title: pi-Conjugated multidonor/acceptor arrays of fullerene-cobaltadithiolene-tetrathiafulvalene: from synthesis and structure to electronic interactions.
abstract: The synthesis, structure, photoelectrochemical behavior, and nonlinear optical (NLO) properties of a symmetric acceptor-acceptor-donor-acceptor-acceptor array, C(60)-Co-TTF-Co-C(60), have been described. The precursors, namely, cobalt dicarbonyl complexes Co(C(60)Ar(5))(CO)(2) were synthesized from the penta(organo)[60]fullerenes, C(60)Ar(5)H, as starting materials. In the next step, two cobalt-fullerene complexes were connected to a tetrathiafulvalene (TTF) tetrathiolate bridge to obtain the C(60)-Co-TTF-Co-C(60) array. In addition, the monomeric compounds, Co(C(60)Ar(5))(S(2)C(2)R(2)) (R = CO(2)Me and CN) and Co(C(60)Ar(5))(S(2)C(2)S(2) C = CS(2)C(2)R(2)) were synthesized as references. The C(60)-Co-TTF-Co-C(60) array exhibits very strong transitions in the near-infrared region (lambda(max) = 1,100 nm, epsilon = 30 000 M(-1) x cm(-1)) due to a ligand-to-metal-charge-transfer (LMCT) transition and six reversible electron transfer processes. In the crystal, a fullerene/TTF-layered packing structure is evident. Femtosecond flash photolysis revealed that photoexcitation of the array results in a charge separated state involving the strongly interacting cobaltadithiolene and TTF constituents which electronically relax via a resonance effect that extends all throughout the acceptor parts of the C(60)-Co-TTF-Co-C(60) array. The third-order NLO measurement of the array gave the magnitude of the third-order nonlinear susceptibility, |chi((3))|, values to be 9.28 x 10(-12) esu, suggesting the pi-conjugation of donors and acceptors in the array.
authors: Nakamura Functional Carbon Cluster Project, ERATO, Japan Science and Technology Agency, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. matsuo@chem.s.u-tokyo.ac.jp
authors: Yutaka
authors: Y
authors: Matsuo
authors: Masashi
authors: M
authors: Maruyama
authors: S Shankara
authors: SS
authors: Gayathri
authors: Tomoya
authors: T
authors: Uchida
authors: Dirk M
authors: DM
authors: Guldi
authors: Hideo
authors: H
authors: Kishida
authors: Arao
authors: A
authors: Nakamura
authors: Eiichi
authors: E
authors: Nakamura
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004583:Electrons; D037741:Fullerenes / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
chemical_list: D037741:Fullerenes; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; D003035:Cobalt; C063887:tetrathiafulvalene