Detection and Sorption of Heavy Metal Ions in Aqueous Media by a Fluorescent Zr(IV) Metal-Organic Framework Functionalized with2-Picolylamine Receptor Groups br

Increasing global environmental pollution due toheavy metal ions raises the importance of research on newmultifunctional materials for simultaneous detection and removal ofthese contaminants from water resources. In this study, we report amicroporous 8-connected Zr4+metal-organic framework (MOF)based on a terephthalate ligand decorated with a chelating 2-picolylamine side group (dMOR-2), which shows highly efficientfluorescence sensing and sorption of heavy metal cations. Wedemonstrate by detailedfluorescence studies the ability of a water-dispersible composite ofdMOR-2with polyvinylpyrrolidone forreal-time detection of Cu2+,Pb2+, and Hg2+in aqueous media. Thelimits of detection were found to be below 2 ppb for these species, while the system's performance is not affected by the presence ofother potentially competitive ions. In addition, sorption studies showed that a composite ofdMOR-2with calcium alginate (dMOR-2@CaA) is an excellent sorbent for Pb2+and Cu2+ions with capacities of 376 +/- 15 and 117 +/- 4 mg per gram ofdMOR-2@CaA,respectively, while displaying the capability for simultaneous removal of various heavy metal ions in low initial concentrations and inthe presence of large excesses of other cationic species. Structural and spectroscopic studies with model ligands analogous to ourmaterial's receptor unit showed chelation to the 2-picolylamine moiety to be the main binding mode of metal ions todMOR-2.Overall,dMOR-2is shown to represent a rare example of a MOF, which combines sensitivefluorescence detection and highsorption capacity for heavy metal ions