Metal–organic frameworks with 5,5′-(1,4-xylylenediamino) diisophthalic acid and various nitrogen-containing ligands for selectively sensing Fe(iii)/Cr(vi) and nitroaromatic compounds

Abstract

Four novel Zn(II) metal–organic frameworks (MOFs) including {[Zn(L)_0.5(bimb)]·2H₂O·0.5(CH₃)₂NH}_n (1), {[Zn(L)_0.5(bimmb)]·2H₂O}_n (2), {[Zn(L)_0.5(btdpe)]·H₂O}_n (3), and [Zn(L)_0.5(bidpe)]_n (4) (H₄L = 5,5′-(1,4-xylylenediamino) diisophthalic acid, bimb = 1,4-bis(imidazol-1-yl)-butane, bimmb = 1,4-bis(imidazol-1-ylmethyl)benzene, btdpe = 4,4′-bis(4H-1,2,4-triazol-4-yl)diphenyl ether, and bidpe = 4,4′-bis(imidazolyl)diphenyl ether) were solvothermally prepared and further characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction, thermogravimetric (TG) analysis and powder X-ray diffraction (PXRD). Single-crystal X-ray diffraction analysis showed that complex 1 features a 3-fold interpenetrated bbf topological framework with the Schläfli symbol of (6⁴·8²)(6⁶)₂. Complex 2 displayed an unprecedented 2-nodal (4,4)-connected 3D framework with the Schläfli symbol of (8⁶), while complexes 3 and 4 showed 3-nodal (2,4,4)-connected (4·8·10⁴)₂(4)₂(8⁴·10·12)-unprecedented frameworks. Luminescence studies revealed that complexes 1–4 can be used as high selectivity luminescence sensors for sensing Fe(III) cations, Cr(VI) anions (Cr₂O₇²⁻ and CrO₄²⁻) and nitroaromatic compounds. Furthermore, a possible sensing mechanism was investigated in this paper.