Centre d' Investigació en Nanociència i Nanotecnologia, Edifici CM-7, Campus UAB, Esfera UAB, E-08193 Bellaterra, Catalunya, Spain.
Phys Chem Chem Phys. 2011 Dec 28;13(48):21446-50. doi: 10.1039/c1cp22277e. Epub 2011 Nov 2.
The etching induced by water on hydrophobic (001) surfaces of enantiomeric L-, D- and racemic DL-valine crystals has been characterized by means of atomic force microscopy (AFM) at ambient conditions. Well-defined chiral parallelepipedic shallow patterns, one bilayer deep, are observed for the enantiomeric crystals with sides (steps) oriented along low index crystallographic directions. Hence, chirality can be readily identified by visual inspection of an AFM image after etching. The formation of such regular patterns can be rationalized using basic concepts of electrical dipolar interactions. The key factor that determines the relative etching rate for each step and thus defines the shape of the etching patterns is the orientation of the molecular dipoles with respect to the step edge. The simplicity of the approach allows the prediction of the effect of water etching on other amino acid crystals as well as the effect of the interaction of water with amino acid molecules forming part of more complex structures.
在环境条件下，通过原子力显微镜（AFM）对疏水性（001）表面的对映体 L-、D-和外消旋 DL-缬氨酸晶体的水蚀刻进行了表征。对于沿低指数晶向取向的各向异性晶体，可以观察到具有双原子层深度的明确定义的手性平行六面体浅图案。因此，通过在蚀刻后对 AFM 图像进行目视检查，可以轻松识别手性。使用电偶极相互作用的基本概念可以合理地解释这种规则图案的形成。决定每个步骤的相对蚀刻速率的关键因素，从而定义蚀刻图案的形状，是分子偶极相对于台阶边缘的取向。该方法的简单性允许预测水蚀刻对其他氨基酸晶体的影响，以及水与构成更复杂结构一部分的氨基酸分子相互作用的影响。
