title: Direct Measurement of Electron Transfer in Nanoscale Host-Guest Systems: Metallocenes in Carbon Nanotubes.
abstract: Electron-transfer processes play a significant role in host-guest interactions and determine physicochemical phenomena emerging at the nanoscale that can be harnessed in electronic or optical devices, as well as biochemical and catalytic systems. A novel method for qualifying and quantifying the electronic doping of single walled carbon nanotubes (SWNTs) using electrochemistry has been developed that establishes a direct link between these experimental measurements and ab initio DFT calculations. Metallocenes such as cobaltocene and methylated ferrocene derivatives were encapsulated inside SWNTs (1.4 nm diameter) and cyclic voltammetry (CV) was performed on the resultant host-guest systems. The electron transfer between the guest molecules and the host SWNTs is measured as a function of shift in the redox potential (E1/2 ) of Co(II) /Co(I) , Co(III) /Co(II) and Fe(III) /Fe(II) . Furthermore, the shift in E1/2 is inversely proportional to the nanotube diameter. To quantify the amount of electron transfer from the guest molecules to the SWNTs, a novel method using coulometry was developed, allowing the mapping of the density of states and the Fermi level of the SWNTs. Correlated with theoretical calculations, coulometry provides an accurate indication of n/p-doping of the SWNTs.
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
authors.forename: Robert L
authors.initials: RL
authors.lastname: McSweeney
authors.affiliation: Institute of Process Research & Development, School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Chamberlain
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
authors.forename: Matteo
authors.initials: M
authors.lastname: Baldoni
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.|Department of Materials, Oxford University, Oxford, OX1 3PH, UK.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Lebedeva
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
authors.forename: E Stephen
authors.initials: ES
authors.lastname: Davies
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
authors.forename: Elena
authors.initials: E
authors.lastname: Besley
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK. andrei.khlobystov@nottingham.ac.uk.|National University of Science & Technology, MISiS, Moscow, 119049, Russia. andrei.khlobystov@nottingham.ac.uk.
authors.forename: Andrei N
authors.identifier: http://orcid.org/0000-0001-7738-4098
authors.initials: AN
authors.lastname: Khlobystov
keywords: carbon nanotubes; charge transfer; electrochemistry; host-guest systems; metallocenes