title: Surface studies of aminoferrocene derivatives on gold: electrochemical sensors for chemical warfare agents.
abstract: The cystamine conjugate [(BocNH)Fc(CO)CSA]2 was prepared by coupling cystamine with the N-protected ferrocene amino acid derivative BocHN-Fc-COOH and was fully characterized by spectroscopic methods and by single-crystal X-ray diffraction. The cystamine conjugate forms films on gold substrates, which upon deprotection of the amino group, react with chemical warfare agent (CWA) mimics, upon which the redox properties of the Fc group are affected significantly. Cyclic voltammetry shows 50(5) mV anodic shifts of the Fc redox potentials after exposure to EtSCH2CH2Cl, a simulant for sulfur mustard HD (MA), and (NC)(EtO)2P(O), a simulant for nerve agent Tabun (NA). Exposure to MA and NA causes an increase in 2.3 and 4.5 ng mass, respectively, in QCM which indicates ca. 70% efficiency in Boc-deprotection. Ellipsometry measured a film thickness increase from 6(+/-1) A for the deprotected film to 10(+/-4) A for the film modified with MA and to 7(+/-2) A for the film modified with NA. AFM measurements show changes in the thickness and morphology of the film after reaction with MA and NA. The surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) and clearly show the attachment of the cystamine conjugate on the surface and its reaction with CWA mimics.
authors.affiliation: Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9.
authors.forename: Mohammad A K
authors.initials: MA
authors.lastname: Khan
authors.forename: Yi-Tao
authors.initials: YT
authors.lastname: Long
authors.forename: Gabriele
authors.initials: G
authors.lastname: Schatte
authors.forename: Heinz-Bernhard
authors.initials: HB
authors.lastname: Kraatz
mesh_terms: D002619:Chemical Warfare Agents / Q000032:analysis* / Q000138:chemical synthesis / Q000737:chemistry; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D004566:Electrodes; D005296:Ferrous Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D012680:Sensitivity and Specificity; D013053:Spectrophotometry; D013499:Surface Properties; D014965:X-Rays
chemical_list: D002619:Chemical Warfare Agents; D005296:Ferrous Compounds; D006046:Gold