Wavelength specific aggregation induced emission in aqueous media permits selective detection of Ag⁺ and Hg²⁺ ions

A new 1,8-naphthalimide derivative (probe 1) adopts V-shaped structure, emits fluorescence and displays the Mie effect and aggregation-induced emission (AIE). Selective interactions of thiophilic Ag⁺ and Hg²⁺ ions (10 µM) with 1 (10 µM) resulted in AIEs at 499 and 521 nm, respectively. Both Ag⁺ and Hg²⁺ induce the formation of 1:2 complexes with 1, leading to the formation of AIE active aggregates with an average size of 423 and 198 nm, respectively. The formation of crystalline needles with Ag⁺ and spherical aggregates with Hg²⁺ results in wavelength specific AIE that permits the naked-eye and fluorometric detection of Ag⁺ and Hg²⁺ ions. Probe 1 shows excellent selectivity toward Ag⁺ and Hg²⁺ among various metal ions, therefore, 1 is suitable for the selective and quantitative detection of Ag⁺ and Hg²⁺ ions. Job plots are used for the determination of the stoichiometry of the complexes formed. It is evident from the fluorescence images of probe 1 in Rhizoctonia oryzae mycelia cells that they can be employed as potential candidates for in-vitro bioimaging.