J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic.
Institute of Nanotechnology, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe, Germany.
Molecules. 2022 Nov 29;27(23):8320. doi: 10.3390/molecules27238320.
Self-assembled monolayers (SAMs) of terpyridine-based transition metal (ruthenium and osmium) complexes, anchored to gold substrate via tripodal anchoring groups, have been investigated as possible redox switching elements for molecular electronics. An electrochemical study was complemented by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) methods. STM was used for determination of the SAM conductance values, and computation of the attenuation factor β from tunneling current-distance curves. We have shown that SAMs of molecules contain larger adlayer structures compared with SAMs of molecules, which are characterized by a large number of almost evenly distributed small islands. Furthermore, upon cyclic voltammetric experimentation, films rearrange to form a smaller number of even larger islands, reminiscent of the Ostwald ripening process. SAMs displayed a higher surface concentration of molecules and lower conductance compared with SAMs. The attenuation factor of films changed dramatically, upon electrochemical cycling, to a higher value. These observations are in accordance with previously reported electron transfer kinetics studies.
基于三齿配体的金属（钌和锇）配合物的自组装单分子层（SAMs）通过三脚架锚固基团固定在金基底上，已被研究作为分子电子学中可能的氧化还原开关元件。电化学研究得到原子力显微镜（AFM）和扫描隧道显微镜（STM）方法的补充。STM 用于确定 SAM 的电导值，并从隧道电流-距离曲线计算衰减因子β。我们已经表明，与 分子的 SAM 相比，分子的 SAM 包含更大的吸附层结构，其特征是存在大量几乎均匀分布的小岛。此外，在循环伏安实验中，薄膜重新排列形成数量更少但更大的岛，类似于奥斯特瓦尔德熟化过程。SAMs 显示出比 SAMs 更高的分子表面浓度和更低的电导率。衰减因子的薄膜在电化学循环过程中急剧变化，达到更高的值。这些观察结果与先前报道的电子转移动力学研究一致。
