Methoxylated bis(pentafluorophenyl)boron-β-diketonates: Synthesis, Optical Properties and Hydrolytic Stability

A series of methoxylated bis(pentafluorophenyl)boron-β-diketonates (dkB(C₆F₅)₂) with intense emission has been synthesized and characterized by a variety of physicochemical methods. The photophysical properties of the synthesized compounds were thoroughly investigated by electronic absorption, steady-state, and time-resolved fluorescence spectroscopy in both solution and solid state. The studied compounds exhibit solvatochromic behavior attributed to the intramolecular charge transfer (ICT) nature of the first excited state. The formation of exciplexes between DBMB(C₆F₅)₂ and benzene derivatives was also studied. Notably, the studied compounds display a complex luminescence profile in the solid state, featuring fluorescence, delayed fluorescence and phosphorescence emission. Furthermore, the hydrolytical stability of the complexes was assessed, demonstrating excellent resistance to hydrolysis. Estimated rate constants, determined at 60 °C, are significantly lower (90-2000 times) than those observed for the well-studied dibenzoylmethanatoboron difluoride (DBMBF₂). The incorporation of pentafluorophenyl substituents at the boron atom enables the synthesis of highly fluorescent and hydrolytically stable boron chelate complexes, suitable for sensing and bioimaging applications in water-containing environments.