Design, Synthesis, and Chemical Characterization of Pyrene-Substituted BODIPY Dyes

In this study, novel di- and tetra-pyrenylated BODIPY (boron-dipyrromethene) dyes (Bdpy2 and Bdpy4) were synthesized via the Suzuki-Miyaura cross-coupling reaction, incorporating pyrene units at specific positions on the BODIPY core. Comprehensive structural characterization was achieved through FT-IR, UV-Vis, MALDI-mass spectrometry, and NMR techniques. The optical properties were extensively analyzed in different solvents, revealing Q-band absorption maxima at 531 nm for Bdpy2 and 533 nm for Bdpy4 in THF, along with red-shifted emission peaks due to increased π–π stacking interactions. Bdpy4 displayed a fluorescence quantum yield of 0.68 and a fluorescence lifetime of 3.88 ns, surpassing Bdpy2′s values of 0.61 and 3.44 ns, respectively. These improved values in Bdpy4 highlight the enhanced energy transfer efficiency provided by the additional pyrene groups. Theoretical TD-DFT calculations supported the experimental findings, indicating effective energy transfer from pyrene to the BODIPY core. These findings suggest that the high fluorescence efficiency and extended lifetimes of pyrenylated BODIPY derivatives make them promising candidates for optoelectronic applications, including bioimaging and energy harvesting.