title: Modular "click" chemistry for electrochemically and photoelectrochemically active molecular interfaces to tin oxide surfaces.
abstract: We demonstrate the use of "click" chemistry to form electrochemically and photoelectrochemically active molecular interfaces to SnO(2) nanoparticle thin films. By using photochemical grafting to link a short-chain alcohol to the surface followed by conversion to a surface azide group, we enable use of the Cu(I)-catalyzed azide-alkyne [3 + 2] cycloaddition (CuAAC) reaction, a form of "click" chemistry, on metal oxide surfaces. Results are shown with three model compounds to test the surface chemistry and subsequent ability to achieve electrochemical and photoelectrochemical charge transfer. Surface-tethered ferrocene groups exhibit good electron-transfer characteristics with thermal rates estimated at >1000 s(-1). Time-resolved surface photovoltage measurements using a ruthenium terpyridyl coordination compound demonstrate photoelectron charge transfer on time scales of nanoseconds or less, limited by the laser pulse width. The results demonstrate that the CuAAC "click" reaction can be used to form electrochemically and photoelectrochemically active molecular interfaces to SnO(2) and other metal oxide semiconductors.
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue Madison, Wisconsin 53706, United States.
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Benson
authors.forename: Rose E
authors.initials: RE
authors.lastname: Ruther
authors.forename: James B
authors.initials: JB
authors.lastname: Gerken
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Rigsby
authors.forename: Lee M
authors.initials: LM
authors.lastname: Bishop
authors.forename: Yizheng
authors.initials: Y
authors.lastname: Tan
authors.forename: Shannon S
authors.initials: SS
authors.lastname: Stahl
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Hamers
mesh_terms: D002384:Catalysis; D057930:Click Chemistry; D056831:Coordination Complexes / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D055664:Electrochemical Techniques; D005296:Ferrous Compounds / Q000737:chemistry; D000075163:Metallocenes; D053758:Nanoparticles / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry; D012666:Semiconductors; D013499:Surface Properties; D017971:Tin Compounds / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D005296:Ferrous Compounds; D000075163:Metallocenes; D017971:Tin Compounds; D003300:Copper; D012428:Ruthenium; C045358:stannic oxide; C004998:ferrocene