Two new isomeric zinc(II) metal-organic frameworks based on 1,5-bis(2-methyl-1H-imidazol-1-yl)pentane and 5-methylisophthalate ligands.

Many factors, such as temperature, solvent, the central metal atom and the type of coligands, may affect the nature of metal-organic frameworks (MOFs) and the framework formation in the self-assembly process, which results in the complexity of these compounds and the uncertainty of their structures. Two new isomeric Zn metal-organic frameworks (MOFs) based on mixed ligands, namely, poly[[μ-1,5-bis(2-methyl-1H-imidazol-1-yl)pentane-κN:N](μ-5-methylisophthalato-κO:O)zinc(II)], [Zn(CHO)(CHN)], (I), and poly[[μ-1,5-bis(2-methyl-1H-imidazol-1-yl)pentane-κN:N](μ-5-methylisophthalato-κO:O:O)(μ-5-methylisophthalato-κO:O:O,O)dizinc(II)], [Zn(CHO)(CHN)], (II), have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis and thermogravimetric analysis. Complex (I) displays a two-dimensional layer net, while complex (II) exhibits a twofold interpenetrating three-dimensional framework.

Poly[[tetra-aqua-tetra-kis-[μ(3)-5-(pyridine-4-carboxamido)-isophthalato]cobalt(II)dierbium(III)] tetra-hydrate].

In the centrosymmetric polymeric title compound, {[CoEr(2)(C(14)H(8)N(2)O(5))(4)(H(2)O)(4)]·4H(2)O}(n), the Er(III) cation has a coordination number of eight and is surrounded by seven carboxyl-ate O atoms from four 5-(pyridine-4-carboxamido)-isophthalate (L) ligands and one water mol-ecule, forming a distorted square-anti-prismatic arrangement. The Co(II) cation is located on an inversion center and is coordinated by two pyridine N atoms, two carboxyl-ate O atoms and two water mol-ecules in a distorted octa-hedral geometry. The asymmetric unit contains two anionic L ligands.