<br>桨轮二钌炔基分子连接中外围取代基对主导传导轨道的控制,Chemical Science

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桨轮二钌炔基分子连接中外围取代基对主导传导轨道的控制
Chemical Science ( IF 7.6 ) Pub Date : 2021-07-08 , DOI: 10.1039/d1sc02407h
Shiori Ogawa _{1,

2} , Swarup Chattopadhyay ₃ , Yuya Tanaka _{1,

2} , Tatsuhiko Ohto ₄ , Tomofumi Tada ₅ , Hirokazu Tada ₄ , Shintaro Fujii ₆ , Tomoaki Nishino ₆ , Munetaka Akita _{1,

2}

Affiliation

控制通过分子结传输的电荷载流子对于热电材料至关重要。一般来说，电荷载流子取决于主要传导轨道，并且主要由末端锚定基团决定。本研究公开了具有二芳基甲脒支撑配体的叶轮二钌配合物1 ^R (DArF: p -RC ₆ H ₄ -NCHN-C ₆ H ₄ -R- p ) 的合成、溶液物理性质和单分子电导和两个轴向硫代茴香基乙炔基导电锚定基团，揭示了关于导电轨道的独特取代基效应。具有几个不同芳基取代基（R = OMe、H、Cl 和 CF ₃ ）的配合物1 ^R通过光谱和晶体学分析得到了充分表征。扫描隧道显微镜断裂结(STM-BJ)技术测定的单分子电导在10 ^-5至10 ^-4 G ₀范围内，电导顺序为1 ^OMe > 1 ^CF3 ≫ 1 ^H ∼ 1 ^Cl ，这与 R 的哈米特取代基常数σ不一致。循环伏安法揭示了源自二钌基序的1 ^R狭窄的 HOMO-LUMO 能隙，DFT 研究进一步支持了这一点。对这一独特结果的 DFT-NEGF 分析表明，主要电导路线从 HOMO 电导（对于1 ^OMe ）变为 LUMO 电导（对于1 ^CF3 ）。电导特性的巨大变化源于固有的窄 HOMO-LUMO 能隙。

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Control of dominant conduction orbitals by peripheral substituents in paddle-wheel diruthenium alkynyl molecular junctions

Control of charge carriers that transport through the molecular junctions is essential for thermoelectric materials. In general, the charge carrier depends on the dominant conduction orbitals and is dominantly determined by the terminal anchor groups. The present study discloses the synthesis, physical properties in solution, and single-molecule conductance of paddle-wheel diruthenium complexes 1^R having diarylformamidinato supporting ligands (DArF: p-R-C₆H₄-NCHN-C₆H₄-R-p) and two axial thioanisylethynyl conducting anchor groups, revealing unique substituent effects with respect to the conduction orbitals. The complexes 1^R with a few different aryl substituents (R = OMe, H, Cl, and CF₃) were fully characterized by spectroscopic and crystallographic analyses. The single-molecule conductance determined by the scanning tunneling microscope break junction (STM-BJ) technique was in the 10⁻⁵ to 10⁻⁴ G₀ region, and the order of conductance was 1^OMe > 1^CF3 ≫ 1^H ∼ 1^Cl, which was not consistent with the Hammett substituent constants σ of R. Cyclic voltammetry revealed the narrow HOMO–LUMO gaps of 1^R originating from the diruthenium motif, as further supported by the DFT study. The DFT-NEGF analysis of this unique result revealed that the dominant conductance routes changed from HOMO conductance (for 1^OMe) to LUMO conductance (for 1^CF3). The drastic change in the conductance properties originates from the intrinsic narrow HOMO–LUMO gaps.

更新日期：2021-07-20

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