Zn(ii)-coordinated organic small molecule as a chiral fluorescent probe for discrimination and detection of tyrosine enantiomers

Abstract

Clamp-shaped chiral organic small molecules (COSM) are designed by linking one (1R,2R)-(+)-1,2-diphenyl-1,2-ethylenediamine molecule and two 5-methylsalicylic acid molecules via an amidation reaction. Aldehyde groups are introduced at positions ortho to the hydroxyl groups in the two 5-methylsalicylic acid units of the COSM via a Duff reaction. The COSM is then coordinated with Zn(II) to enhance its rigidity and strengthen its chirality. Imine bonds can be formed between the amino groups of tyrosine (Tyr) and the aldehyde groups of the COSM via a Schiff base reaction. These imine bonds play an important role in enhancing intramolecular charge transfer (ICT). Therefore, the Zn(II)-coordinated COSM can be used as a chiral fluorescent probe for discrimination and detection of Tyr enantiomers, and the limits of detection are 2.77 and 3.35 µM for D-Tyr and L-Tyr, respectively.