Solution and Solid State Structure of a BisBODIPY Fluorophor

Abstract

AbstractThe solution and solid‐state structures of 3,3′‐diethyl‐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 crystallographic analysis resulted in two different conformations for the fluorophor with dihedral angles between the C9N2B 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.