An interpenetrated anionic In(III)-MOF for efficient adsorption/separation of organic dyes and selective sensing of Fe3+ ion and nitroaromatic compounds

A microporous indium-based metal-organic frameworks (MOFs), namely [(CH3)2NH2]2 [In2(H3L)2(OX)]·3DMF·2H2O (JOU-23) (H3L ​= ​terphenyl-3, 4′, 5-tricarboxylic acid; OX ​= ​oxalic acid), have been solvothermal synthesized and characterized. Single-crystal X-ray diffraction show that JOU-23 displays three-dimensional anionic framework with 2-fold interpenetrated nets and rare topology. Due to its anionic and porous framework, JOU-23 can be developed for effective absorbing and separating cationic organic dyes. Further studies reveal that both the charge and size of dye molecules would affect the dyes’ absorption and separation. In addition, JOU-23 dispersed in dimethyl formamide shows strong emission at about 364 ​nm. Thus, it was developed as an efficient fluorescent sensor for probing Fe3+ ions and nitroaromatic compounds. The detection limit of Fe3+ is as low as 2 ​× ​10−6 ​M (KSV ​= ​59,755 ​M−1), which is excellent in MOFs fluorescent probe. At the same time, JOU-23 shows widespread sensing performance to nitroaromatic compounds. Especially, the detection ability of JOU-23 for nitrobenzene (NB) is good. Although the NB concentration reaches only 4.175 ​× ​10−5 ​M, the quenching efficiency can achieve 86.4%. Further studies show that the quenching performance of JOU-23 is mainly attributed to the competition of excitation light absorption and the absorption of emission light by measured objects. These results indicate that JOU-23 can be applied as a multifunctional material for organic dyes adsorption/separation, Fe3+ ions detection, and nitroaromatic compounds sensing.