DiiodoBodipy-Perylenebisimide Dyad/Triad: Preparation and Study of the Intramolecular and Intermolecular Electron/Energy Transfer

Abstract

2,6-diiodoBodipy-perylenebisimide (PBI) dyad and triad were prepared, with the iodoBodipy moiety as the singlet/triplet energy donor and the PBI moiety as the singlet/triplet energy acceptor. IodoBodipy undergoes intersystem crossing (ISC), but PBI is devoid of ISC, and a competition of intramolecular resonance energy transfer (RET) with ISC of the diiodoBodipy moiety is established. The photophysical properties of the compounds were studied with steady-state and femtosecond/nanosecond transient absorption and emission spectroscopy. RET and photoinduced electron transfer (PET) were confirmed. The production of the triplet state is high for the iodinated dyad and the triad (singlet oxygen quantum yield ΦΔ = 80%). The Gibbs free energy changes of the electron transfer (ΔGCS) and the energy level of the charge transfer state (CTS) were analyzed. With nanosecond transient absorption spectroscopy, we confirmed that the triplet state is localized on the PBI moiety in the iodinated dyad and the triad. An exceptionally long lived triplet excited state was observed (τT = 150 μs) for PBI. With the uniodinated reference dyad and triad, we demonstrated that the triplet state localized on the PBI moiety in the iodinated dyad and triad is not produced by charge recombination. These information are useful for the design and study of the fundamental photochemistry of multichromophore organic triplet photosensitizers.

Energy/Electron Transfer Switch for Controlling Optical Properties of Silicon Quantum Dots

“…Kinetic traces for Urea-SQD-Per monitored at PDI emission were fit to a mono exponential equation where the extracted lifetime found to be ~4.4 ns. This finding is in good agreement with literature data for PDI-based compunds 50 . Kinetic traces corresponding to SQDs emission maxima revealed three components: one fast together with two of relatively longer lifetimes.…”

Highly Efficient Triplet Photosensitizers: A Systematic Approach to the Application of IrIII Complexes containing Extended Phenanthrolines

“…The spin density surface of the complex indicates the localization of triplet excited states. [31] Thus for complexes Ir-1 and Ir-2,the spin density of the triplet state was determined to be distributed over the Ir III centrea nd the coordinated TPA-phenanthroline ligand,i ndicating the 3 MLCT feature of the triplet excited states. However,i nIr-3,t he spin density is confined on the pyrene but not the TPAm oiety.T he contribution to the spin density by the metal centera nd the auxiliary ligand appears to be minimal.…”

The triplet excited state of Bodipy: formation, modulation and application

“…These results infer that the singlet excited state of diiodoBodipy was trapped somehow from decaying by the FRET. 212 Intermolecular triplet energy transfer between the diiodoBodipy and PBI reference compounds were studied by using ns TA spectroscopy. Upon selective photoexcitation of the diiodoBodipy in the mixture, the transient absorption spectrum of the diiodoBodipy diminished.…”