β-Furan-Fused bis(Difluoroboron)-1,2-bis((1H-pyrrol-2-yl)methylene)hydrazine Fluorescent Dyes in the Visible Deep-Red Region

Novel β-furan-fused bis(difluoroboron)-1,2-bis((1H-pyrrol-2-yl)methylene)hydrazine (BOPHY) fluorescent dyes (F-BOPHY1-3) were prepared through an efficient process, and their structures were confirmed by (1)H NMR spectroscopy, (13)C NMR spectroscopy, MALDI-TOF HRMS, and element analysis. Their optical properties were then characterized by UV-vis absorption and photoluminescence (PL) spectroscopy. The UV-vis absorption and PL spectra of the dyes shifted to longer wavelengths relative to those of BOPHY because of the fusion of their furan rings, which extended π-conjugation of the molecules. All of the dyes exhibited large extinction coefficients (109700-12300 M(-1) cm(-1)), deep-red fluorescence emission (646-667 nm), moderate fluorescence quantum yields (0.30-0.45), as well as high chemical stability and photostability in solution. These advantageous properties show that these compounds are important to the design of efficient long-wavelength fluorescent dyes and are suitable for various applications in biotechnology and materials science.