A multifunctional Zr(iv)-based metal–organic framework for highly efficient elimination of Cr(vi) from the aqueous phase

Abstract

A highly stable luminescent Zr(IV)-MOF, [Zr₆O₄(OH)₈(H₂O)₄(TCPP)₄]·9DMF·3.5H₂O (JLU-MOF60, H₄TCPP = 2,3,5,6-tetrakis(4-carboxyphenyl)pyrazine, DMF = N,N-dimethylformamide) was successfully prepared. JLU-MOF60 with the AIE effect and high porosity consists of 8-c Zr₆ clusters and 4-c ligands with an sqc topology. Interestingly, it exhibits remarkable chemical stability in water over extensive pH values varying from 0 to 11. Due to its outstanding water stability and Zr-bonded hydroxides in the framework, JLU-MOF60 shows a high capture capability (149 mg g⁻¹) and rapid adsorption rate (38 mg g⁻¹ min⁻¹) for Cr₂O₇²⁻ in water. Moreover, benefiting from the AIE effect of the H₄TCPP ligand, JLU-MOF60 can not only sensitively and selectively detect Cr₂O₇²⁻, but also effectively photo-reduce Cr(VI) to Cr(III) in the aqueous phase. It is worth mentioning that the K_SV value of JLU-MOF60 for detecting Cr₂O₇²⁻ is as high as 5.91 × 10⁴ M⁻¹, and the detection limit is as low as 0.38 μM. Simultaneously, the κ value of the photocatalytic reaction can reach up to 0.058 min⁻¹. Accordingly, JLU-MOF60 can be regarded as a multifunctional material to efficiently eliminate Cr₂O₇²⁻ from the aqueous phase.