Enantioselective Fluorescent Sensors for Chiral Alpha-Hydroxycarboxylic Acids, Amino Acid derivatives and Diamines

A series of enantioselective fluorescent sensors based on chiral 1,1'-bi-2-naphathol (BINOL) was designed and developed for the recognition of chiral alpha-hydroxycarboxylic acids, amino acid derivatives and diamines.
A new concept with the use of a pseudoenantiomeric fluorescent sensor pair for enantioselective fluorescent sensing was introduced. A pseudoenantiomeric fluorescent sensor pair is composed of two fluorescent sensors that emit at different wavelengths and have the opposite enantioselectivity. When a 1:1 mixture of BINOL-based and H8BINOL-based sensors are used to interact with mandelic acid, the sum and difference of the fluorescence intensity at the two different emission signals of the two sensors allow the determination of both the concentration and the enantiomeric composition of a mandelic acid sample by a single fluorescence measurement.
A BINOL-trifluoroacetyl compound is discovered to exhibit high sensitivity at one emission wavelength and high enantioselectivity at another when treated with a chiral diamine. By using this single fluorescent sensor it was demonstrated for the first time that both the concentration and enantiomeric composition of a chiral substrate can be determined simultaneously with one fluorescent measurement.
These discoveries represent important progress in the field of enantioselective fluorescent sensors and have fundamental significance for the potential application of fluorescence in chiral catalyst screening.