Fluorescent detection of amidinium-carboxylate and amidinium formation using anthracene-based diamidine: an application for the analysis of dicarboxylic acid binding

An anthracene-based diamidine (1) ‘turn-on’ fluorescent probe for the detection of dicarboxylic acids has been designed and synthesized. The fluorescence spectra of the diamidine 1 with carboxylic acids that showed two different fluorescence bands, which corresponded to the amidinium-carboxylate (λ_em=430-440 nm), and amidinium (λ_em=460-470 nm as a broad band) formation, were confirmed by DOSY NMR and TD-DFT calculations. These different fluorescence bands showed the binding mode of carboxylic acids and the stability of formed complexes toward diamidine 1. The fluorescent detection of amidinium-carboxylate formation using diamidine 1 was applicable to the detection of α,ω-dicarboxylic acids (C₆-C₁₃) and succeeded in the detection of α,ω-dicarboxylic acid (adipic acid) in human urine.