title: Metal-organic frameworks post-synthetically modified with ferrocenyl groups: framework effects on redox processes and surface conduction.
abstract: Metal-organic framework (MOF) materials based on zinc(II) and aluminium(III) dicarboxylate frameworks with covalently attached ferrocene functional redox groups were synthesised by post-synthetic modification and investigated by voltammetry in aqueous and non-aqueous media. In the voltammetry experiments, ferrocene oxidation occurs in all cases, but chemically reversible and stable ferrocene oxidation without decay of the voltammetric response requires a "mild" dichloroethane solvent environment. The voltammetric response in this case is identified as "surface-confined" with fast surface-hopping of electrons and without affecting the bulk of MOF microcrystals. In aqueous media a more complex pH-dependent multi-stage redox process is observed associated with chemically irreversible bulk oxidation and disintegration of the MOF framework. A characteristic 30 mV per pH unit dependence of redox potentials is observed attributed to a "framework effect": the hydroxide-driven MOF framework dissolution.
authors.affiliation: Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Halls
authors.forename: Alberto
authors.initials: A
authors.lastname: Hernán-Gómez
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Burrows
authors.forename: Frank
authors.initials: F
authors.lastname: Marken