Pyrrolopyrrole Aza-BODIPY Analogues as Near-Infrared Chromophores and Fluorophores: Red-Shift Effects of Substituents on Absorption and Emission Spectra.

Pyrrolopyrrole aza-BODIPY analogues (PPABs) are a new class of UV/vis and near-infrared chromophores. Varying the substituents results in red-shifts of both the absorption and emission spectra. Extension of the lengths of the oligothiophene substituents from thiophene to quaterthiophene caused red-shifts of the absorption and emission from 699 and 712 nm to 809 and 853 nm, respectively. The piperidylthiophene-substituted PPAB exhibited similar red-shifts of the absorption and emission to 810 and 831 nm, respectively, although only a single thienyl component is present, because of the strong electron-donating nature of the piperidine substituent.