Aggregation Induced Emission Enhancement (AIEE) of Naphthalene- Appended Organic Moiety: An Al3+ Ion Selective Turn-On Fluorescent Probe

An example of an aggregation-induced emission enhancement (AIEE)-active new naphthalene appended Schiff base (H2L) as an Al3+ ion selective fluorescent sensor has been successfully designed and synthesized. H2L showed turn-on fluorescence at high concentration in DMF only, and at low concentration in DMF-H2O mixtures having high water content (more than 20%). But at very low concentration of H2L and in DMF/H2O solutions with low water fraction (f(w) <= 20%), the fluorescence was turned ON in presence of Al3+ ions, which helps to detect Al3+ ions as low as 4.9x10(-7) M with high selectivity in an DMF solution without any interference of other competitive metal ions. The fluorescence of H2L in different conditions and in solid state due to AIE effect has been established with the help of detailed spectroscopic studies, dynamic light scattering (DLS), scanning electron microscope (SEM), life time using time-resolved photoluminescence and optical fluorescence microscope. The experimentally observed H-type aggregation nature of the probe H2L has also been supported by the theoretical (DFT studies and TDDFT) studies. This probe (H2L) has also been employed for on-site Al3+ ions detection in solid state.