Synthesis of fluorescent di-dansyl substituted ethoxy compound: A selective sensor for antimony and thallium metals detection

Abstract

Fluorescence assays have been widely engaged to assess the affinity of metallic ions. Dansyl chloride or 5-(dimethyl amino)-naphthalene-1-sulfonyl chloride is considered to be the reagent having potential to react with amino groups to yield stable sulfonamide adducts. A fluorescent sensor associated with crown ether moiety could have a potential to be developed as metal ions radar; cations, anions and other biological moieties. This can be further employed to observe relevant biotic processes. The reaction of dansyl sulfonyl chloride with di-ethoxy amine 1 chain in presence of potassium carbonate base resulted in a formation of compound 2. No change was observed on addition of aliquots of anions with compound 2. However, cation binding studies was performed using the series of metallic cations of constant concentration and its influence on a series of cations has been monitored using fluorescence spectrometry. This has been recorded that highest quenching effect was observed for antimony (Sb) and thallium (Tl) while other anions and cations were having no effect. The fluorescent compound 2 was further confirmed with proton-nuclear magnetic resonance (1H NMR) spectroscopy, 13C NMR spectroscopy and ultra violet spectroscopy. It has been concluded that compound 2 is very much selective for the detection of toxic metals like antimony (Sb) and thallium (Tl) even at parts per billion (ppb) levels. This study could be considered as a contemporary development in design and applications of fluorescent investigations containing crown ethers.