title: How close can you get? Studies of ultrafast light-induced processes in ruthenium-[60] fullerene dyads with short pyrazolino and pyrrolidino links.
abstract: Two pyrazoline- and one pyrrolidine-bridged Ru(II)bipyridine-[60]fullerene dyads have been prepared and studied by ultrafast time-resolved spectroscopy. A silver-assisted synthesis route, in which Ag(I) removes the chlorides from the precursor complex Ru(bpy) 2Cl 2 facilitates successful coordination of the [60]fullerene-substituted third ligand. Upon light excitation of the ruthenium moiety, the emission was strongly quenched by the fullerene. The main quenching mechanism is an exceptionally fast direct energy transfer ( k obs > 1 x 10 (12) s (-1) in the pyrazoline-bridged dyads), resulting in population of the lowest excited triplet state of fullerene. No evidence for electron transfer was found, despite the extraordinarily short donor-acceptor distance that could kinetically favor that process. The observations have implications on the ongoing development of devices built from Ru-polypyridyl complexes and nanostructured carbon, such as C 60 or nanotubes.
authors.affiliation: Department of Biochemistry and Organic Chemistry, Uppsala University, Box 576, SE- 751 24 Uppsala, Sweden.
authors.forename: Susanne
authors.initials: S
authors.lastname: Karlsson
authors.forename: Judit
authors.initials: J
authors.lastname: Modin
authors.forename: Hans-Christian
authors.initials: HC
authors.lastname: Becker
authors.forename: Leif
authors.initials: L
authors.lastname: Hammarström
authors.forename: Helena
authors.initials: H
authors.lastname: Grennberg
mesh_terms: D000042:Absorption; D004563:Electrochemistry; D004579:Electron Transport; D004735:Energy Transfer; D037741:Fullerenes / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D011720:Pyrazoles / Q000737:chemistry*; D011759:Pyrrolidines / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013997:Time Factors
chemical_list: D037741:Fullerenes; D009942:Organometallic Compounds; D011720:Pyrazoles; D011759:Pyrrolidines; C031280:pyrazole; D012428:Ruthenium; C032519:pyrrolidine; C069837:fullerene C60