A chromogenic anthraimidazoldione probe for ratiometric analysis of Hg2+ exclusively at mesoscopic interface: Screening of real-life biological samples

Abstract

In the present work, we have synthesized amphiphilic anthraimidazoldione derivative that can form nanoassembly in the aqueous medium. The π-conjugated backbone with facile intramolecular charge transfer from the substituted aryl residue to anthraquinone unit attributed to the profound orange color. Despite having the metal ion chelating aminoethyl acetamide unit, the compound showed no interaction with metal ions in the aqueous medium. However, a highly selective color-changing response, from orange to yellow (Δλ ∼52 nm), was observed upon addition of Hg2+ ion at micellar interface. Also, a turn-on fluorescence response (∼5.2-fold) was witnessed with Hg2+. It was observed that in addition to hydrophobic microenviroment, the orientation of molecules at water-surfactant interface also responsible for the chromogenic response towards Hg2+ ion. The mechanistic investigation indicated that Hg2+ ion coordinates with the aminoethyl acetamide unit, resulting restriction in the extent of intramolecular charge transfer. Considering such highly ratiometric response, the present system has been employed for analysis of Hg2+ ion in diluted urine and blood serum samples. The high recovery values (95.4 % to 104.3 %) with relatively low standard deviations (< 4.2 %) indicated that the present system is fairly successful in screening of complex real-life samples. Finally, we have designed low-cost, reusable, chemically modified paper strips for on-location, rapid analysis of mercury ions.