2-Aza-1,3-butadiene Derivatives Featuring an Anthracene or Pyrene Unit:  Highly Selective Colorimetric and Fluorescent Signaling of Cu²⁺ Cation

A new probe based on an anthryl derivative bearing an azadiene side chain selectively senses Cu²⁺ in acetonitrile through two different channels:  the yellow-to-orange color change and a remarkable enhancement of the fluorescence, whereas the pyrenyl analogous behaves as a fluorescent sensor for Cu²⁺ and Hg²⁺ in aqueous environment.