Fujii Shintaro, Shoji Yoshiaki, Masuda Yuma, Fukushima Takanori, Nishino Tomoaki
Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 W4-10 Ookayama, Meguro-ku, Tokyo 152-8551, Japan.
Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
J Phys Chem Lett. 2024 Nov 14;15(45):11189-11193. doi: 10.1021/acs.jpclett.4c02325. Epub 2024 Oct 31.
Despite the demand for nanoscale thermal management technologies of material surfaces and interfaces using organic molecules, heat transport properties at the single molecular level remain elusive due to the experimental difficulty of measuring temperature at the nanoscopic scale. Here we show how chemical bonding modes can affect the heat transport properties of single molecules. We focused on four molecular systems: benzylthiol linked to another phenyl group by either a triple (compound ), double (), or amide () bond and a common linear alkanethiol (), all of which are nearly identical in molecular length. We prepared binary self-assembled monolayers (SAMs) using as a common reference in combination with - and investigated their relative heat transport properties using scanning thermal microscopy (SThM). Two-dimensional temperature mapping of the binary SAMs showed that C≡C and C=C bonds provide more effective pathways for heat transport compared to C-C bonds. Since the amide molecule has resonance structures with C=N double bond character, we expected that its heat transport properties would be comparable to those of the thiols containing triple or double bonds. However, the heat transport properties of this molecule prevailed over the others, most likely due to the formation of additional heat transport pathways caused by intermolecular hydrogen bonding. These findings may provide important guidelines for the design of organic materials for nanoscale thermal management.
尽管对使用有机分子的材料表面和界面的纳米级热管理技术有需求，但由于在纳米尺度测量温度的实验困难，单分子水平的热传输特性仍然难以捉摸。在此，我们展示了化学键合模式如何影响单分子的热传输特性。我们聚焦于四个分子体系：通过三键（化合物 ）、双键（ ）或酰胺键（ ）与另一个苯基相连的苄硫醇，以及一种常见的直链烷硫醇（ ），所有这些分子在分子长度上几乎相同。我们以 作为共同参考，与 和 一起制备了二元自组装单分子层（SAMs），并使用扫描热显微镜（SThM）研究了它们的相对热传输特性。二元SAMs的二维温度映射表明，与C-C键相比，C≡C键和C=C键为热传输提供了更有效的途径。由于酰胺分子具有带有C=N双键特征的共振结构，我们预计其热传输特性将与含有三键或双键的硫醇相当。然而，该分子的热传输特性优于其他分子，最有可能是由于分子间氢键形成了额外的热传输途径。这些发现可能为纳米级热管理有机材料的设计提供重要指导。
