Implementation of Zincke reaction in one-pot synthesis of switchable, Ag+ and Hg2+ sensing aza-merocyanines based on α-aminopyridin-3,5-dicarbonitrile moiety

Abstract

We report on the synthesis of new aza-merocyanines, which were synthesized via a modified Zincke reaction under one-pot conditions. These compounds exhibit a reversible color change from yellow to deep blue in solution upon exposure to trace bases. The blue form demonstrates some sensing ability for Ag+ and Hg2+ ions at concentrations above approximately 10−6 M, which is accompanied by a λmaxabs hypsochromic shift of about 20 nm and 100 nm, respectively. Furthermore, the presence of most other metal cations in solution does not affect this process. These results suggest that the synthesized aza-merocyanines hold promise for chemosensory applications.