Eu(III)-organic complex as recyclable dual-functional luminescent sensor for simultaneous and quantitative sensing of 2,4,6-trinitrophenol and CrO₄ ²⁻ in aqueous solution

A novel metal-organic complex (MOC) {[Eu₂(HL)₂(H₂O)₄]·3H₂O}_n (1) (H₄L = 3,3′,5,5′-azoxybenzenetetracarboxylic acid) has been successfully constructed, which exhibits a fascinating 2D bilayer network with the 1D open channels and has excellent water, pH and thermal stabilities. Luminescence studies reveal that 1 can detect TNP and CrO₄ ²⁻ ions with high selectivity and sensitivity in aqueous solution, even if there are related interfering substances. And the mechanisms of luminescence recognitions are discussed on the basis of experiments and theoretical calculations. Furthermore, 1 shows excellent photostability and can be repeatedly used in the above two detection systems. Most importantly, 1 can detect TNP and CrO₄ ²⁻ concentration with a good recovery rate in practical application. Therefore, 1 should be a potential dual-functional luminescent sensor for reliable sensing of TNP and CrO₄ ²⁻ in the field.