A supramolecular sensor system to detect amino acids with different carboxyl groups

Abstract

A supramolecular sensor was designed and synthesized for the detection of different amino acids. This sensor with formylated resorcin[4]arene structure was achieved by the reaction of resorcin[4]arene through Duff reaction. It has observed that amino acids with different amount and position of carboxyl groups show different binding constants on ultraviolet-visible (UV–vis) spectra. There are two reasons to explain this signal change. Firstly, the four aldehyde in the sensor was taken to react with the amino group of amino acids. A product with four keto-enamines were obtained and intramolecular hydrogen bonds were formed to stabilize the product. Secondly, the carbonyls in amino acids also formed hydrogen bonds with the hydroxyls. The structure of the sensor and the mechanism of the sensing process was carried out by NMR, X-ray diffraction and Electrospray ionization (ESI) mass spectra. This finding may be very useful to explore the host-guest chemistry and develop sensors for different amino acids.