Scientific Results

Efficient Photoinduced Charge Separation in a BODIPY-C-60 Dyad

Year: 2016

Authors: Iagatti A., Cupellini L., Biagiotti G., Caprasecca S., Fedeli S., Lapini A., Ussano E., Cicchi S., Foggi P., Marcaccio M., Mennucci B., Di Donato M.

Autors Affiliation: LENS (European Laboratory for Nonlinear Spectroscopy), via N. Carrara 1, Sesto Fiorentino, 50019, Italy; INO-CNR (Istituto Nazionale di Ottica), Largo Fermi 6, Firenze, 50125, Italy; Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via G. Moruzzi 13, Pisa, 56124, Italy; Dipartimento di Chimica Ugo Schiff, Università di Firenze, via della Lastruccia 13, Sesto Fiorentino, 50019, Italy; Dipartimento di Chimica G. Ciamician, Università di Bologna, via Selmi 2, Bologna, 40126, Italy; Dipartimento di Chimica, Università di Perugia, via Elce di Sotto 8, Perugia, 06100, Italy

Abstract: A donor acceptor dyad composed of a BF2-chelated dipyrromethene (BODIPY) and a C-60 fullerene has been newly synthesized and characterized. The two moieties are linked by direct addition of an azido substituted BODIPY on the C-60, producing an imino fullerene BODIPY adduct. The photoinduced charge transfer process in this system was studied by ultrafast transient absorption spectroscopy. Electron transfer toward the fullerene was found to occur selectively exciting both the BODIPY chromophore at 475 nm and the C-60 unit at 266 nm on a time scale of a few picoseconds, but the dynamics of charge separation was different in the two cases. Eletrochemical studies provided information on the redox potentials of the involved species and spectroelectrochemical measurements allowed to unambiguously assign the absorption band of the oxidized BODIPY moiety, which helped in the interpretation of the transient absorption spectra. The experimental studies were complemented by a theoretical analysis based on DFT computations of the excited state energies of the two components and their electronic couplings, which allowed identification of the charge transfer mechanism and rationalization of the different kinetic behavior observed by changing the excitation conditions.

Journal/Review: JOURNAL OF PHYSICAL CHEMISTRY C

Volume: 120 (30)      Pages from: 16526  to: 16536

KeyWords: Absorption spectroscopy; Charge transfer; Chromophores; Electron transport properties; Fullerenes; Redox reactions; Spectroelectrochemistry, Charge transfer mechanisms; Excitation conditions; Excited-state energy; Photoinduced charge separation; Photoinduced charge transfer; Spectroelectrochemical measurements; Transient absorption spectra; Ultrafast transient absorption spectroscopy, Excited states
DOI: 10.1021/acs.jpcc.6b05738

Citations: 14
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