Tuning the optical properties of BODIPY dyes by N-rich heterocycle conjugation using a combined synthesis and computational approach

The increased number of N-atoms induced a blueshift in absorption and a gain in fluorescence quantum yield, from 750 nm and similar to 0% for pyrrole to 635 nm and similar to 40% for triazole, respectively. DFT calculations indicated a decrease in HOMO energy levels with the increased number of N-atoms without affecting the LUMO levels, thereby causing the observed blueshift.