A micrometer-sized europium(<scp>iii</scp>)–organic framework for selective sensing of the Cr₂O₇²⁻ anion and picric acid in water systems

Abstract

A micrometer-sized europium(iii)-organic framework with asymmetric binuclear metal subunits extended by 4,5-dichlorophthalaten (DCPA), [Eu₂(H₂O)(DCPA)₃]_n, was easily obtained using a reverse microemulsion method. The framework exhibits good dispersibility, excellent thermal and environmental stability and easy regeneration ability. More importantly, the complex displays strong red emission and can selectively and sensitively detect both inorganic Cr₂O₇^2- anions (K_sv = 8.7 × 10³ M^-1) and organic picric acid contaminants (K_sv = 1.07 × 10⁴ M^-1) in water systems through fluorescence quenching. A luminescent film of 1 was further prepared and successfully used to detect the Cr₂O₇^2- anion in an aqueous system. These interesting results indicate that the well-dispersed europium(iii)-organic framework can serve as a promising dual-responsive luminescent sensor for environmental pollutant monitoring.