International 10. Drug Chemistry Conference, Antalya, Turkey, 10 - 13 March 2022, pp.44
Developing small fluorescent organic dyes with large Stokes shifts, which can minimize cross-talk
between the excitation source and the fluorescent emission for cellular imaging, is crucial in cell
imaging to probe biological dynamics and monitor RNA and DNA at the cellular level.1
In our previous
studies related to the ESIPT mechanism, we found that compounds with disubstituted imidazole rings
have remarkable fluorescence properties and large Stokes shifts. One of our imidazole derivatives (Bk6) was a fluorescence sensor sensitive to intracellular pH changes, with a Stokes shift of 143
nanometres, and another derivative was sensitive to Fe3+ ions with a Stokes shift of 107 nm.
In addition, the commercially available fluorescent organic dyes, such as nil red dyes, cyanine dyes,
have Stokes shifts below 70 nm and lead to undesired background interferences.3 To cope with this
issue, we developed a series of possible fluorophore dyes with large Stokes shifts (Δλ ≥ 100 nm), as
well as a fluorescence library of mono- and di-substituted imidazole molecules, to examine the
intracellular fluorescence dye properties of the molecules with the best fluorescence activity. As a result, ten of the synthesized molecules showed Stokes shifts greater than 100 nm and their
emissions were higher than 500 nm. Molecule C, our most active molecule, had an emission at 620
nm, while the Stokes shift is 224 nm. Cell imaging experiments will be conducted on the various live
cell lines with different molecules.