Visualized fabric discoloration of bi-heterocyclic hydrazone dyes

Fabric discoloration has been firstly observed for a family of full heterocyclic hydrazone dyes with 2-amino-3-cyano-4-chloro-5-formylthiophene and pyridine-2,6-dione components, which is believed to originate from the proton transfer between azo and hydrazone tautomerism induced by different fabric microenvironments.238