Highly sensitive and selective fluorescence detection of copper (II) ion based on multi-ligand metal chelation

• A novel dansyl-based fluorescent probe for divalent copper ion was synthesized with high quantum yields.
• The fluorescent probe is photostable and pH insensitive.
• The probe shows high selectivity and sensitivity towards copper (II) ion over other biological relevant metal ions.
• The fluorescent probe has the potential to detect copper (II) ion in real sample.

A fluorescent probe was synthesized and demonstrated to be highly selective and sensitive in the reaction with copper (II) ion, generating a large variation of the fluorescence intensity in a dose–response manner. The probe contains a dansyl moiety as fluorophore and a multidentate ligand for copper (II) ion recognition. The reaction of the molecular probe with copper (II) ion proceeds rapidly and irreversibly in a 1 to 1 stoichiometric way, leading to the production of stable copper (II) complex, which subsequently results in the quenching of fluorescence. The detection limit for copper (II) ion was measured to be about 2 ppb. It was also shown that the probe has high selectivity for copper (II) ion and good anti-interference ability against other transition metal ions. The herein reported very simple and reliable fluorescence probe could be employed for copper (II) ion detection in many aspects.

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