Synthesis of cyclodextrin functionalized photoluminescent metal nanoclusters for chemoselective Fe3+ ion detection in aqueous medium and its applications of paper sensors and cell imaging

Abstract

Owing to the potential uses of metal nanoclusters for chemistry and material science applications, their rational design has attracted the attention of researchers. While copper nanoclusters present economical and practical advantages, few developments have been made toward their synthesis and applications. In this study, photoluminescent supramolecular cyclodextrin-functionalized copper nanoclusters (CDNCs) are used as chemosensors for the detection of Fe3+ in aqueous solutions. The as-synthesized CDNCs possess many attractive characteristics, including intense green emission under ambient conditions, colloidal stability, large effective Stokes shift, and high quantum yield (37.2%). Furthermore, CDNCs exhibit higher selectivity and sensitivity for Fe3+ than for other cations and anions. This was demonstrated by the appearance of the new absorption peak at 390 nm in their ultraviolet–visible spectrum and the increase in the intensity of the 490 nm photoluminescence peak. The photoluminescence of the as-synthesized CDNCs increased in the presence of 20 equiv. Fe3+, and the CDNCs chemosensor became reversible after the addition of 100 equiv. ethylenediaminetetraacetic acid. The highest concentration of iron in drinking water allowed by the United States Environmental Protection Agency is 5.37 × 10−6 M, and therefore, the limit of detection and limit of quantification of CDNCs for Fe3+ (1.33 × 10−7 M and 4.55 × 10−7 M) and its rapid response toward Fe3+ (<2 min) render it effective for monitoring the concentration of iron in drinking water. The potential uses of the CDNCs-Fe3+ complex for paper sensors and cell imaging are successfully demonstrated.