Three new ZnII coordination polymers constructed from a semi-rigid tricarboxylic acid: structural changes caused by flexibility and luminescence sensing for hexavalent chromate anions

Two new NiII and ZnII metal-organic frameworks of glutarate and 1,4-bis[(2-methyl-1H-imidazol-1-yl)methyl]benzene ligands: syntheses, structures and luminescence sensing properties

Two new metal-organic frameworks (MOFs), namely, three-dimensional poly[diaquabis{μ₂-1,4-bis[(2-methyl-1H-imidazol-1-yl)methyl]benzene}bis(μ₂-glutarato)dinickel(II)] monohydrate], {[Ni₂(C₅H₆O₄)₂(C₁₆H₁₈N₄)₂(H₂O)₂]·H₂O}_n or {[Ni₂(Glu)₂(1,4-mbix)₂(H₂O)₂]·H₂O}_n, (I), and two-dimensional poly[[{μ₂-1,4-bis[(2-methyl-1H-imidazol-1-yl)methyl]benzene}(μ₂-glutarato)zinc(II)] tetrahydrate], {[Zn(C₅H₆O₄)(C₁₆H₁₈N₄)]·4H₂O}_n or {[Zn(Glu)(1,4-mbix)]·4H₂O}_n (II), have been synthesized hydrothermally using glutarate (Glu^2-) mixed with 1,4-bis[(2-methyl-1H-imidazol-1-yl)methyl]benzene (1,4-mbix), and characterized by single-crystal X-ray diffraction, IR and UV-Vis spectroscopy, powder X-ray diffraction, and thermogravimetric and photoluminescence analyses. Ni^II MOF (I) shows a 4-connected 3D framework with point symbol 6⁶, but is not a typical dia network. Zn^II MOF (II) displays a two-dimensional 4⁴-sql network with one-dimensional water chains penetrating the grids along the c direction. The solid-state photoluminescence analysis of (II) was performed at room temperature and the MOF exhibits highly selective sensing toward Fe³⁺ and Cr₂O₇^2- ions in aqueous solution.