title: Fullerene-Assisted Photoinduced Charge Transfer of Single-Walled Carbon Nanotubes through a Flavin Helix.
abstract: One of the greatest challenges with single-walled carbon nanotube (SWNT) photovoltaics and nanostructured devices is maintaining the nanotubes in their pristine state (i.e., devoid of aggregation and inhomogeneous doping) so that their unique spectroscopic and transport characteristics are preserved. To this effect, we report on the synthesis and self-assembly of a C60-functionalized flavin (FC60), composed of PCBM and isoalloxazine moieties attached on either ends of a linear, C-12 aliphatic spacer. Small amounts of FC60 (up to 3 molar %) were shown to coassembly with an organic soluble derivative of flavin (FC12) around SWNTs and impart effective dispersion and individualization. A key annealing step was necessary to perfect the isoalloxazine helix and expel the C60 moiety away from the nanotubes. Steady-state and transient absorption spectroscopy illustrate that 1% or higher incorporation of FC60 allows for an effective photoinduced charge transfer quenching of the encased SWNTs through the seamless helical encase. This is enabled via the direct π-π overlap between the graphene sidewalls, isoalloxazine helix, and the C60 cage that facilitates SWNT exciton dissociation and electron transfer to the PCBM moiety. Atomistic molecular simulations indicate that the stability of the complex originates from enhanced van der Waals interactions of the flexible spacer wrapped around the fullerene that brings the C60 in π-π overlap with the isoalloxazine helix. The remarkable spectral purity (in terms of narrow E(S)ii line widths) for the resulting ground-state complex signals a new class of highly organized supramolecular nanotube architecture with profound importance for advanced nanostructured devices.
authors.affiliation: Nanomaterials Optoelectronics Laboratory (NOEL), Polymer Program, Institute of Materials Science, ‡Department of Chemistry, and §Department of Physics, University of Connecticut , Storrs, Connecticut 06269, United States.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Mollahosseini
authors.affiliation: Nanomaterials Optoelectronics Laboratory (NOEL), Polymer Program, Institute of Materials Science, ‡Department of Chemistry, and §Department of Physics, University of Connecticut , Storrs, Connecticut 06269, United States.
authors.forename: Erandika
authors.initials: E
authors.lastname: Karunaratne
authors.affiliation: Nanomaterials Optoelectronics Laboratory (NOEL), Polymer Program, Institute of Materials Science, ‡Department of Chemistry, and §Department of Physics, University of Connecticut , Storrs, Connecticut 06269, United States.
authors.forename: George N
authors.initials: GN
authors.lastname: Gibson
authors.affiliation: Nanomaterials Optoelectronics Laboratory (NOEL), Polymer Program, Institute of Materials Science, ‡Department of Chemistry, and §Department of Physics, University of Connecticut , Storrs, Connecticut 06269, United States.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Gascón
authors.affiliation: Nanomaterials Optoelectronics Laboratory (NOEL), Polymer Program, Institute of Materials Science, ‡Department of Chemistry, and §Department of Physics, University of Connecticut , Storrs, Connecticut 06269, United States.
authors.forename: Fotios
authors.initials: F
authors.lastname: Papadimitrakopoulos
mesh_terms: D003198:Computer Simulation; D005415:Flavins / Q000737:chemistry*; D037741:Fullerenes / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry; D007202:Indicators and Reagents; D008958:Models, Molecular; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D037742:Nanotubes, Carbon / Q000737:chemistry*; D055668:Photochemical Processes
chemical_list: D005415:Flavins; D037741:Fullerenes; D007202:Indicators and Reagents; D037742:Nanotubes, Carbon; D006108:Graphite