Εξειδίκευση τύπου :	Άρθρο σε επιστημονικό περιοδικό
Τίτλος:	Energy transfer and charge separation dynamics in photoexcited pyrene-bodipy molecular dyads
Δημιουργός/Συγγραφέας:	Fakis M. Beckwith J.S. Seintis K. Martinou E. Nançoz C. Karakostas N. [EL] Πετσαλάκης, Ιωάννης Δ.[EN] Petsalakis, Ioannis D. Pistolis G. Vauthey E.
Εκδότης:	Royal Society of Chemistry
Ημερομηνία:	2018
Γλώσσα:	Αγγλικά
ISSN:	1463-9076
DOI:	10.1039/c7cp06914f
Άλλο:	PubMed ID: 29230451
Περίληψη:	The photophysical properties of two pyrene-bodipy molecular dyads, composed of a phenyl-pyrene (Py-Ph) linked to the meso position of a bodipy (BD) molecule with either H-atoms (BD1) or ethyl groups (BD2) at the 2,6 positions, are investigated by stationary, nanosecond and femtosecond spectroscopy. The properties of these dyads (Py-Ph-BD1 and Py-Ph-BD2) are compared to those of their constituent chromophores in two solvents namely 1,2-dichloroethane (DCE) and acetonitrile (ACN). Stationary spectroscopy reveals a weak coupling among the subunits in both dyads. Excitation of the pyrene (Py) subunit leads to emission that is totally governed by the BD subunits in both dyads pointing to excitation energy transfer (EET) from the Py to BD chromophore. Femtosecond fluorescence and transient absorption spectroscopy reveal that EET takes place within 0.3-0.5 ps and is mostly independent of the solvent and the type of the BD subunit. The EET lifetime is in reasonable agreement with that predicted by Förster theory. After EET has taken place, Py-Ph-BD1 in DCE and Py-Ph-BD2 in both solvents decay mainly radiatively to the ground state with 3.5-5.0 ns lifetimes which are similar to those of the individual BD chromophores. However, the excited state of Py-Ph-BD1 in ACN is quenched having a lifetime of 1 ns. This points to the opening of an additional non-radiative channel of the excited state of Py-Ph-BD1 in this solvent, most probably charge separation (CS). Target analysis of the TA spectra has shown that the CS follows inverted kinetics and is substantially slower than the recombination of the charge-separated state. Occurrence of CS with Py-Ph-BD1 in ACN is also supported by energetic considerations. The above results indicate that only a small change in the structure of the BD units incorporated in the dyads significantly affects the excited state dynamics leading either to a dyad with long lifetime and high fluorescence quantum yield or to a dyad with ability to undergo CS.
Τίτλος πηγής δημοσίευσης:	Physical Chemistry Chemical Physics
Τόμος/Κεφάλαιο:	20
Τεύχος:	2
Σελίδες:	837-849
Θεματική Κατηγορία:	[EL] Φυσική και θεωρητική χημεία[EN] Physical and theoretical chemistry [EL] Φασματοσκοπία[EN] Spectroscopy
Αξιολόγηση από ομότιμους (peer reviewed):	Ναι
Κάτοχος πνευματικών δικαιωμάτων:	© 2018 the Owner Societies.
Σημειώσεις:	University of Patras; Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, SNF: 200020-165890; Université de Genève, UNIGE This work was supported by Grant E.028 from the Research Committee of the University of Patras (Programme K. Karatheodori awarded to Prof. M. Fakis) and by the Fonds National Suisse de la Recherche Scientifique (200020-165890) and the University of Geneva.
Εμφανίζεται στις συλλογές:	Ινστιτούτο Θεωρητικής και Φυσικής Χημείας (ΙΘΦΧ) - Επιστημονικό έργο