Conformations of cyclopentasilane stereoisomers control molecular junction conductance

TY - JOUR

T1 - Conformations of cyclopentasilane stereoisomers control molecular junction conductance

AU - Li, Haixing

AU - Garner, Marc Hamilton

AU - Shangguan, Zhichun

AU - Zheng, Qianwen

AU - Su, Timothy A.

AU - Neupane, Madhav

AU - Li, Panpan

AU - Velian, Alexandra

AU - Steigerwald, Michael L.

AU - Xiao, Shengxiong

AU - Nuckolls, Colin

AU - Solomon, Gemma C.

AU - Venkataraman, Latha

PY - 2016

Y1 - 2016

N2 - Here we examine the impact of ring conformation on the charge transport characteristics of cyclic pentasilane structures bound to gold electrodes in single molecule junctions. We investigate the conductance properties of alkylated cyclopentasilane cis and trans stereoisomers substituted in the 1,3-position with methylthiomethyl electrode binding groups using both the scanning tunneling microscope-based break junction technique and density functional theory based ab initio calculations. In contrast with the linear ones, these cyclic silanes yield lower conductance values; calculations reveal that the constrained dihedral geometries occurring within the ring are suboptimal for σ-orbital delocalization, and therefore, conductance. Theoretical calculations reproduce the measured conductance trends for both cis and trans isomers and find several distinct conformations that are likely to form stable molecular junctions at room temperature. Due to the weakened σ-conjugation in the molecule, through-space interactions are found to contribute significantly to the conductance. This manuscript details the vast conformational flexibility in cyclopentasilanes and the tremendous impact it has on controlling conductance.

AB - Here we examine the impact of ring conformation on the charge transport characteristics of cyclic pentasilane structures bound to gold electrodes in single molecule junctions. We investigate the conductance properties of alkylated cyclopentasilane cis and trans stereoisomers substituted in the 1,3-position with methylthiomethyl electrode binding groups using both the scanning tunneling microscope-based break junction technique and density functional theory based ab initio calculations. In contrast with the linear ones, these cyclic silanes yield lower conductance values; calculations reveal that the constrained dihedral geometries occurring within the ring are suboptimal for σ-orbital delocalization, and therefore, conductance. Theoretical calculations reproduce the measured conductance trends for both cis and trans isomers and find several distinct conformations that are likely to form stable molecular junctions at room temperature. Due to the weakened σ-conjugation in the molecule, through-space interactions are found to contribute significantly to the conductance. This manuscript details the vast conformational flexibility in cyclopentasilanes and the tremendous impact it has on controlling conductance.

U2 - 10.1039/c6sc01360k

DO - 10.1039/c6sc01360k

M3 - Journal article

AN - SCOPUS:84983591629

SN - 2041-6520

VL - 7

SP - 5657

EP - 5662

JO - Chemical Science

JF - Chemical Science

IS - 9

ER -