Evaluation of Proto‐ and Metallofluorochromism Effects in Enamine Switches

The fluorochromism effects of a series of enaminitrile switches have been explored in response to protons or transition metal ions. Switches based on a 2‐pyridylacetonitrile group, linked to different aromatic entities via an enamine entity, were evaluated under acidic conditions or in the presence of Fe 2+ , Fe 3+ , Cu + , Cu 2+ , Zn 2+ , Ag + , Cd 2+ , or Tb 3+ . Two different absorptive/emissive patterns were found, attributed to charge transfer or chelation‐enhanced fluorescence effects, where selective metallofluorochromism could be recorded for Cu 2+ and Zn 2+ depending on the structures. The study provides comprehensive insights into how small structural modifications influence the responsive luminescence properties and highlights the roles of transition metals in molecular communication.