Unravelling the ultrafast dynamics of a N-BODIPY compound
Authors: Doria S.; Taddei M.; Cupellini L.; Biagiotti G.; Bartolini P.; Bussotti L.; Cicchi S.; Foggi P.; Mennucci B.; Di Donato M.
Autors Affiliation: ICCOM-CNR, via Madonna del Piano 10, FI, Sesto Fiorentino, I-50019, Italy; LENS (European Laboratory for Non-Linear Spectroscopy), Via N. Carrara 1, FI, Sesto Fiorentino, 50019, Italy; Dipartimento di Chimica “”Ugo Schiff””, Universitb degli Studi di Firenze, via della Lastruccia, 3-13, Sesto Fiorentino, Florence, 50019, Italy; Dipartimento di Chimica e Chimica Industriale, Universitb di Pisa, via G. Moruzzi 13, Pisa, 56124, Italy; Department of Chemistry, Biology and Biotechnology, Centro di Eccellenza sui Materiali Innovativi Nanostrutturati (CEMIN), University of Perugia, via Elce di Sotto 8, Perugia, 06123, Italy; INO-CNR, Largo Fermi 6, Firenze, 50125, Italy.
Abstract: Although the photophysics of BODIPY compounds has been widely investigated in the last few years, their analogues N-BODIPY, with nitrogen substitution at the boron center, did not receive comparable attention. In this work we report the synthesis and photochemical characterization of a substituted N-BODIPY compound, by means of a combined theoretical and spectroscopic approach. Compared to a standard BODIPY, the compound under investigation presents a lower fluorescence quantum yield (QY) in the visible region. The excited state relaxation dynamics of the dye was studied in different solvents, showing further fluorescence quenching in polar solvents, and excited state decay rates strongly dependent on the environment polarity. The role of the pendant moieties and the involvement of charge transfer states in the excited state dynamics was experimentally addressed by transient absorption spectroscopy, and further analyzed with TD-DFT calculations, which allowed precise assignment of the transient signals to the correspondent electronic configuration. The complete picture of the N-BODIPY behavior shows the presence of both charge transfer and localized states, influencing the observed photophysics to different amounts, depending on the excitation conditions and the surrounding environment.
Journal/Review: DYES AND PIGMENTS
Volume: 200 Pages from: 110181-1 to: 110181-8
More Information: The authors thank the European Union´s Horizon 2020 research and innovation program under grant agreement n. 871124 Laserlab-Europe.
The authors also thank Dr Lorenzo Zani, Dr Massimo Calamnte and Dr Alessio Dessi from ICCOM-CNR in Sesto Fiorentino (FI), for support in the quantum yield measurements.
LC thanks the funding by the European Research Council, under the grant ERC-AdG-786714 (LIFETimeS).KeyWords: Charge transfer states; DFT computations; N-BODIPY; Transient absorption spectroscopy; PHOTOINDUCED ELECTRON-TRANSFERENERGY-TRANSFERFLUORESCENT SENSORSCHARGE-TRANSFEREXCITED-STATESBORON-DIPYRRINDYE-LASERSDESIGNVERSATILECHEMISTRYDOI: 10.1016/j.dyepig.2022.110181