Fluorescent BODIPY-Anionic Boron Cluster Conjugates as Potential Agents for Cell Tracking

A series of novel fluorescent BODIPY-anionic boron cluster conjugates bearing [B12H12]2– (5, 6), [3,3′-Co(1,2-C2B9H11)2]− (7, 8), and [3,3′-Fe(1,2-C2B9H11)2]− (9) anions have been readily synthesized from meso-(4-hydroxyphenyl)-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY 4), and their structure and photoluminescence properties have been assessed. Linking anionic boron clusters to the BODIPY (4) does not alter significantly the luminescent properties of the final fluorophores, showing all of them similar emission fluorescent quantum yields (3–6%). Moreover, the cytotoxicity and cellular uptake of compounds 5–9 have been analyzed in vitro at different concentrations of B (5, 50, and 100 μg B/mL) using HeLa cells. At the lowest concentration, none of the compounds shows cytotoxicity and they are successfully internalized by the cells, especially compounds 7 and 8, which exhibit a strong cytoplasmic stain indicating an excellent internalization efficiency. To the best of our knowledge, these are the fi...