Synthesis of furan-substituted aza-BODIPYs having near-infrared emission

Development of near-infrared-emissive aza-boron dipyrromethene (aza-BODIPY) derivatives having furanyl groups is reported. From the optical measurements, it was clearly indicated that the emission bands were presented in the longer wavelength region than those of the conventional aza-BODIPYs. The emission bands with the peaks at 730 nm and 758 nm were observed from the bis- and tetra-substituted furanyl aza-BODIPYs with similar extents of emission efficiencies, respectively. According to the computer calculations, it was proposed that molecular planarity could be enhanced in the case of the furan groups. As a result, band-gap energy could be lowered comparing to those of the conventional benzene and thiophene-substituted aza-BODIPYs.