- Solution and solid state structure of a BisBODIPY fluorophor
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The solution and solid-state structures of 3,3′-d.iethyl-4,4′, 8,8′,9,9′,10,10′-octamethyl-6,6′-di-p-tolyl-bisBODIPY, a potent fluorescent dye, were examined by X-ray diffraction and NMR spectroscopy. The crystallography analysis resulted in two different conformations for the fluorophor with, dihedral angles between the C 9N2B subunits of 91.9 and 96.8°. The presence of two different conformations is a consequence of the crystal packing as the 3D structure is composed of alternating layers of BisBODIPY molecules with and without cocrystallized solvent. In solution NMR spectroscopic studies the compound displays intramolecular and distance dependant through space C-F and F-F couplings, which were used to analyze the solution structure. This analysis suggests a single minimum conformation and a rigid, but unstrained structure in solution. The fluorescence properties of the BisBODIPY and in particular the high quantum yields found for this class of luminophores are qualitatively in agreement with the latter result, and better described by the solution structure than by the solid-state structure.
- Broering, Martin,Yuan, Yuan,Krueger, Robin,Kleeberg, Christian,Xie, Xiulan
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- Bis(BF2)-2,2′-bidipyrrins (BisBODIPYs): Highly fluorescent BODIPY dimers with large stokes shifts
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Four new dimeric bis(BF2)-2,2′-bidipyrrins (bisBODIPYs), and their corresponding BODIPY monomers, have been prepared and studied with respect to their structural and photophysical properties. The solidstate molecular structure of the dimers and the relative orientation of the subunits have been revealed by an X-ray diffraction study, which showed that the molecules contain two directly linked BODIPY chromophores in a conformationally fixed, almost orthogonal arrangement. Two of the fluorine atoms are in close contact with each other and the 19F NMR spectra show a characteristic through-space coupling in solution. The new chromophores all exhibit a clear exciton splitting in the absorption spectra with maxima at about 490 and 560 nm, and are highly luminescent with an intense emission band at around 640 nm. The Stokes shift, which is the difference between the maximum of the lowest-energy absorption band and the maximum of the emission band, has a typical value of 5 to 15 nm for simple BODIPYs, whereas this value increases to 80 nm or more for the dimers, along with a slight decrease in fluorescence quantum yields and lifetimes. These properties indicate potential uses of these new fluorophoric materials as functional dyes in biomedical and materials applications and also in model compounds for BODIPY aggregates.
- Broering, Martin,Krueger, Robin,Link, Stephan,Kleeberg, Christian,Koehler, Silke,Xie, Xiulian,Ventura, Barbara,Flamigni, Lucia
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experimental part
p. 2976 - 2983
(2009/04/08)
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