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

Four novel Zn(II) metal–organic frameworks (MOFs) including {[Zn(L)0.5(bimb)]&#183;2H2O&#183;0.5(CH3)2NH}n (1), {[Zn(L)0.5(bimmb)]&#183;2H2O}n (2), {[Zn(L)0.5(btdpe)]&#183;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 Schlafli symbol of (64&#183;82)(66)2. Complex 2 displayed an unprecedented 2-nodal (4,4)-connected 3D framework with the Schlafli symbol of (86), while complexes 3 and 4 showed 3-nodal (2,4,4)-connected (4&#183;8&#183;104)2(4)2(84&#183;10&#183;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.