title: Design and synthesis of ferrocene probe molecules for detection by electrochemical methods.
abstract: A series of ferrocenyl conjugates to fatty acids have been designed and synthesized to establish the key properties required for use in biomolecular binding studies. Amperometric detection of the ferrocene conjugates was sought in the region of 0.3 V (vs Ag/AgCl) for use in protein/blood solutions. Different linkers and solubilizing moieties were incorporated to produce a conjugate with optimal electrochemical properties. In electrochemical studies, the linker directly attached to the ferrocene was found to affect significantly the E(1/2) value and the stability of the ferrocenium cation. Ester-linked ferrocene conjugates had E(1/2) ranging from +400 to +410 mV, while amide-linked compounds ranged from +350 to +370 mV and the amines +260 to +270 mV. Folding of long-chain substituents around the ferrocene, also significantly affected by the choice of linker, was inferred as a secondary effect that increased E(1/2). The stability of the ferrocenium cation decreased systematically as E(1/2) increased. Disubstituted ferrocene ester and amide conjugates, with oxidation potentials of +640 and +570 mV, respectively, showed only a barely discernible reduction wave in cyclic voltammetry at 50 mV/s. Electrochemical measurements identified two lead compounds with the common structural characteristics of an amide and carbamate linker (compounds 17 and 21) with a C(11) fatty acid chain attached. It is envisaged that such molecules can be used to mimic and study the biomolecular binding interaction between fatty acids and molecules such as human serum albumin.
authors.affiliation: Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Tranchant
authors.forename: Anne-Cécile
authors.initials: AC
authors.lastname: Hervé
authors.forename: Stephen
authors.initials: S
authors.lastname: Carlisle
authors.forename: Phillip
authors.initials: P
authors.lastname: Lowe
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Slevin
authors.forename: Camilla
authors.initials: C
authors.lastname: Forssten
authors.forename: John
authors.initials: J
authors.lastname: Dilleen
authors.forename: Rajiv
authors.initials: R
authors.lastname: Bhalla
authors.forename: David E
authors.initials: DE
authors.lastname: Williams
authors.forename: Alethea B
authors.initials: AB
authors.lastname: Tabor
authors.forename: Helen C
authors.initials: HC
authors.lastname: Hailes
mesh_terms: D004563:Electrochemistry / Q000379:methods*; D005296:Ferrous Compounds / Q000737:chemistry*; D006801:Humans; D000075163:Metallocenes; D015335:Molecular Probes / Q000138:chemical synthesis / Q000737:chemistry; D015394:Molecular Structure; D011092:Polyethylene Glycols / Q000737:chemistry
chemical_list: D005296:Ferrous Compounds; D000075163:Metallocenes; D015335:Molecular Probes; D011092:Polyethylene Glycols; C004998:ferrocene