Insights into the Structure–Property Relationship of Difluoro Boron Dipyridomethene Derivatives

Abstract

To elucidate the molecular structure of the difluoro dipyridomethene system and to establish structure–property relationships, an extensive synthetic work is reported. Four classes of novel fluorescent BF₂-DIPYR complexes are prepared via Suzuki–Miyaura cross-coupling reaction from the corresponding mono- and bis-brominated dyes in moderate to good yields. The strategy allows the introduction of a large panel of electron-donating and -withdrawing groups on the meso, 3 and/or 7 position of the aromatic BF₂-DIPYR core. The new symmetric and asymmetric mono-, bis-, and tris substituted dyes are thoroughly characterized by X-ray diffraction analysis and spectroscopic measurements. Furthermore, the latter are rationalized by TD-DFT calculations.