Large Variations in the Single-Molecule Conductance of Cyclic and Bicyclic Silanes
Large Variations in the Single-Molecule Conductance of Cyclic and Bicyclic Silanes
复制标题
环状和双环硅烷的单分子电导的巨大变化。
DOI：
10.1021/jacs.8b10296
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发表时间：
2018-11-07
影响因子：
15
通讯作者：
Venkataraman, Latha
中科院分区：
文献类型：
--
作者：
Li, Haixing;Garner, Marc H.;Venkataraman, Latha
线性硅烷是有效的分子导线，由于强σ共轭的transoid构象，然而，结构功能关系的构象依赖性的硅烷的单分子电导仍然未经测试。在这里，我们报告的合成，电测量，和理论表征的四个系列的官能化的环状和双环硅烷，包括环四硅烷，环戊硅烷，双环[2.2.1]庚硅烷，和双环[2.2.2]辛硅烷，这都是由不同长度的线性硅连接子延长。我们发现一个不寻常的变化的单分子电导之间的四个系列在每个链接长度。我们确定的（双）环硅结构的相对电导，而不是比较在一个单一的长度通过使用的四个系列的共同长度依赖性。与环状α π共轭分子相比，σ共轭（双）环状硅烷的电导由通过分子的单一路径支配，并由沿着该路径的二面角沿着控制。
Linear silanes are efficient molecular wires due to strong sigma-conjugation in the transoid conformation; however, the structure-function relationship for the conformational dependence of the single-molecule conductance of silanes remains untested. Here we report the syntheses, electrical measurements, and theoretical characterization of four series of functionalized cyclic and bicyclic silanes including a cyclotetrasilane, a cyclopentasilane, a bicyclo[2.2.1]heptasilane, and a bicyclo[2.2.2]octasilane, which are all extended by linear silicon linkers of varying length. We find an unusual variation of the single-molecule conductance among the four series at each linker length. We determine the relative conductance of the (bi)cyclic silicon structures by using the common length dependence of the four series rather than comparing the conductance at a single length. In contrast with the cyclic a pi-conjugated molecules, the conductance of sigma-conjugated (bi)cyclic silanes is dominated by a single path through the molecule and is controlled by the dihedral angles along this path. This strong sensitivity to molecular conformation dictates the single-molecule conductance of sigma-conjugated silanes and allows for systematic control of the conductance through molecular design.