Cytosine monohydrate under mechanical stress
Cytosine monohydrate under mechanical stress
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DOI：
10.1039/d3ce00293d
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发表时间：
2023-04-28
期刊：
影响因子：
3.1
通讯作者：
Swift, Jennifer A.
中科院分区：
文献类型：
--
作者：
Fleming, Megan E.;Hooks, Daniel E.;Swift, Jennifer A.
在一水胞嘧啶（CM）的（100）表面上用圆锥形尖端进行纳米压痕，显示出在负载范围内的高度各向异性响应。由于表面的前手性结构，缩进后原子力显微镜图像确定了不对称变形响应。低粗糙度滑移面的激活引起π -堆的运动，而不是它们沿一维氢键带方向的位移。各向异性的产生是因为滑移只能传播到压痕的一侧，因为尖端本身在首选平面上提供了滑移障碍，从而迫使二次滑移系统的激活和堆积。这种各向异性变形与先前的工作有关，该工作提出了一个带状旋转模型来解释CM与其脱水产物之间的拓扑转换。CM所表现出的纳米力学性能的不对称性为转动模型提供了进一步的支持，也强调了水合物力学性能与其固态脱水机制之间的内在关系。
Nanoindentation performed with a conospherical tip on the (100) face of cytosine monohydrate (CM) revealed a highly anisotropic response over a range of loads. Post-indent atomic force microscopy images identified an asymmetric deformation response owing to the pro-chiral structure of the surface. Activation of low rugosity slip planes induces movement of pi-stacks rather than their displacement along the 1-dimensional hydrogen bonded ribbon direction. Anisotropy arises because slip can only propagate to one side of the indent, as the tip itself imparts a barrier to slip on the preferred plane thereby forcing the activation of secondary slip systems and pileup. The anisotropic deformation is of interest in relation to previous work which proposed a ribbon-rotation model to account for the topotactic conversion between CM and the product of its dehydration. The asymmetry in the nanomechanical properties exhibited by CM provides further support for the rotational model put forth and also serves to underscore the inherent relationship between a hydrate's mechanical properties and its solid state dehydration mechanism.