A retrievable and highly selective fluorescent probe for monitoring dihydrogen phosphate ions based on a naphthalimide framework

• The fluorescence change occurs via reversible formation-separation of complex.
• The sensor had a high selectivity for H2PO4-.
• DFT calculations were used to verify the configuration of complex.

A novel selective fluorescent chemosensor based on naphthalimide derivatives (AN-SB) was synthesized and characterized. Once combined with Cu2+, compound AN-SB could give rise to a visible yellow to orange color change and fluorescence quenching, while other metal ions showed subtle disturbance. The complex (AN-SB–Cu2+) formed by Cu2+ and AN-SB displayed high specificity for H2PO4-. Among the various anions, only H2PO4- induced the revival of color and fluorescence of AN-SB, resulting in “off–on” type sensing of H2PO4- anion. The signal transduction occured via reversible formation–separation of complex AN-SB–Cu2+, however, slight changes were observed in the presence of other anions.

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