Biphenyl-4,4′-dicarb­oxy­lic acid N,N-dimethyl­formamide monosolvate

Biphenyl-4,4′-dicarb­oxy­lic acid was recrystallized from N,N-dimethyl­formamide (DMF) yielding the title compound, C14H10O4·2C3H7NO. The acid mol­ecules are located on crystallographic centres of inversion and are hydrogen bonded to DMF mol­ecules. These hydrogen-bonded units form infinite chains although there is no inter­action between the methyl groups of neighboring DMF mol­ecules

Poly[tris­(μ-2-amino­benzene-1,4-dicarboxyl­ato)tetra­kis­(N,N-dimethyl­formamide)­diyttrium(III)]

The asymmetric unit of the title coordination polymer, [Y2(C8H5NO4)3(C3H7NO)4]n, contains one Y3+ ion, three half-mol­ecules of the 2-amino­benzene-1,4-dicarboxyl­ate (abz) dianion and two O-bonded N,N-dimethyl­formamide (DMF) mol­ecules. Each abz half-mol­ecule is completed by crystallographic inversion symmetry and its –NH2 group is disordered in each case [relative occupancies within the asymmetric unit = 0.462 (18):0.538 (18), 0.93 (2):0.07 (2) and 0.828 (16):0.172 (16)]. The combination of disorder and crystal symmetry means that each of the four C—H atoms of the benzene ring of each of the dianions bears a statistical fraction of an –NH2 group. The coordination geometry of the yttrium ion is a fairly regular YO8 square anti­prism arising from its coordination by two DMF mol­ecules, four monodentate abz dianions and one O,O-bidentate abz dianion. The polymeric building unit is a dimeric paddle-wheel with two metal ions linked by four bridging abz dianions. Further bridging linkages connect the dimers into a three-dimensional framework containing voids in which highly disordered DMF mol­ecules are presumed to reside

Co-catalyst free ethene dimerization over Zr-based metal-organic framework (UiO-67) functionalized with Ni and bipyridine

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XAS on Rh and Ir metal sites in post synthetically functionalized UiO-67 Zirconium MOFs

We synthesized UiO-67 metal-organic-frameworks (MOFs) functionalized with different transition metals (Rh, Ir). Using EXAFS we verified that the synthesis has been successful. Furthermore, we observed the change of local environment while varying of metal site. XAS spectroscopy is the most informative technique to characterize these kind of materials and to study the local environment around the metal site

Di-μ-chlorido-bis[2,2'-bipyridine-5,5'-dicarboxylic acid-κ2N,N')chloridocopper(II)]dimethylformamide tetrasolvate

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Twinning in Zr-Based Metal-Organic Framework Crystals

Ab initio structure determination of new metal-organic framework (MOF) compounds is generally done by single crystal X-ray diffraction, but this technique can yield incorrect crystal structures if crystal twinning is overlooked. Herein, the crystal structures of three Zirconium-based MOFs, that are especially prone to twinning, have been determined from twinned crystals. These twin laws (and others) could potentially occur in many MOFs or related network structures, and the methods and tools described herein to detect and treat twinning could be useful to resolve the structures of affected crystals. Our results highlight the prevalence (and sometimes inevitability) of twinning in certain Zr-MOFs. Of special importance are the works of Howard Flack which, in addition to fundamental advances in crystallography, provide accessible tools for inexperienced crystallographers to take twinning into account in structure elucidation