A new Zn–Na bimetallic metal–organic framework with dual functions for fluorescent detection of Fe3+ and MnO4−, and CO2 fixation

Abstract

The development of multifunctional materials for dual applications—as chemical sensors for various pollutants and efficient catalysts for CO₂ conversion is of great importance for public health. In pursuit of this goal, we designed and synthesized a new three-dimensional bimetallic MOF {(Me₂NH₂)·[ZnNa(btda)₂]·DMF}_n (1) (H₂btda = 2,5-benzo[b]thiophenedicarboxylic acid) based on the aromatic dicarboxylate ligand H₂btda. The structural characterizations show that 1 has a three-dimensional anionic network structure constructed by Zn–Na-carboxylate chains with btda²⁻ linkers which exhibits good thermal stability up to ca. 275 °C. Luminescent sensing experiments suggest that 1 exhibits high selectivity and high sensitivity in the detection of both Fe³⁺ and MnO₄⁻. The extracted Stern-Volmer quenching constants and the limits of detection are, respectively, 2.65 × 10⁴ M⁻¹ and 6.65 × 10⁻⁷ mol L⁻¹ for Fe³⁺, 3.2 × 10³ M⁻¹ and 5.35 × 10⁻⁶ mol L⁻¹ for MnO₄⁻. The catalytic investigation indicates 1 is also an effective heterogeneous catalyst for the cycloaddition reactions of CO₂ and single-substituted epoxides to produce cyclic carbonates.