A series of new compds. in which various Bodipy dyes are grafted logically on triptycene rigid structures are synthesized and characterized, and their absorption spectra and photophys. properties are studied, also by pump-probe transient absorption spectroscopy. The studied compds. are: the mono-Bodipy species TA, TB, and TC (where A, B, and C identify different Bodipy subunits absorbing and emitting at different wavelengths), the multichromophore species TA3, which bears three identical A subunits, and the three multichromophoric species TAB, TBC, and TABC, all of them contg. at least two different types of Bodipy subunits. The triptycene moiety plays the role of a rigid scaffold, keeping the various dyes at predetd. distances and allowing for a three-dimensional structural arrangement of the multichromophoric species. The absorption spectra of the multichromophoric Bodipy species are essentially additive, indicating that negligible inter-chromophoric interaction takes place at the ground state. Luminescence properties and transient absorption spectroscopy indicate that a very fast (on the picosecond time scale) and efficient photoinduced energy transfer occurs in all the multi-Bodipy species, with the lower-energy Bodipy subunits of each multi-Bodipy compds. playing the role of an electronic energy collector. In TAB, an energy transfer from the A-type Bodipy subunit to the B-type one takes place with a rate const. of 1.6×1010 s-1, whereas in TBC an energy transfer from the B-type Bodipy subunit to the C-type subunit is bi-exponential, exhibiting rate consts. of 1.7×1011 and 1.9×1010 s-1; the possible presence of different conformers with different donor-acceptor distances in this bichromophoric species is proposed to cause the bi-exponential energy-transfer process. Interpretation of the intricate energy-transfer pathways occurring in TABC is made with the help of the processes identified in the bichromophoric compds. In all cases, the measured energy-transfer rate consts. agree with a Foerster mechanism for the energy-transfer processes.

Ultrafast Energy Transfer in Triptycene-Grafted Bodipy Scaffoldings

NASTASI, FRANCESCO;PUNTORIERO, Fausto;CAMPAGNA, Sebastiano;
2013-01-01

Abstract

A series of new compds. in which various Bodipy dyes are grafted logically on triptycene rigid structures are synthesized and characterized, and their absorption spectra and photophys. properties are studied, also by pump-probe transient absorption spectroscopy. The studied compds. are: the mono-Bodipy species TA, TB, and TC (where A, B, and C identify different Bodipy subunits absorbing and emitting at different wavelengths), the multichromophore species TA3, which bears three identical A subunits, and the three multichromophoric species TAB, TBC, and TABC, all of them contg. at least two different types of Bodipy subunits. The triptycene moiety plays the role of a rigid scaffold, keeping the various dyes at predetd. distances and allowing for a three-dimensional structural arrangement of the multichromophoric species. The absorption spectra of the multichromophoric Bodipy species are essentially additive, indicating that negligible inter-chromophoric interaction takes place at the ground state. Luminescence properties and transient absorption spectroscopy indicate that a very fast (on the picosecond time scale) and efficient photoinduced energy transfer occurs in all the multi-Bodipy species, with the lower-energy Bodipy subunits of each multi-Bodipy compds. playing the role of an electronic energy collector. In TAB, an energy transfer from the A-type Bodipy subunit to the B-type one takes place with a rate const. of 1.6×1010 s-1, whereas in TBC an energy transfer from the B-type Bodipy subunit to the C-type subunit is bi-exponential, exhibiting rate consts. of 1.7×1011 and 1.9×1010 s-1; the possible presence of different conformers with different donor-acceptor distances in this bichromophoric species is proposed to cause the bi-exponential energy-transfer process. Interpretation of the intricate energy-transfer pathways occurring in TABC is made with the help of the processes identified in the bichromophoric compds. In all cases, the measured energy-transfer rate consts. agree with a Foerster mechanism for the energy-transfer processes.
2013
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/2552634
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