Two multifunctional Mn(II) metal–organic frameworks: Synthesis, structures and applications as photocatalysis and luminescent sensor

Abstract

Two Mn(II) metal–organic frameworks, [Mn2L(1,10-phen)2]·DMF·0.5H2O (1) and [Mn(1,10-phen)(SO4)(H2O)2] (2) (H4L=bis-(3,5-dicarboxypheny1) terephthalamide) have been synthesized from Mn(II)/H4L system under different pH values conditions. The structures of the two MOFs were determined by single crystal X-ray diffraction analysis and characterized by elemental analysis, IR spectroscopy and thermogravimetric analysis. In compound 1, organic ligand (L4−) adopt six-dentate modes to link Mn(II) ions into 2D layer structure. For 2, only sulfate ion and 1,10-phen molecule link Mn(II) ions into 1D chain structure under higher pH value. The results demonstrate that pH values play an important role in the construction of the two MOFs. We also studied the photophysical properties and applications of the two MOFs as photocatalysts and fluorescence sensor materials. The photocatalysis results indicate that the two MOFs are stable and good candidates for degradation of RhB under UV light irradiation. And also, 1 has the higher photocatalytic activity than that of 2. In addition, the fluorescence sensing experiment demonstrates that 1 have significant selectivity in detection of aromatic amines and metal ions. All these results demonstrate that MOF-based materials can be used as multifunctional materials for photocatalytic degradation of organic dyes and detection of aromatic amines/or metal ions.