Syntheses, Acidichromic and Hg2+-Sensing Properties of Novel Naphthalimide Derivatives

Two novel fluorescent naphthalimide-based sensors as ion sensor and acidichromic colorant are synthesized. This naphthalimide fluorophore is functionalized via a condensation reaction in which dithiodioxomonoaza-based crown-containing phenyl units are conjugated to the naphthalimide core as a trapper for detecting acids in the gas phase and heavy metal ions Hg²⁺. It shows a selective chromogenic behavior toward Hg²⁺ ion by changing the color of the solution. It also can be found that both on a solid PC (polycarbonate) film and in solution show acidichromism, i.e. a reversible color change upon alternatively exposing the films or solution to HCl and NH₃ gases, respectively. In this proposal, the designed sensors have been developed for the colorimetric and fluorescent determination by UV-Vis and fluorescence spectroscopy, and visual detection by the naked-eye. The visual detection provides a simple, rapid and sensitive method and was used for the detection of gaseous acids and Hg²⁺ ion in environmental applications.