TY - JOUR
T1 - Large Variations in the Single-Molecule Conductance of Cyclic and Bicyclic Silanes
AU - Li, Haixing
AU - Garner, Marc H.
AU - Shangguan, Zhichun
AU - Chen, Yan
AU - Zheng, Qianwen
AU - Su, Timothy A.
AU - Neupane, Madhav
AU - Liu, Taifeng
AU - Steigerwald, Michael L.
AU - Ng, Fay
AU - Nuckolls, Colin
AU - Xiao, Shengxiong
AU - Solomon, Gemma C.
AU - Venkataraman, Latha
PY - 2018/11/7
Y1 - 2018/11/7
N2 - Linear silanes are efficient molecular wires due to strong σ-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 π-conjugated molecules, the conductance of σ-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 σ-conjugated silanes and allows for systematic control of the conductance through molecular design.
AB - Linear silanes are efficient molecular wires due to strong σ-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 π-conjugated molecules, the conductance of σ-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 σ-conjugated silanes and allows for systematic control of the conductance through molecular design.
U2 - 10.1021/jacs.8b10296
DO - 10.1021/jacs.8b10296
M3 - Journal article
C2 - 30372051
SN - 0002-7863
VL - 140
SP - 15080
EP - 15088
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 44
ER -