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.