Colorimetric detection of Al(III) ions based on triethylene glycol appended 8-propyloxy quinoline ester

A triethylene glycol modified quinoline ester (PQTEG) is synthesised, which acts as a colorimetric sensor for Al3+ ions with a detection limit of 8 × 10−7 M in acetonitrile/water (95:5, v/v) solvent system. A visible colour change from colourless to deep yellow was observed on binding of PQTEG with the metal ion. The unshared electron pairs of oxygen and nitrogen in triethylene glycol ester of quinoline provide a high binding affinity towards Al3+ and serves as the binding site. The metal binding was further confirmed from 1H NMR studies and IR spectroscopic studies.