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

[Display omitted] • This paper presents the synthesis of a new class of "switchable" aza-merocyanines. • These compounds exhibit chemosensory properties towards Ag+ and Hg2+ ions. • The synthesis is simple and can be carried out under "One-Pot" conditions. 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 λ max abs 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. [ABSTRACT FROM AUTHOR]