Ligand Effects on Charge Transport in Platinum(II) Acetylides
journal contributionposted on 25.02.2003, 00:00 by Terence L. Schull, James G. Kushmerick, Charles H. Patterson, Clifford George, Martin H. Moore, Steven K. Pollack, Ranganathan Shashidhar
To investigate the electrical characteristics of organometallic complexes as molecular conductors, organometallic π-conjugated molecules of the type trans-[PtL2(C⋮CC6H4SAc-4)2], where L = PCy3, PBu3, PPh3, P(OEt)3, P(OPh)3, were synthesized and characterized by NMR, IR, UV, and X-ray spectroscopies. For the three complexes (L = PCy3, PPh3, and P(OEt)3) that could be measured using a cross-wire junction technique, the current−voltage (I−V) characteristics of a molecular monolayer of these complexes showed no ligand effect, despite spectroscopic evidence that electronic interaction between the phosphine ligands and the π-system does occur. It was concluded that the tunneling efficiency across the molecule is the determining factor for conduction in this metal−molecule−metal system. It was also shown that the incorporation of a transition metal in π-conjugated molecular wires does not adversely affect charge transport compared to all-carbon π-conjugated molecular wires.