title: Gating of Quantum Interference in Molecular Junctions by Heteroatom Substitution.
abstract: To guide the choice of future synthetic targets for single-molecule electronics, qualitative design rules are needed, which describe the effect of modifying chemical structure. Here the effect of heteroatom substitution on destructive quantum interference (QI) in single-molecule junctions is, for the first time experimentally addressed by investigating the conductance change when a "parent" meta-phenylene ethylene-type oligomer (m-OPE) is modified to yield a "daughter" by inserting one nitrogen atom into the m-OPE core. We find that if the substituted nitrogen is in a meta position relative to both acetylene linkers, the daughter conductance remains as low as the parent. However, if the substituted nitrogen is in an ortho position relative to one acetylene linker and a para position relative to the other, destructive QI is alleviated and the daughter conductance is high. This behavior contrasts with that of a para-connected parent, whose conductance is unaffected by heteroatom substitution. These experimental findings are rationalized by transport calculations and also agree with recent "magic ratio rules", which capture the role of connectivity in determining the electrical conductance of such parents and daughters.
authors.affiliation: Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland.
authors.forename: Xunshan
authors.initials: X
authors.lastname: Liu
authors.affiliation: Quantum Technology Centre, Physics Department, Lancaster University, Lancaster, LA1 4YB, UK.
authors.forename: Sara
authors.initials: S
authors.lastname: Sangtarash
authors.affiliation: Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland.
authors.forename: David
authors.initials: D
authors.lastname: Reber
authors.affiliation: Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Quantum Technology Centre, Physics Department, Lancaster University, Lancaster, LA1 4YB, UK.
authors.forename: Hatef
authors.initials: H
authors.lastname: Sadeghi
authors.affiliation: Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Shi
authors.affiliation: Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
authors.forename: Zong-Yuan
authors.initials: ZY
authors.lastname: Xiao
authors.affiliation: Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Hong
authors.affiliation: Quantum Technology Centre, Physics Department, Lancaster University, Lancaster, LA1 4YB, UK.
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Lambert
authors.affiliation: Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland.
authors.forename: Shi-Xia
authors.identifier: 0000-0001-6104-4320
authors.initials: SX
authors.lastname: Liu
keywords: density functional calculations; heteroatom effects; molecular electronics; quantum interference; single-molecule transport