Excitation of One Fluorescent Probe at Two Different Wavelengths to Determine the Concentration and Enantiomeric Composition of Amino Acids

When a novel fluorescent probe made of BINOL and coumarin is excited at λ₁ = 365 nm in a neutral buffer solution, it shows fluorescence enhancement at 465 nm in the presence of an amino acid with a very small difference between the two enantiomers. When excited at λ₂ = 467 nm, it shows highly enantioselective fluorescence enhancement at 534 nm. This allows the determination of both concentration and enantiomeric composition of amino acids.