Molecular Self-Assembly Versus Surface Restructuring During Calcite Dissolution.
Molecular Self-Assembly Versus Surface Restructuring During Calcite Dissolution.
复制标题
DOI：
10.1021/acs.langmuir.6b02685
复制
发表时间：
2016-09
期刊：
影响因子：
--
通讯作者：
M. Nalbach;S. Klassen;R. Bechstein;A. Kühnle
中科院分区：
文献类型：
--
作者：
M. Nalbach;S. Klassen;R. Bechstein;A. Kühnle
已知有机添加剂以各种方式改变矿物-水界面。一方面，有机分子可以自组装成润湿表面的有序结构。另一方面，它们的存在会影响界面形态，称为表面重构。在这里，我们研究了一类钙络合偶氮染料对方解石（10.4）溶解的影响，使用高分辨率原子力显微镜在水溶液中操作，重点是两个宪法异构体铬黑T和铬黑A。一个非常明显的表面重组中观察到的染料溶液的存在下，无论使用的具体染料和独立的pH值。这种表面重组是通过稳定的非极性急性和极性[010]步骤的边缘，导致在一个大大改变，特征界面形态。形成鲜明对比的流行的表面重组，一个有序的分子结构上的晶体阶地观察到只有在非常特定的条件下。这种有序条纹状分子结构的形成仅由铬黑A获得，并且限于pH值约3.6的非常窄的pH窗口。我们的研究结果表明，这种分子自组装需要一个相当精确的调整分子的性质，包括构象和去质子化状态的控制。这与添加剂诱导的表面重构形成鲜明对比，添加剂诱导的表面重构似乎对pH变化和分子构象的变化都更加稳健。
Organic additives are known to alter the mineral-water interface in various ways. On the one hand, organic molecules can self-assemble into ordered structures wetting the surface. On the other hand, their presence can affect the interfacial morphology, referred to as surface restructuring. Here, we investigate the impact of a class of calcium-complexing azo dyes on the dissolution of calcite (10.4) using high-resolution atomic force microscopy operated in aqueous solution, with a focus on the two constitutional isomers Eriochrome Black T and Eriochrome Black A. A very pronounced surface restructuring is observed in the presence of the dye solution, irrespective of the specific dye used and independent of the pH. This surface restructuring is obtained by the stabilization of both the nonpolar acute and the polar [010] step edges, resulting in a greatly altered, characteristic interface morphology. In sharp contrast to the prevalence of the surface restructuring, an ordered molecular structure on the crystal terraces is observed only under very specific conditions. This formation of an ordered stripe-like molecular structure is obtained from Eriochrome Black A only and limited to a very narrow pH window at a pH value of around 3.6. Our results indicate that such molecular self-assembly requires a rather precise adjustment of the molecular properties including control of the conformation and deprotonation state. This is in sharp contrast to the additive-induced surface restructuring, which appears to be far more robust against both pH changes and variations in the molecular conformation.