title: (Terpyridine)copper(II)-carbon nanohorns: metallo-nanocomplexes for photoinduced charge separation.
abstract: New metallo-nanostructured materials of carbon nanohorns (CNHs), within the family of elongated carbon nanotubes, have been prepared by the coordination of copper(II)-2,2':6',2' '-terpyridine (Cu(II)tpy) with oxidized carbon nanohorns (CNHs-COOH). The resulted CNHs-COO-Cu(II)tpy metallo-nanocomplexes have been characterized by diverse analytical spectroscopic tools and cyclic and differential pulse voltammetry. Scanning transmission electron microscopy (STEM), dynamic light scattering (DLS), and energy dispersive X-ray spectroscopy (EDX) measurements have been employed to probe the morphological characteristics and particle-size distribution of CNHs-COO-Cu(II)tpy as well as to investigate the elemental composition of the metallo-nanocomplex. Steady-state and time-resolved fluorescence emission studies have shown efficient fluorescence quenching, suggesting that electron transfer occurs from the singlet excited state of Cu(II)tpy to CNHs. Photoexcitation of Cu(II)tpy resulted in the one-electron reduction of nanohorns with a simultaneous one-electron oxidation of the Cu(II)tpy unit (CNHs(*-)-COO-(Cu(II)tpy)*+) as revealed by transient absorption measurements. The charge-separated state of CNHs(*-)-COO-(Cu(II)tpy)*+ has been confirmed with the aid of an electron mediator, such as hexyl-viologen dication (HV2+) and an electron-hole shifter in polar solvents.
authors.affiliation: Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Ave., Athens 116 35, Greece.
authors.forename: Georgios
authors.initials: G
authors.lastname: Rotas
authors.forename: Atula S D
authors.initials: AS
authors.lastname: Sandanayaka
authors.forename: Nikos
authors.initials: N
authors.lastname: Tagmatarchis
authors.forename: Toshinari
authors.initials: T
authors.lastname: Ichihashi
authors.forename: Masako
authors.initials: M
authors.lastname: Yudasaka
authors.forename: Sumio
authors.initials: S
authors.lastname: Iijima
authors.forename: Osamu
authors.initials: O
authors.lastname: Ito