2-Pyridone-based stilbazoles containing cyano and trifluoromethyl acceptors: Synthesis and fluorescence properties in solutions and in solid state

A novel simple and efficient stilbazole-based D-& pi;-A system containing cyano and trifluoromethyl acceptors was designed. The developed system demonstrated pronounced (fluoro)solvatochromic properties. The behavior of compound in solution was studied and three forms were identified, namely pyridone (PY), hydroxypyridine (HP), and anionic form (AN). Synthetic equivalents of these forms were prepared and their photophysical characteristics were investigated. It was shown that fluorescence of the stilbazole-based D-& pi;-A chromophore is originated exclusively from hydroxypyridine form, while the pyridone form makes a significant contribution to the absorption properties of the compound. Basing on the obtained 6-(4-(dimethylamino)styryl)-2-oxo-4-(trifluoromethyl)-1,2-dihydropyridine-3-carbonitrile a three position solid-state fluorescent acid-base switch was developed.