Highly selective C2H2 and CO2 capture based on two new ZnII-MOFs and fluorescence sensing of two doped MOFs with EuIII

Abstract

Two structurally similar columnar Zn^II-MOFs {[Zn₈L₄(TZ)₄·0.5H₂O]·4[Me₂NH₂]·6DMF·4H₂O}_n (Zn-MOF1) and {[Zn₄L₂(MT)₂·H₂O]·2[Me₂NH₂]·4DMF·4H₂O}_n (Zn-MOF2) were synthesized with irregular ligands, 2,2′-(pyridine-2,6-diyl) diterephthalic acid (H₄L), 1,2,4-triazolium (TZ) and 1H-1,2,4-triazole-3-thiol (MT). Structural studies showed that both Zn^II-MOFs had a similar 3D framework constructed with multiple SBUs and displayed an unusual (3,4,6)-connection topology. Furthermore, both Zn^II-MOFs have high performance in gas adsorption and separation. The separation ratios of C₂H₂/CH₄ and CO₂/CH₄ of Zn-MOF1 were 15.1 and 6.8, respectively, and those of Zn-MOF2 were 14.6 and 6.5, respectively. Moreover, Eu@Zn-MOF1 and Eu@Zn-MOF2 were successfully obtained by adding Eu³⁺ ions to the synthesis system. After a series of fluorescence tests, these two MOFs were found to have good fluorescence performance, and showed high selectivity and sensitivity to Fe³⁺ ions in aqueous solution with a low detection limit.