Synthesis and application of N-hydroxysuccinimidyl rhodamine B ester as an amine-reactive fluorescent probe

A fluorescent probe (RB–S) containing the N-hydroxysuccinimidyl ester in 2 position was prepared from rhodamine B (RB) by one-step condensation reaction. The reactivity of the fluorescent probe with glycine was studied and the products were identified by LC–MS analysis. The excessive equivalent of the RB–S was hydrolyzed to the corresponding carboxylic acids (RB). UV/vis and fluorescence spectra of the fluorescent probe (RB–S), the labeled derivative (RB–Gly) and the hydrolysate (RB) were also studied. Fluorescence and absorption spectra appear as mirror images. The solvent effect on the spectra of the glycine derivative (RB–Gly) was investigated in methanol/water solution.