Group 14 Metallafluorenes for Lipid Structure Detection and Cellular Imaging

Fluorescent compounds have been shown to be useful in probing lipid dynamics, and there is ongoing interest in nontoxic, photostable, and sensitive dyes. Recently, we evaluated a number of 2,7-disubstituted-alkynyl(aryl)-3,6-dimethoxy-9,9-diphenyl sila- and germafluorenes for their potential as cellular fluorescent probes. These compounds exhibit remarkable quantum yields in hydrophobic environments and dramatic increases in emission intensity in the presence of surfactants. Here, we show that they exhibit significant emission enhancements in the presence of small unilamellar vesicles and are nontoxic to E. coli, S. aureus, and S. cerevisiae. Furthermore, they luminesce in S. cerevisiae cells with strong photostability and colocalize with the lipid droplet stain Nile Red, demonstrating their promise as lipid probes.