Highly Sensitive Dansyl-Based Chemosensor for Detection of Cu²⁺ in Aqueous Solution and Zebrafish

A new dansyl-based chemosensor (2-(4-((5-(dimethylamino)­naphthalen-1-yl)­sulfonyl)­piperazin-1-yl)-N-(quinolin-8-yl)­acetamide) (DC) for detecting Cu²⁺ was synthesized and characterized. DC showed great selectivity to Cu²⁺ by a fluorescent “on–off” detection method. Job plot, ESI-mass spectroscopy, and ¹H NMR titration suggested a 1 to 1 binding mode between DC and Cu²⁺. The detection limit was determined to be 43 nM, which is greatly below the WHO guidelines. In addition, DC can be applied to real samples and zebrafish imaging. The fluorescence quenching mechanism was proposed as the enhancement of intramolecular charge transfer with calculations.