Measuring the mechanical properties of molecular conformers.
Measuring the mechanical properties of molecular conformers.
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DOI：
10.1038/ncomms9338
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发表时间：
2015-09-21
影响因子：
16.6
通讯作者：
Moriarty P
中科院分区：
文献类型：
--
作者：
Jarvis SP;Taylor S;Baran JD;Champness NR;Larsson JA;Moriarty P
扫描探针驱动的单分子操作已被证明是一个非常强大的工具，系统的原子尺度的分子吸附质的审讯。然而，到目前为止，分子构象对推动或拉动单个分子所需的力的影响程度还没有被探索。在这里，我们探测两个四（4-溴苯基）卟啉构象的机械化学反应，使用非接触式原子力显微镜，我们发现一个很大的差异所需的横向力操纵。值得注意的是，尽管共享非常相似的吸附特性，势能表面的变化能够禁止探针诱导的定位的一个构象，同时允许操纵的替代构象形式。我们的研究结果进行解释的背景下，分散校正的密度泛函理论计算，揭示显着差异的扩散障碍，每个构象。这些结果表明，构象变化显着修改的机械响应，甚至简单的卟啉，可能会影响许多其他灵活的分子。 单分子的操作可以使用扫描探针显微镜实现，但分子构象对这一过程的影响，到目前为止，还不清楚。在这里，作者探测了表面上两种不同类型的卟啉构象，并发现它们的机械化学反应存在很大差异。
Scanning probe-actuated single molecule manipulation has proven to be an exceptionally powerful tool for the systematic atomic-scale interrogation of molecular adsorbates. To date, however, the extent to which molecular conformation affects the force required to push or pull a single molecule has not been explored. Here we probe the mechanochemical response of two tetra(4-bromophenyl)porphyrin conformers using non-contact atomic force microscopy where we find a large difference between the lateral forces required for manipulation. Remarkably, despite sharing very similar adsorption characteristics, variations in the potential energy surface are capable of prohibiting probe-induced positioning of one conformer, while simultaneously permitting manipulation of the alternative conformational form. Our results are interpreted in the context of dispersion-corrected density functional theory calculations which reveal significant differences in the diffusion barriers for each conformer. These results demonstrate that conformational variation significantly modifies the mechanical response of even simple porpyhrins, potentially affecting many other flexible molecules. Manipulation of single molecules can be achieved using scanning probe microscopy but the influence of molecular conformation on this process has, until now, been unclear. Here, the authors probe two different types of porphyrin conformer on a surface and see strong differences in their mechanochemical response.