Observation of the triplet energy transfer in orthogonal photoexcited iodinated-BODIPY dimers

Abstract

Intramolecular charge and energy transfer processes initiated by light absorption can change the photosensitization properties of molecular conjugates. Transient optical and electron paramagnetic resonance (TREPR) spectroscopies are well suited for...

A Rational Way to Control the Triplet State Wave Function Confinement of Organic Chromophores: Effect of the Connection Sites and Spin Density Distribution-Guided Molecular Structure Design Principles in Bodipy Dimers

“…Another explanation for the reduced ZFS could be the exciton hopping between two localized triplet states as proposed for some other Bodipy dimers. 47,49,63 However, additional measurements at a lower temperature (40 K) do not show any changes in the spectral properties of dimer DB2. Therefore, there are no transitions between two triplet sites separated by the energy barrier, and we conclude that these samples show delocalization of the triplet state over the whole molecule.…”

“…All TREPR spectra show a significant reduction of the ZFS parameters compared to those of the (iodinated) monomers or other dimers with the orthogonal chromophores (∼80 mT). , It should be noted that the trend toward reduction of ZFS was observed earlier in 2,6′-diiodoBodipy and Bodipy derivatives that have large π-conjugation frameworks. ,, ZFS parameter D of DB1 and DB2 is only half that of the monomers. , The substantial decrease in the ZFS reveals a significant delocalization of the wave function of the triplet state over two subunits in the dimer molecular structures. Another explanation for the reduced ZFS could be the exciton hopping between two localized triplet states as proposed for some other Bodipy dimers. ,, However, additional measurements at a lower temperature (40 K) do not show any changes in the spectral properties of dimer DB2 . Therefore, there are no transitions between two triplet sites separated by the energy barrier, and we conclude that these samples show delocalization of the triplet state over the whole molecule.…”