PUB - Publikationen an der Universität Bielefeld

Reaction of 2,5-bis(dibromoboryl)thiophene (4) or 1,4-bis(dibromoboryl)benzene (6) with two equivalents of N,N'-dilithiated 2,3-diaminopyridine (3) led to the generation of the pyridodiazaboroles 5 and 7 in which the two diazaborole rings are linked by 2,5-thiophen-diyl or 1,4-phenylene units via the boron atom. The novel compounds were characterized by elemental analyses and spectroscopy (H-1-, B-11-, C-13-NMR, MS, and UV-VIS). The molecular structure of 5 was elucidated by X-ray diffraction. Cyclovoltammograms of 5 and 7 show two irreversible oxidation waves at 0.76 and 0.73 V, respectively vs Fc/Fc(+). The novel compounds display intense blue luminescence with Stokes shifts of 76 and 74 nm and relative quantum yields of 39 and 43% vs Coumarin 120 (phi = 50%).