Efficient Utilization of Higher-Lying Excited States to Trigger Charge-Transfer Events

Pierre-Antoine Bouit (1) , Fabian Spänig , Gregory Kuzmanich , Evangelos Krokos , Christian Oelsner , Miguel a. Garcia-Garibay , Juan luis Delgado , Nazario Martín , Dirk m. Guldi

1 ISCR - Institut des Sciences Chimiques de Rennes

Several new fullerene- heptamethine conjugates absorbing as far as 800 nm have been synthesized and fully characterized by physic-chemical means. In terms of optical and electrochemical characteristics appreciable electronic coupling between both electroactive species is deduced. The latter also reflects the excited state features. To this end, time resolved transient absorption measurements revealed that photoexcitation is followed by a sequence of charge transfer evolving from higher singlet excited states (i.e., S2 – fast charge transfer) and the lowest singlet excited state (i.e., S1 – slow charge transfer) of the heptamethine cyanine as electron donor to an either covalently linked C60 or C70 as electron acceptor. Finally, charge transfer from photoexcited C60 / C70 completes the charge transfer sequence. The slow internal conversion within the light harvesting heptamethine cyanine and the strong electronic coupling between the individual constituents are particularly beneficial.

Domains: Chemical Sciences; Organic chemistry; Chemical Sciences; Theoretical and/or physical chemistry

Pierre-Antoine Bouit, Fabian Spänig, Gregory Kuzmanich, Evangelos Krokos, Christian Oelsner, et al.. Efficient Utilization of Higher-Lying Excited States to Trigger Charge-Transfer Events. Chemistry - A European Journal, 2010, 16 (31), pp.9638-9645. ⟨10.1002/chem.201001613⟩. ⟨hal-01089804⟩