MOF-Derived Cu3P nanoparticles Coated by N-doped carbon for Nitrogen Fixation

Electrochemical nitrogen reduction is a significant alternative route to synthesize ammonia, while constructing efficient catalysts for electrochemical nitrogen fixation still faces tough challenges. In this work, the Cu3P@NC (NC, nitrogen-doped...

Modeling Solid State Stability for Speciation: A Ten-Year Long Study

Speciation studies are based on fundamental models that relate the properties of biomimetic coordination compounds to the stability of the complexes. In addition to the classic approach based on solution studies, solid state properties have been recently proposed as supporting tools to understand the bioavailability of the involved metal. A ten-year long systematic study of several different complexes of imidazole substituted ligands with transition metal ions led our group to the definition of a model based on experimental evidences. This model revealed to be a useful tool to predict the stability of such coordination complexes and is based on the induced behavior under thermal stress. Several different solid state complexes were characterized by Thermally Induced Evolved Gas Analysis by Mass Spectrometry (TI-EGA-MS). This hyphenated technique provides fundamental information to determine the solid state properties and to create a model that relates stability to coordination. In this research, the model resulting from our ten-year long systematic study of complexes of transition metal ions with imidazole substituted ligands is described. In view of a systematic addition of information, new complexes of Cu(II), Zn(II), or Cd(II) with 2-propyl-4,5-imidazoledicarboxylic acid were precipitated, characterized, and studied by means of Thermally Induced Evolved Gas Analysis performed by mass spectrometry (TI-EGA-MS). The hyphenated approach was applied to enrich the information related to thermally induced steps, to confirm the supposed decomposition mechanism, and to determine the thermal stability of the studied complexes. Results, again, allowed supporting the theory that only two main characteristic and common thermally induced decomposition behaviors join the imidazole substituted complexes studied by our group. These two behaviors could be considered as typical trends and the model allowed to predict coordination behavior and to provide speciation information.

Five metal–organic frameworks from 3,4-dimethylphenyl substituted imidazole dicarboxylate: syntheses, structures and properties

Five metal–organic frameworks have been hydrothermally synthesized and structurally characterized.

A new three-dimensional silver(I) coordination framework with a diamondoid topology constructed from 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylic acid

The title compound, poly[[μ4-5-carboxy-4-carboxylato-2-(pyridin-4-yl)-1H-imidazol-1-ido]disilver(I)], [Ag2(C10H5N3O4)]n, was synthesized by reacting silver nitrate with 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylic acid (H3PyIDC) under hydrothermal conditions. The asymmetric unit contains two crystallographically independent Ag(I) cations and one unique HPyIDC(2-) anion. Both Ag(I) cations are three-coordinated in distorted T-shaped coordination geometries. One Ag(I) cation is coordinated by one N and two O atoms from two HPyIDC(2-) anions, while the other is bonded to one O and two N atoms from two HPyIDC(2-) anions. It is interesting to note that the HPyIDC(2-) group acts as a μ4-bridging ligand to link the Ag(I) cations into a three-dimensional framework, which can be simplified as a diamondoid topology. The thermal stability and photoluminescent properties of the title compound have also been studied.

Triaqua[2,2'-(propane-1,3-diyl)bis(5-carboxy-1H-imidazole-4-carboxylato-κ(2)N(3),O(4))]calcium(II) tetrahydrate

In the title compound, [Ca(C(13)H(10)N(4)O(8))(H(2)O)(3)]·4H(2)O, the Ca(II) ion is hepta-coordinated by two N atoms and two O atoms from a tetra-dentate 1,3-bis-(1H-imidazole-4,5-dicarb-oxy-l-ate) propane dianion and three water O atoms, giving a distorted penta-gonal-bipyramidal coordination environment. The Ca-O bond lengths are in the range 2.354 (3)-2.453 (2) Å, while the Ca-N bond lengths are in the range 2.523 (2)-2.548 (2) Å. An intra-molecular O-H⋯O hydrogen bond between the carb-oxy and carboxyl-ate groups stabilizes the mol-ecular configuration. A three-dimensional network of N-H⋯O and O-H⋯O hydrogen bonds help to stabilize the crystal packing.

Aqua-[2,2'-(propane-1,3-di-yl)bis-(5-car-boxy-1H-imidazole-4-carboxyl-ato)-κ(4)N(3),O(4):N(3'),O(4')](pyridine-κN)cobalt(II)-4,4'-bipyridine (1/1)

In the title compound, [Co(C₁₃H₁₀N₄O₈)(C₅H₅N)(H₂O)]·C₁₀H₈N₂, the asymmetric unit comprises half a Co^II complex located on a mirror plane and half a cocrystallized mol­ecule of 4,4′-bipyridine located on an inversion center. The Co^II ion is six coordinate, with distorted octa­hedral geometry, ligated by two N atoms and two O atoms from a 2,2′-(propane-1,3-di­yl)bis­(5-carboxy-1H-imidazole-4-carboxyl­ate) dianion, one N atom from a pyridine mol­ecule and one coordinating water mol­ecule. The Co—O bond lengths range from 2.076 (2) to 2.1441 (15) Å, while the Co—N bond lengths are 2.138 (3) and 2.1515 (17) Å. A two-dimensional network of N—H⋯O and O—H⋯N hydrogen bonds stabilizes the crystal packing. There are π–π inter­actions between the bipyridine and imidazole rings [centroid–centroid distance = 3.7694 (4) Å]. The propane-1,3-diyl group is disordered over two conformations, with refined occupancies of 0.755 (8) and 0.245 (8).