Chiral cholesteric molecular tweezer artificial receptors 7a for the rapid detection of tryptophan and the chiral resolution of D-/-tryptophan

A cholesteric chiral molecular tweezer 7a was synthesized using deoxycholic acid as the raw material. The effects of various amino acids on the fluorescence spectra of molecular tweezer 7a were investigated. The chiral molecular tweezer 7a exhibited a specific recognition ability for tryptophan in Ethanol/Tris (1:1, v/v, pH 7.0) buffer, with a low detection limit of 0.17 μmol/L. In addition, the interference behavior of common metal cations and anions on compound 7a recognition of tryptophan was investigated. After eliminating the interference of anions and cations, a new method for the rapid determination of tryptophan in food samples was established. The recoveries of the method ranged from 97.53% to 107.35%, and the relative standard deviation ranged from 0.204% to 0.825%, according to the new method, the tryptophan content in infant milk powder, wheat flour and chicken meat were 2.029 mg/g, 1.844 mg/g and 3.306 mg/g, respectively, which were close to the reference value, indicating that the new method was accurate and reliable. Concurrently, molecular tweezer 7a was used for the chiral resolution of D-/L-tryptophan enantiomers. Baseline separation of D-/L-tryptophan enantiomers was realized by high performance liquid chromatography (HPLC) with a methanol solution (86.5/13.5, V/V) of cholesteric molecular tweezer 7a as the mobile phase.