A luminescent Cd(ii) coordination polymer as a multi-responsive fluorescent sensor for Zn 2+ , Fe 3+ and Cr 2 O 7 2- in water with fluorescence enhancement or quenching.

A luminescent Cd(ii) coordination polymer, namely {[Cd(btic)(phen)]·0.5H ₂ O} _n (CP-1) (H ₂ btic = 5-(2-benzothiazolyl)isophthalic acid, phen = 1,10-phenanthroline), was constructed through the mixed-ligand method under solvothermal conditions. CP-1 manifests a chain structure decorated with uncoordinated Lewis basic N and S donors. CP-1 exhibits high sensing towards Zn ²⁺ , Fe ³⁺ and Cr ₂ O ₇ ^2- ions with fluorescence enhancement or quenching. CP-1 exhibited a fluorescence enhancement for Zn ²⁺ ions through weak binding to S and N atoms, and a fluorescence quenching for Fe ³⁺ and Cr ₂ O ₇ ^2- ions by an energy transfer process. The binding constants were calculated as 1.812 × 10 ⁴ mol ^-1 for Zn ²⁺ , 4.959 × 10 ⁴ mol ^-1 for Fe ³⁺ and 1.793 × 10 ⁴ mol ^-1 for Cr ₂ O ₇ ^2- . This study shows CP-1 as a rare multi-responsive sensor material for the efficient detection of Zn ²⁺ , Fe ³⁺ and Cr ₂ O ₇ ^2- ions.
Competing Interests: There are no conflicts to declare.
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