Emissive Oxygen Bridged Pyridine Phenolate Boron Complex

The exploration of new boron-based luminescent materials offers opportunities for advancing optoelectronic, sensing, and photonic applications. In this study, we describe the synthesis, structural analysis, and photophysical characterization of an oxygen-bridged diboron complex (BOB) supported by an O^N^O ligand framework, together with its fluorinated monomeric analogue (BF). Single-crystal X-ray diffraction revealed that BF adopts a nearly ideal tetrahedral environment at boron central atom, whereas BOB exhibits significantly distorted tetrahedral geometries, characterized by broader angular dispersions and elongated B-X bond lengths induced by the oxygen bridge. Electrochemical investigations demonstrated high stability across a wide potential window, with BOB undergoing a quasi-reversible oxidation at +1.20 V vs. Fc/Fc+. Fluorinated monomeric species (BF) being very similar to the already reported 2,2′-(pyridine-2,6-diyl)diphenolate (dppy) systems were obtained after reaction with NOPF6. Photophysical studies revealed that BOB displays red-shifted and more intense absorption features (400, 357, 306 nm) compared to BF (383, 330 nm). Both complexes emit in the visible region, with maximum intensity at 483 nm (BOB) and 474 nm (BF). Time-resolved spectroscopy proved similar excited-state lifetimes (3.57 and 3.89 ns, respectively) and moderate quantum yields (Φ = 0.15 and 0.18). These results identify oxygen-bridged diboron systems as structurally distinctive yet underexplored scaffolds, offering new opportunities for tailoring emissive boron chromophores through ligand and framework design.