F.A. Almeida Paz

Highly emissive Zn–Ln metal–organic frameworks with an unusual 3D inorganic subnetwork

Mixed zinc-lanthanide (Zn-Ln) metal-organic frameworks (MOFs) based on the 3,5-pyrazoledicarboxylate ligand exhibit an unusual three-dimensional (3D) inorganic subnetwork and display highly efficient photoluminescence.

Poly[hexa­aqua­bis(μ3-naphthalene-2,6-dicarboxyl­ato)(μ2-naphthalene-2,6-dicarboxyl­ato)diholmium(III)]

The crystal structure of the title compound, [Ho2(C12H6O4)3(H2O)6]n, contains binuclear centrosymmetric {Ho2O2(CO2)4(H2O)6} cores interconnected via the naphthalene-2,6-dicarboxylate (NDC2−) bridging ligands into a two-dimensional neutral plane net, ∞2[Ho2(NDC)3(H2O)6], exhibiting a typical (4,4)-topology. Interactions between adjacent layers are assured by a series of C—H⋯π contacts and a number of strong and highly directional O—H⋯O hydrogen bonds involving the coordinated water molecules and neighbouring coordinated carboxylate groups. One NDC2− bridging ligand has its centroid located at a crystallographic centre of inversion.

Site-selective Eu(III) spectroscopy of highly efficient luminescent mixed-metal Pb(II)/Eu(III) coordination polymers

Novel mixed-metal coordination polymers (CPs) based on Pb1−xEux–BDC (x = 0.05, 0.10, 0.25, 0.50 and BDC = 1,4-benzenedicarboxylic acid) are reported. The materials display different coordination structures as the Pb : Eu metal ratio is modified. Whereas for x 0.25 the samples are isotypical with [Eu2(BDC)3(H2O)4], as shown by powder (including Rietveld analysis) and single-crystal X-ray diffraction. The unique Pb0.75Eu0.25–BDC compound displays a mixture of both crystalline phases with the highest emission quantum yield value reported for luminescent CPs based on Pb(II), 69 ± 7%. Site-selective excitation using a common Xe lamp permits the detailed study of the two Eu3+ local sites, illustrating how powerful the Eu3+ luminescence is as a local probe spectroscopic tool.

Redetermination at 180 K of a layered lanthanide–organic framework

The asymmetric unit of the title compound, poly[(μ4-{[bis(hydrogen phosphonatomethyl)azaniumyl]methyl}phosphonato)lanthanum(III)], [La(C3H9NO9P3)]n, comprises an La3+ center and a H3nmp3− anion (where H3nmp3− is a residue of partially deprotonated nitrilotris(methylenephosphonic acid), namely {[bis(hydrogen phosphonatomethyl)azaniumyl]methyl}phosphonate). This study concerns a structural redetermination using single-crystal X-ray diffraction data, collected at the low temperature of 180 K, of a recently investigated material whose structural details have been proposed from powder X-ray diffraction studies [Silva et al. (2011 ▶). J. Am. Chem. Soc. 133, 15120–15138]. The main difference between the two models rests on the position of the H atoms. While two H atoms were modeled as attached to the same phosphonate group in the powder determination, in the current model, the same H atoms are instead distributed among two of these groups. The sample studied was an inversion twin.

μ-Oxido-bis­[chlorido(4,4′-di-tert-butyl-2,2′-bipyridine-κ2N,N′)dioxido­molybdenum(VI)] 0.2-hydrate

The title hydrate, [Mo2Cl2O5(C18H24N2)2]·0.2H2O, has been isolated as the oxidation product of [Mo(η3-C3H5)Cl(CO)2(di-t-Bu-bipy)] (where di-t-Bu-bipy is 4,4′-di-tert-butyl-2,2′-bipyridine). A μ-oxide ligand bridges two similar MoCl(di-t-Bu-bipy)O2 units, having the terminal oxide ligands mutually cis, and the chloride and μ-oxide trans to each other. In the binuclear complex, the coordination geometries of the metal atoms can be described as highly distorted octahedra. Individual complexes co-crystallize with a partially occupied water molecule of crystallization (occupancy factor = 0.20; H atoms not located), with the crystal packing being mediated by the need to effectively fill the available space. A number of weak C—H⋯O and C—H⋯Cl interactions are present.

catena-Poly[[triaqua­chlorido-μ3-malonato-cerium(III)] hemihydrate]

The asymmetric unit of the title compound, {[Ce(C3H2O4)Cl(H2O)3]·0.5H2O}n, contains a Ce3+ atom coordinated by a chloride anion, three water molecules and a malonate ligand, and one water molecule of crystallization with a factor of occupancy of 50%. The malonate ligand is bonded to three different symmetry-related metal atoms yielding a one-dimensional coordination polymer running parallel to the a axis. A supramolecular network composed of strong and highly directional O—H⋯O and O—H⋯Cl hydrogen bonds ensures a close and effective packing of adjacent polymeric chains.

4,4′-Di-tert-butyl-2,2′-bipyridine

In the title compound, C18H24N2, the molecular unit adopts a trans conformation around the central C—C bond [N—C—C—N torsion angle of 179.2 (3)°], with the two aromatic rings almost coplanar [dihedral angle of only 0.70 (4)°]. The crystal packing is driven by co-operative contacts involving weak C—H⋯N and C—H⋯π interactions, and also the need to fill effectively the available space.

(E)-3-[(Di­methyl­amino)­methyl­idene]-4-phenyl-1-(prop-2-yn­yl)-1H-1,5-benzodiazepin-2(3H)-one

The title compound, C21H19N3O, exhibits an E configuration with respect to the C=C bond between the benzodiazepine and trimethylamine groups. The seven-membered diazepine ring displays a boat conformation. In the crystal, molecules are linked by a C—H⋯O hydrogen bond, forming a chain along [110].

Diaqua­bis(ethyl­enediamine-κ2N,N′)copper(II) bis­(4-phenyl­benzoate) 2.66-hydrate

In the title complex, [Cu(C2H8N2)2(H2O)2](C13H9O2)2·2.66H2O, the CuII centre (located at an inversion centre) is coordinated by two bidentate ethylenediamine (en) ligands and two water O atoms in a typical Jahn–Teller distorted octahedral geometry. The amino groups and the water molecules are disordered over two distinct crystallographic positions with occupancies of 1/3 and 2/3. In the crystal, the cations and anions are disposed in alternating layers. One of the water molecules of crystallization is disordered and the other has a fractional occupation. In the 2/3 occupancy component, water molecules are organized into a chain composed of hexameric units interconnected by carboxylate bridges.

Methyl 2-(4,6-dichloro-1,3,5-triazin-2-yl­amino)acetate

The title compound, C6H6Cl2N4O2, was prepared by the nucleophilic substitution of 2,4,6-trichloro-1,3,5-triazine by glycine methyl ester hydrochloride, and was isolated from the reaction by using flash chromatography. The crystal structure at 150 K reveals the presence two crystallographically independent molecules in the asymmetric unit which differ in the orientation of the pendant methoxycarbonyl group. Each molecular unit is engaged in strong and highly directional N—H⋯N hydrogen-bonding interactions with a symmetry-related molecule, forming supramolecular dimers which act as the synthons in the crystal packing.