Development of a selective fluorescent ligand for aluminum ion having a 6-chloro-pyridazine moiety

•Developed a new fluorescence chemosensor for Al(III) ions, CPCH.•The CPCH–Al(III) complex fluoresces intensely in weak acidic media (pH 3.0).•Detection limit of Al(III) was approximately 200 nmol L−1.•Few metal ions disturb the fluorescence of CPCH–Al(III) complex.

A functional ligand, 6-chloro-N′-(2-hydroxybenzylidene)pyridazine-3-carbohydrazide (CPCH), was designed and synthesized, and metal ions that can induce fluorescence in CPCH were comprehensively screened by a batch method. CPCH showed intense fluorescence at 490 nm (ex. 394 nm) in the presence of Al(III) at weakly acidic pH values (2.0–6.0) because of the formation of a fluorescent CPCH–Al(III) complex. The binding ratio of CPCH to Al(III) was 3:1, as determined by the molar ratio method. The strongest fluorescence intensity of the CPCH–Al(III) complex was observed at pH 3.0, and the detection limit of Al(III) was approximately 200 nmol L−1.

Graphical abstractCPCH showed intense fluorescence at 490 nm (ex. 394 nm) in the presence of Al(III) over the weak acidic pH range (2.0–6.0), although CPCH itself generated no fluorescence.Figure optionsDownload full-size imageDownload as PowerPoint slide