Photochromic and Ionochromic Properties of N,N’- Cyclic Azomethine Imines

Photochromic 5-phenylpyrazolidin-3-one-basedazomethine imines containing 2-benzylidene 1, 2-(3- nitrobenzylidene) 2, 2-(4-nitrobenzylidene) 3, 2-((1H-imidazol-2-yl)methylene) 4, 2-(pyridin-2- ylmethylene) 5, 2-(quinolin-2-ylmethylene) 6 and 2-((8-hydroxyquinolin-2-yl)methylene) 7 substituents were synthesized. All the compounds exist in the ring-opened O forms. Under irradiation with light of 365 nm, compounds 1-7 undergo thermally reversible isomerization into ring-closed bicyclic diaziridine isomers C. Azomethine imines 4-6 exhibit properties of ion-active molecular “off-on” switches of fluorescence when interacting with F- or AcO- anions. Compound 7 represents bifunctional chemosensor demonstrating a colorimetric “naked-eye” effect for Ni2+cation and complete fluorescence quenching in the presence of H+, F– and CN– ions.