A Turn “ON” bis-napthalimide-based Chemosensor for Detection of Al3+ Ions and Nerve Agent

Abstract

A bis-napthalimide based chemosensor was designed and synthesized for sensing anions and metal ions. The studies of UV-visible spectra of compound 6 revealed two absorption bands at 325 nm and 355 nm in CH3OH solution. In addition, a new absorption band at 335 nm was observed after adding DCP. Similarly, compound 6 displayed two absorption bands at 338 nm and 408 nm after adding Al 3+ ions. In the CH3OH solution, the fluorescence of compound 6 is in the quenched state. However, the fluorescence intensity increased with the addition of the DCP and Al 3+ ions, with the emission maxima occurring at 371 nm for DCP ions and 450 nm for Al 3+ ions. The binding constant for compound 6 towards DCP was 5.2 × 10 4 M -1 and for Al 3+ ions is 2.5 × 10 4 M -1 . With the addition of the DCP and Al 3+ ions, the turn-on fluorescence was observed with detection limits of 8.5 nM and 22 nM, respectively. Compound 6 showed high selectivity and sensitivity towards DCP and Al 3+ ions over the other ions. As a result, the synthesized bis-naphthalimide chemosensor is a "Switch-ON" fluorescence-type chemosensor.