Yellow-Green and Blue Fluorescent 1,8-Naphthalimide-Based Chemosensors for Metal Cations

Abstract

Two new 1,8-naphthalimides (NI), emitting yellow-green or blue fluorescence depending on the type of substituents at the C-4 position, have been synthesized and characterized. Their basic photophysical characteristics have been investigated in organic solvents of different polarities. Their ability to detect metal ions (Ag+, Cu2+, Zn2+ Ca2+, Mg2+, Ni2+, and Fe3+) has been studied in DMF solution. The amino (NI1) and alkoxy (NI2) functionalized 1,8-naphthalimides exhibit different optical and metal ion sensing properties attributable to the nature of the C-4 substituents. In addition, theoretical calculations based on the affordable but effective density functional theory (DFT) and time-dependent DFT (TDDFT) methods were performed in order to investigate the geometric and electronic structure of the title NI compounds.