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Anionic metal–organic frameworks (MOFs) with a negatively charged framework have attracted extensive attention for their potential applications in organic dye adsorption and separation. However, the rational synthesis of anionic MOFs with tunable channel size is still difficult. In this work, two pillar-layered MOFs, namely [(CH3)2NH2]2[Zn4(BTC)2TCPB]·3DMF·H2O (JOU-44) and [(CH3)2NH2]2[Zn4(BPTC)2TCPB]·12DMF·6H2O (JOU-45), were solvothermally synthesized by using a reticular chemistry strategy (H3BTC = 1,3,5-benzenetricarboxylic acid; H3BPTC = [1,1′-biphenyl]-3,4′,5-tricarboxylic acid; H4TCPB = 1,2,4,5-tetrakis(4-carboxyphenyl)benzene). Structural analyses show that JOU-44 and JOU-45 show an isoreticular three-dimensional anionic framework based on [Zn2(COO−)5]− clusters. It should be noted that the pillar-layered framework of JOU-44 is expanded by adjusting the length of the ligands in the layer part, which is different from the pillar extension method reported in the literature. Due to its anionic and highly porous framework, JOU-44 was exploited for adsorption and chromatographic separation of organic dyes. In addition, JOU-44 was also developed as an antenna to selectively sensitize EuIII ions. This work provides a new clue for constructing pillar-layered MOFs with an extensible structure, as well as a new way to extend the applications of MOFs in separation and fluorescence. [ABSTRACT FROM AUTHOR]

A newly pyrene functionalized zinc(II)-MOF was solvothermal synthesized and developed for fluorescence sensing of nitroaromatic compounds due to its good photoluminescence properties. [Display omitted] In this work, a zinc(II)-based metal–organic framework, namely [Zn 2 (TBAPy)(H 2 O)(DMF)]·4DMF·2H 2 O (JOU-34) (TBAPy = 1,3,6,8-tetrakis (p-benzoic acid) pyrene; DMF = N,N'-Dimethylformamide), has been solvothermally synthesized and characterized. Single-crystal X-ray diffraction shows that JOU-34 displays three-dimensional microporous framework with rare topology. Due to the introduction of pyrene groups, JOU-34 shows strong fluorescent emission cantered at about 470 nm. Furthermore, it shows a good fluorescence sensing performance toward nitroaromatic compounds, especially nitrobenzene (NB). Although the NB concentration was only 8.33 × 10−4 M, the quenching efficiency can reach 89 %. Further studies show that the quenching effect of JOU-34 in the presence of nitroaromatics may be attributed to the fluorescence resonant energy transfer and electron transfer between nitroaromatics and JOU-34. These results indicate that JOU-34 can be applied as a functional material for nitroaromatics detection. [ABSTRACT FROM AUTHOR]

Although iron-based metal-organic frameworks (Fe-MOFs) have displayed the photocatalytic activity, there is still abundant room for improving their photocatalytic performance through tuning the structures. In this work, four novel iron-based metal-organic frameworks (Fe-MOFs) were successfully synthesized via ligand modulation for better photocatalytic Cr(VI) reduction, in which MTBDC-TPT-Fe had the highest catalytic activity (MTBDC = 2,5-bis(methylthio)terephthalic acid, TPT = 2,4,6-tri(4-pyridyl)− 1,3,5-triazine). The boosted photocatalytic reduction may be mainly ascribed to the enhanced electron push-pull effect between iron-oxygen clusters and organic ligands. The introduction of -SCH 3 groups can enhance the light absorption and donate electrons to iron center under visible-light irradiation, meanwhile the separation and transfer of photogenerated charge carriers can be enhanced resulting from the electron-pulling effect when introducing TPT. Moreover, enhanced specific surface areas and positive skeleton charge due to the introduction of TPT may improve active sites exposure and Cr(VI) adsorption, thereby enhancing photocatalytic Cr(VI) reduction activity without the presence of any assisted scavengers. In addition, the photocatalytic mechanism (i.e. active species) were also studied and presented. This work confirmed an effective structure-performance regulation strategy on Fe-MOFs for photocatalytic Cr(VI) reduction. [Display omitted] • Four novel Fe-MOFs are constructed by ligand modulation for superb photocatalytic Cr(VI) reduction. • The introduction of -SCH 3 group can significantly improve the light absorption ability of Fe-MOF. • TPT ligand can improve the separation and migration of charge carriers through electron-pulling effect. • Larger pores and more positive skeleton formed by TPT introduction are favorable for the adsorption of Cr(VI) substrate. • The e-, ·OH radicals, and O 2 ·- radicals are main active species in the Cr(VI) reduction process. [ABSTRACT FROM AUTHOR]