Fluoride ion activated CO₂ sensing using sol-gel system

CO₂ detection has drawn a lot of attention due to its important role in the environment and in medical diagnosis. Two amino substituted naphthalimides are reported as new anion-induced CO₂ selective chemosensors. The new naphthalimides contain either a hydrazinecarbothiourea or a hydrazinecarboxylate group which served as an anion recognition site. The addition of F⁻ induced a distinct color change and a fluorescent quenching effect, which was revived by subsequent addition of CO₂. The naphthalimide bearing a hydrazinecarboxylate group also served as an organo gelator, which showed a unique sol-gel transition as well as color/fluorescent changes with F⁻ and CO₂.