Highly Selective Aminopyrazine‐Based Colorimetric Probe for “Naked‐Eye” Detection of Al3+: Experimental, Computational Studies and Applications in Molecular Logic Circuits

Abstract

AbstractA simple colorimetric probe NPA was synthesized using 2‐aminopyrazine and 2‐hydroxynaphthaldehyde. The probe had demonstrated quick response and high selectivity toward Al3+ in the presence of other interfering metal ions. A notable color change from bright yellow to colorless was noticed on addition of aqueou solutions of Al3+ to NPA in CH3CN‐H2O (1 : 1, v/v) in physiological pH range. 1 : 1 stoichiometry in NPA‐Al3+ complex was confirmed from Job's plot and mass spectrometry. Complexation of Al3+ with the probe molecule was also confirmed using 1H NMR spectroscopy. A theoretical model structure of the complex was proposed based on density functional theory (DFT). Disruption of conjugation in the naphthalene moiety and enhancement in intramolecular charge transfer (ICT) in the complex had decreased the absorbance of NPA. Paper strip of NPA was used for fast “on‐site” detection of Al3+ without using any spectroscopic instrument. The probe was found reusable for several times. The probe can also be used for the development of molecular logic gate for the detection of Al3+.