体 l-丙氨酸提供了一个实例，这两个表面在暴露于水蒸气时表现出相反的行为，同时进行的计算机模拟使我们能够阐明这种行为的偶极子起源。尽管我们以 l-丙氨酸为例，但我们的结果应该相当普遍地适用于偶极分子晶体。
