title: En route to surface-bound electric field-driven molecular motors.
abstract: Four caltrop-shaped molecules that might be useful as surface-bound electric field-driven molecular motors have been synthesized. The caltrops are comprised of a pair of electron donor-acceptor arms and a tripod base. The molecular arms are based on a carbazole or oligo(phenylene ethynylene) core with a strong net dipole. The tripod base uses a silicon atom as its core. The legs of the tripod bear sulfur-tipped bonding units, as acetyl-protected benzylic thiols, for bonding to a gold surface. The geometry of the tripod base allows the caltrop to project upward from a metallic surface after self-assembly. Ellipsometric studies show that self-assembled monolayers of the caltrops are formed on Au surfaces with molecular thicknesses consistent with the desired upright-shaft arrangement. As a result, the zwitterionic molecular arms might be controllable when electric fields are applied around the caltrops, thereby constituting field-driven motors.
authors.affiliation: Department of Chemistry, Rice University, 6100 South Main Street, Houston, Texas 77005, USA.
authors.forename: Huahua
authors.initials: H
authors.lastname: Jian
authors.forename: James M
authors.initials: JM
authors.lastname: Tour