Synthesis of a pyrene-fused aza-BODIPY as a near-infrared dye having the absorption maximum at 746nm

A novel pyrene-fused pyrrole was developed by the reaction of 9,10-dihydrobenzo[pqr]tetraphen-7(8H)-one with 3-phenyl-2H-azirine in the presence of NaH. Utilizing this pyrrole, the symmetric pyrene-containing aza-BODIPY has been prepared in the NIR region (λabs=746nm, λem=762nm) as a result of the combined effect of the rigidization and the extension of the π-conjugation. The decrease in the HOMO–LUMO band gap for the lowest energy absorption bands was observed in the pyrene-fused aza-BODIPY.