Highly selective and sensitive metal-organic framework fluorescent probe for Cu2+ through rational design of binding sites

Eu3+ was successfully incorporated into two isostructural MOFs with different distributions of carboxyl groups, UiO-66-COOH and UiO-66-2COOH. Utilizing the specific binding site between two free carboxyl groups for efficiently capturing Cu2+, Eu3+@UiO-66-2COOH shows highly selective and sensitive luminescence quenching effect for Cu2+ in aqueous solution, while Eu3+@UiO-66-COOH with single free carboxyl group on the ligand possesses relatively poor performance. Meanwhile, such immobilization behavior of Cu2+ makes Eu3+ UiO-66-2COOH remarkably sensitive for Cu2+ at nano-molar concentration, superior to the majority of reported MOF sensors. (C) 2015 Elsevier Inc. All rights reserved.