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Some Evidence for the Formation of an Azo Bond during the Electroreduction of Diazonium Salts on Au Substrates
Author(s) -
Ricci Alejandra M.,
Méndez De Leo Lucila P.,
Williams Federico J.,
Calvo Ernesto J.
Publication year - 2012
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201100882
Subject(s) - osmium , chemistry , cyclic voltammetry , x ray photoelectron spectroscopy , tetrafluoroborate , electrochemistry , photochemistry , infrared spectroscopy , electron transfer , surface modification , inorganic chemistry , bipyridine , redox , electrode , crystallography , organic chemistry , crystal structure , catalysis , ruthenium , ionic liquid , physics , nuclear magnetic resonance
Molecular films obtained by electrochemical reduction of diazoniuim tetrafluoroborate salts [4‐carboxybenzene (PhCOOH) and 4‐amino‐(2,3,5,6‐tetrafluoro)‐carboxybenzene (PhF 4 COOH)] on Au substrates and post‐functionalization with an osmium pyridil‐bipyridine complex are studied by a combination of X‐ray photoelectron (XPS) and polarization‐modulation infrared reflection absorption spectroscopy (PM‐IRRAS). The spectroscopic evidence suggests the formation of NN bonds tethering the complexes to Au. The surface coverage of the azo‐bonded osmium complexes strongly depends on the electrode potential. The resulting tethered osmium redox centres were characterized by cyclic voltammetry and impedance spectroscopy. Similar electron transfer‐rate constants were measured for both fluorinated and non fluorinated benzene‐linked Os complexes.