A new azo-azomethine chemosensor containing active phenolic sites, H2L, has been designed and synthesized for rapid detection of inorganic fluoride over the other anions, such as Clˉ, Brˉ, Iˉ, AcOˉ, H2PO4ˉ, NO3ˉ, N3ˉ in DMSO/water (90/10) media. The 1H NMR titration revealed that the colorimetric response was considered to be the direct consequence of hydrogen-bond formation between phenolic gr...