A dipodal molecular probe for naked eye detection of trivalent cations (Al3+, Fe3+and Cr3+) in aqueous medium and its applications in real sample analysis and molecular logic gates.

Abstract

A simple and low cost multifunctional colorimetric receptor L has been designed, synthesized and characterized by 1H-NMR, IR spectroscopy, ESI-MS spectrometry and elemental analysis. The chemosensor L can selectively detect three biologically and environmentally important trivalent metal ions (Al3+, Fe3+and Cr3+) both visually and spectrophotometrically in CH3CN–H2O (1 : 1, v/v) solution in the presence of other biologically relevant metal ions. The Job's plot analyses indicate the 2 : 2 binding stereochemistry for Al3+, Fe3+ and Cr3+ ions with L, which was further confirmed by 1H-NMR and ESI-MS studies. The binding constant values were found to be 2.9 × 104 M−1 for Al3+, 1.079 × 105 M−1 for Fe3+ and 1.366 × 105 M−1 for Cr3+ respectively. The detections limits of the sensor for Al3+ (2.8 × 10−7 M), Fe3+ (1.9 × 10−7 M) and Cr3+ (2.5 × 10−7 M) are far below than the limit set by the World Health Organization (WHO) for drinking water. Moreover, colorimetric test kits for rapid detection of Al3+, Fe3+, and Cr3+ could be successively applied for all practical purposes, indicating its potential use in environmental samples. It has also been used in building molecular logic gates.