Synthesis, Characterization, and Phosphate Anion Recognition Properties of Triethylene Glycol Bridged Oligourea Receptors

Two triethylene glycol bridged oligourea receptors R1 and R2 were synthesized and characterized by 1 H NMR, FT-IR, melting-point method and elemental analysis. The recognition properties of PO_4^3- were studied by naked eye recognition and UV-Vis spectroscopy. The Job’s plot analysis confirmed that the receptor R1 and PO_4^3- formed a complex at a molar ratio of 3:2 while the binding ratio of R2 to PO_4^3- was 1:1. The R1 recognized PO_4^3- with a complexing constant of 1.46 × 10 5 M –1 , and the complex constant of R2 recognizing PO_4^3- was 2.75 × 10 5 M –1 . In addition, the hydrogen bond between R1 and R2 with PO_4^3- was examined with the method of alcohol effect by adding competitive solvent ethanol to the DMSO system. Furthermore, the recognition of PO_4^3- by R1 and R2 was investigated through competitive measurements by adding other anions with the same concentration to the system. This study provides a simple and fast method for phosphate anion recognition.