2-Aminopyridine derivative as fluorescence ‘On–Off’ molecular switch for selective detection of Fe3+/Hg2+

2-Amino-6-methyl-4-phenyl-nicotinonitrile 1, a 2-aminopyridine-based fluorescent compound, was found to be a fluorescent chemosensor for the detection of Fe3+ and Hg2+ ions over a number of other metal ions. Compound 1 was synthesized in one step using a multicomponent reaction, and characterized using common spectroscopic tools. During Fe3+/Hg2+ sensing the compound 1 followed a ‘switch-off’ mechanism. Further, compound 1 could sense Fe3+ over Hg2+ by its distinct absorption and fluorescence quenching behaviors. 1:1 complex formation of 1 with Fe3+ and Hg2+ was clearly understood from Job’s plot. The present work brings additional evidence on the importance of multicomponent reactions which could lead to the development of fluorescence chemosensor in one step for the selective detection of biologically important metal ions.