title: Synthesis and electrical characterization of oligo(phenylene ethynylene) molecular wires coordinated to transition metal complexes.
abstract: Organometallic wires are interesting alternatives to conventional molecular wires based on a pure organic system because of the presence of d orbitals in the transition metal complex. However, synthetic problems, such as decreased stability of the compounds when labile metal complexes are present, often impede their isolation in a pure state and preclude a rapid development of such hybrid molecular wires. In this work, we show that preassembled self-assembled monolayers (SAM) based on pyridine-terminated 1-((4-acetylthiophenyl)ethynyl)-4-((4-pyridyl)ethynyl)benzene can act as a template for the architectural build up of a second layer of transition metal complexes to form an array of organometallic molecular wires on gold. Ru(II)(terpy)(bipy)(2+) (terpy = 2,2':6',2''-terpyridine and bipy = 2,2'-bipyridine) or cyclometalated Pt(II)(pbipy) (pbipy = 6-phenyl-2,2'-bipyridine) were axially coordinated onto the organic SAM via its terminal pyridinium moieties. Current-voltage studies show that the electronic coupling between the transition metal and organic wire produces a molecular wire that exhibits higher conductance than the original organic chain. The presence of the transition metal complexes in the hybrid molecular wire introduces distinctive negative differential resistance (NDR) effects.
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Zhaoyue
authors.initials: Z
authors.lastname: Ng
authors.forename: Kian Ping
authors.initials: KP
authors.lastname: Loh
authors.forename: Liqian
authors.initials: L
authors.lastname: Li
authors.forename: Peter
authors.initials: P
authors.lastname: Ho
authors.forename: Ping
authors.initials: P
authors.lastname: Bai
authors.forename: John H K
authors.initials: JH
authors.lastname: Yip