title: Non-covalent assembly of a photoswitchable surface.
abstract: A noncovalently bound multilayered thin film in which individual layers are linked by metal ligand interactions undergoes a photochemically initiated permanent change in surface wettability. The film consists of three separate layers: a SAM on gold of 4-[(10-mercaptodecyl)oxy]pyridine-2,6-dicarboxylic acid, a layer of Cu(II) ions that are deposited onto the SAM and bind symmetrically in the site provided by the two carboxylate groups and the pyridyl nitrogen atom, and a layer of cis-2,2'-dipyridylethylene, which caps the Cu(II) layer by complexation through both pyridyl nitrogen atoms (Film I). Photoexcitation of the film in chloroform at 300 nm leads to substantial cis-trans isomerization as indicated by conductivity, impedance, grazing incidence IR, and contact angle measurements. The latter show a decrease in contact angle (increase in wettability) of 17 degrees , which is attributed to exposure of both the underlying Cu(II) layer and one of the pyridyl ring nitrogen atoms following isomerization to the trans isomer.
authors.affiliation: Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA.
authors.forename: Christopher G F
authors.initials: CG
authors.lastname: Cooper
authors.forename: John C
authors.initials: JC
authors.lastname: MacDonald
authors.forename: Ernesto
authors.initials: E
authors.lastname: Soto
authors.forename: W Grant
authors.initials: WG
authors.lastname: McGimpsey