Physisorption Controls the Conformation and Density of States of an Adsorbed Porphyrin
Physisorption Controls the Conformation and Density of States of an Adsorbed Porphyrin
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DOI：
10.1021/acs.jpcc.5b08350
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发表时间：
2015-12-17
影响因子：
3.7
通讯作者：
Moriarty, P.
中科院分区：
文献类型：
--
作者：
Jarvis, S. P.;Taylor, S.;Moriarty, P.
由吸附引起的构象变化可以显著地影响分子的性质。然而，尽管进行了广泛的研究，但支持构象转换的确切机制往往不清楚。在这里，我们表明，一个典型的灵活的分子，游离碱四（4-溴苯基）卟啉，吸附在Cu（111），构象严重依赖于其精确的吸附位点，并显着，大的构象变化是由分子和基板表面之间的货车范德华相互作用。结合扫描探针显微镜，单分子操作，密度泛函理论与分散密度泛函理论，和分子动力学模拟表明，货车德瓦尔斯力驱动显着扭曲的分子结构，使卟啉可以采取两个低能量构象之一。我们发现，吸附驱动的货车范德华力单独是能够引起大的位移的分子态密度，尽管明显没有化学相互作用。这些发现强调了货车范德华力在决定关键分子性质中的重要作用。
Conformational changes caused by adsorption can dramatically affect a molecules properties. Despite extensive study, however, the exact mechanisms underpinning conformational switching are often unclear. Here we show that the conformation of a prototypical flexible molecule, the free-base tetra(4-bromophenyl) porphyrin, adsorbed on Cu(111), depends critically on its precise adsorption site and that, remarkably, large conformational changes are dominated by van der Waals interactions between the molecule and the substrate surface. A combination of scanning probe microscopy, single-molecule manipulation, DFT with dispersion density functional theory, and molecular dynamics simulations show that van der Waals forces drive significant distortions of the molecular architecture so that the porphyrin can adopt one of two low-energy conformations. We find that adsorption driven by van der Waals forces alone is capable of causing large shifts in the molecular density of states, despite the apparent absence of chemical interactions. These findings highlight the essential role that van der Waals forces play in determining key molecular properties.