Effective recognition of multiple anions by an azobenzene Al 3+ system

Abstract

A ready-to-use multifunctional coordinative system, 2,2 -dihydroxyazobenzene aluminum (III) (DHABAl 3+), was created to recognize several anions effectively through three channels, namely colorimetric detection, UV-Vis spectroscopy, and fluorescence spectroscopy. Under naked eye visualization, the H2PO − 4 can be readily distinguished from the other anions by the DHAB Al 3+ system through a change in color from reddish-orange to light yellow. H2PO − 4 was qualitatively detected by using UV-Vis and fluorescence spectra. Differentiating SO2− 3 , HPO2− 4 , and HCO − 3 anions colorimetrically is difficult; thus, CO2− 3 , SO2− 3 , HPO2− 4 , and HCO − 3 were discriminated by adopting distinct changes in the UV-Vis spectra. CO2− 3 , HPO2− 4 , and HCO − 3 were accurately quantified using fluorescence spectra. The DHABAl 3+ system responded to H2PO − 4 and CO2− 3 via a sensing mechanism based on a displacement approach. By contrast, the system responded to SO2− 3 , HPO2− 4 , and HCO − 3 based on a binding site signaling subunit approach. The DHABAl 3+ system can determine the concentration ranges of H2PO − 4 with the naked eye and quantify CO2− 3 , SO2− 3 , HPO2− 4 , and HCO − 3 through UV-Vis spectra