An Eu3+ post-functionalized nanosized metal–organic framework for cation exchange-based Fe3+-sensing in an aqueous environment

Abstract

A novel strategy was demonstrated to fabricate a luminescent lanthanide functionalized MOF by encapsulating Eu³⁺ cations in the pores of MIL-53–COOH (Al) nanocrystals. The Eu³⁺ incorporated sample shows excellent luminescence and good fluorescence stability in water due to the sensitization and protection provided by the parented framework. Subsequently, Eu³⁺ incorporated nanocrystals were developed as a highly selective and sensitive probe for detection of Fe³⁺ in aqueous solutions. In addition, the possible sensing mechanism based on cation exchange between Fe³⁺ and the framework Al³⁺ in MIL-53–COOH (Al) was discussed in detail. This is the first example for detecting Fe³⁺ in aqueous solutions based on a lanthanide functionalized nanoscale MOF. The good fluorescence stability in an aqueous environment, the low detection limit and the broad linear range, together with the nanoscale nature of this probe suggest it has potential for intracellular sensing and imaging of Fe³⁺.