Molecular Self-Assembly in a Poorly Screened Environment: F4TCNQ on Graphene/BN.
Molecular Self-Assembly in a Poorly Screened Environment: F4TCNQ on Graphene/BN.
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DOI：
10.1021/acsnano.5b05322
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发表时间：
2015-12-22
期刊：
影响因子：
17.1
通讯作者：
Crommie MF
中科院分区：
文献类型：
--
作者：
Tsai HZ;Omrani AA;Coh S;Oh H;Wickenburg S;Son YW;Wong D;Riss A;Jung HS;Nguyen GD;Rodgers GF;Aikawa AS;Taniguchi T;Watanabe K;Zettl A;Louie SG;Lu J;Cohen ML;Crommie MF
我们报告了一个扫描隧道显微镜和非接触原子力显微镜研究紧密堆积的2D岛的四氰基醌二甲烷（F4TCNQ）分子在表面的石墨烯层由氮化硼支持。虽然已知F4TCNQ分子形成粘性3D固体，但在3D中对F4TCNQ有吸引力的分子间相互作用在2D中是排斥的。因此，我们对石墨烯上F4TCNQ的内聚分子行为的实验观察是出乎意料的。这种自组装行为可以用一种新的固体形成机制来解释，这种机制发生在带电分子被放置在一个屏蔽不良的环境中时。当带负电荷的分子聚结时，局部功函数增加，导致电子流入聚结的分子岛并增加其内聚结合能。
We report a scanning tunneling microscopy and noncontact atomic force microscopy study of close-packed 2D islands of tetrafluorotetracyanoquinodimethane (F4TCNQ) molecules at the surface of a graphene layer supported by boron nitride. While F4TCNQ molecules are known to form cohesive 3D solids, the intermolecular interactions that are attractive for F4TCNQ in 3D are repulsive in 2D. Our experimental observation of cohesive molecular behavior for F4TCNQ on graphene is thus unexpected. This self-assembly behavior can be explained by a novel solid formation mechanism that occurs when charged molecules are placed in a poorly screened environment. As negatively charged molecules coalesce, the local work function increases, causing electrons to flow into the coalescing molecular island and increase its cohesive binding energy.