Microwave-Assisted Synthesis of Thiophene Fluorophores, Labeling and Multilabeling of Monoclonal Antibodies, and Long Lasting Staining of Fixed Cells

We report the expedient microwave-assisted synthesis of thiophene based 4-sulfo-2,3,5,6,-tetrafluorophenyl esters whose molecular structure was engineered to achieve blue to red bright fluorescence. The reactivity toward monoclonal antibodies of the newly synthesized fluorophores was analyzed in comparison with that of the corresponding N-succinimidyl esters. Single-fluorophore and multiple-fluorophore labeled antibodies were easily prepared with both types of esters. Multiple-fluorophore labeling with blue and orange emitting fluorophores resulted in white fluorescent antibodies. Thiophene based fluorophores displayed unprecedented fluorescence stability in immunostaining experiments. First-principles TD-DFT theoretical calculations helped us to interpret the behavior of fluorescence emission in different environments.