A label for immunofluorescence analysis based on europium complexes with fluorinated β-diketone of the carbazole series

A tetraketodiester of carbazole series containing methoxycarbonyl reactive groups separated from the chelating 1,3-dicarbonyl fragment by difluoromethylene spacers (CF2)4 was produced with the objective to develop new labels for the time-resolved immunofluorescence analysis. Complexes of this compound with Eu3+ ions are stable in aqueous solutions and demonstrate strong long-lasting (τ 550–570 μs) luminescence with major maxima of emission in the region of 615 nm and excitation in the region 380–390 nm, which distinguishes them from the majority of the available analogues. A conjugate of this compound with streptavidin was obtained with luminescence spectral characteristics allowing its application as a universal reagent for different schemes of biological microanalysis.