A dipodal molecular probe for naked eye detection of trivalent cations (Al(3+), Fe(3+)and Cr(3+)) in aqueous medium and its applications in real sample analysis and molecular logic gates

A simple and low cost multifunctional colorimetric receptor L has been designed, synthesized and characterized by (1)H-NMR, IR spectroscopy, ESI-MS spectrometry and elemental analysis. The chemosensor L can selectively detect three biologically and environmentally important trivalent metal ions (Al(3+), Fe(3+)and Cr(3+)) both visually and spectrophotometrically in CH(3)CN–H(2)O (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 Al(3+), Fe(3+) and Cr(3+) ions with L, which was further confirmed by (1)H-NMR and ESI-MS studies. The binding constant values were found to be 2.9 × 10(4) M(−1) for Al(3+), 1.079 × 10(5) M(−1) for Fe(3+) and 1.366 × 10(5) M(−1) for Cr(3+) respectively. The detections limits of the sensor for Al(3+) (2.8 × 10(−7) M), Fe(3+) (1.9 × 10(−7) M) and Cr(3+) (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 Al(3+), Fe(3+), and Cr(3+) 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.