Dansyl derivative turn off fluorescent probe for Al3+: Experimental and computational study in aqueous medium

A dansyl derivative sensor termed as o-PDDS (N-(2-aminophenyl)-5-(dimethilamino)-1-naphtalenesulfonic amide) was prepared and studied for detection of Al3+ ions in aqueous medium. The synthesized sensor was characterized and confirmed by NMR, UV-Visible and fluorescence studies. The performance of the sensor against different inorganic ions was evaluated with greater sensitivity for aluminum. Then a computational study was performed to propose the stoichiometry ratio between Al(III)-(o-PDDS). The o-PDDS sensor showed good linear responses toward Al3+ ions at concentrations between 0.3-133.3 mu M and limit of detection of 1.9 mu M. The binding constant between Al3+ ions and o-PDDS has been determined by using both the Benesi-Hildebrand and Stern-Volmer equation, and the results indicated a static mechanism of quenching and high sensitivity of the oPDDS to Al3+ ion. In line with experimental absorption and emission spectra, density functional theory calculations suggest a stoichiometry ratio between the o-PDDS and Al3+ of 1:1 in the complex Al(III)-(o-PDDS). Furthermore, the interference study and real sample assays of tap, distilled, and dialysis water exhibited satisfying results, which provides the possibility of developing a simple and efficient aluminum sensor for field use.