Abstract
•A novel multidentate (N,S,O) donor ligand having pendant alkyl chain has been synthesized.•The ligand has been used for the effective stabilization of colloidal Ag-QDs.•These Ag-QDs can be stored for months under ambient conditions without aggregation.•Ag-QDs have been used as naked eye sensor for metal ion and anion at their very low concentration.•Ag-QDs have been used for the reduction of nitroarenes, an industrial pollutant, in water.
The present paper showed the role of ligand inthe effective stabilization of colloidal silver-quantum dots (Ag-QDs) and their applications for the colorimetric detection of metal ions/anions. Furthermore, the Ag-QDs have been explored to reduce nitroaromatics, industrial waste and pollutants. The donor atoms such as (N,S,O) present on ligands have been found to stabilize the Ag-QDs in the colloidal state effectively, and the pendant alkyl chain governs their uniform dispersion. The QDs (size ∼ 5 nm) are highly stable and can be kept in the colloidal state without aggregation for months under ambient conditions. The Ag-QDs showed naked-eye colorimetric sensing of Hg(II)/Cu(II) and I− ions selectively over other ions at very low concentrations. The colorimetric change has been attributed due to cation and anion-mediated aggregation of QDs. Furthermore, these QDs have also been found effective for reducing various nitroaromatics into valuable amines in a very short time and showed first-order kinetics with the calculated rate of 0.1352 min−1. The Hammett plot suggests that the reaction rate depends on the groups present at the para-position to the nitro group with a negative slope of − 1.291 which indicates that the reaction is proceedingviathe formation of a cationic intermediate. The results described in this paper will be the pioneer in the field of designing of new ligands for the effective stabilization of metal nanoparticles in the colloidal state without altering their activity.