New Metal–Organic Framework Solids Built from Barium and Isoelectronic Chelidamic and Chelidonic Acids

Abstract  

Two new Ba(II) metal–organic framework solids bearing the chelidamate [Ba₂(C₇H₃NO₅)₂(μ-H₂O)(H₂O)₆]·2H₂O (1) and chelidonate [Ba(C₇H₂O₆)(H₂O)] (2) ligands were synthesized and characterized by IR, elemental, thermal, photoluminescent and X-ray diffraction analyses. In complex 1 the chelidamate dianion exists in two tautomeric forms, in which the enol form exhibits unprecedented (К¹, К¹) (К¹) (К², К², μ₂, μ₂)-μ₇ heptadentate coordination while the keto form with (К¹, К¹)(К²)-μ₄ tetradentate mode. It is a 2D polymer in which the first and second dimensions are satisfied by carboxylate oxygens while the third is by the combination of hydrogen bonds and π–π stacking of aromatic rings. There are two independent barium ions (Ba1, Ba2) in complex 1 that are nine coordinated, but their coordination environment is different. Complex 2 is a 3D polymer and the organic linker, 4-oxo-pyran-2,6-dicarboxylate (chelidonate) anion exhibits denticity as seven with barium having the similar nine coordination.     

Columnar Mesophase Formation of Cyclohexa‐m‐phenylene‐Based Macrocycles

Two novel discotic macrocycles, substituted cyclohexa‐m‐phenylene (CHP) and cyclo‐3,6‐trisphenanthrylene (CTP), and the linear oligomer 3,3′:6′,3′′‐terphenanthrene (TP) as a model substance have been synthesized by repetitive cross‐coupling reactions. To correlate the molecular design with the supramolecular architecture and the established macroscopic order, 2D wide‐angle X‐ray scattering experiments were performed on mechanically extruded filaments. At room temperature in their crystalline phases, all three compounds revealed columnar assemblies in which the macrocycles self‐organized by π‐stacking interactions. The degree of macroscopic order was found to depend upon the planarity and stiffness of the aromatic core. The flexible CHP ring showed a poor macroscopic order of the columnar structures and a low isotropization temperature, whereas the more‐planar, less‐flexible CTP self‐assembled into well‐defined superstructures. The larger π‐stacking area and the more‐pronounced intermolecular interactions for CTP led to the formation of a mesophase over a very large temperature range. The surprising columnar organization of the “open” TP system was explained by back‐folding of the molecule into a ringlike structure.     

Molecular Triangles: Synthesis,Self‐Assembly,and Blue Emission of Cyclo‐7,10‐tris‐triphenylenyl Macrocycles

A set of cyclo‐7,10‐tris‐triphenylenyl macrocycles have been prepared by a Yamamoto cyclotrimerization protocol. In these novel macrocycles, three triphenylene units are covalently linked to each other, resulting in the formation of triangular‐shaped molecules. The fully planar derivative revealed pronounced self‐assembly behavior. NMR spectroscopy was used to determine the association constant in solution. 2D wide‐angle X‐ray scattering was applied to the study of the liquid crystallinity of this new discotic mesogen in the bulk state. Furthermore, nonplanar, laterally substituted derivatives were successfully tested as blue emitters in organic light‐emitting diodes owing to their unique optoelectronic properties and their high stability. In this case, substitution with sterically demanding phenyl groups was efficiently used to suppress intermolecular packing, thus preventing undesired quenching effects.     

The role of carboxylate ligands in two novel cyanido-bridged 2D coordination networks Cu(II)-W(V) and Mn(II)-Nb(IV)

We report on the synthesis, molecular structure and magnetic properties of two novel coordination polymers: [{Cu(II)(4)(pic)(2)(H(2)O)(2)(MeOH)}{W(V)(CN)(8)}(2)]·MeOH·4H(2)O (1) and [{Mn(II)(3)(HCOO)(2)(H(2)O)(4)}{Mn(II)(H(2)O)(3)(HCONH(2))}(2){Nb(IV)(CN)(8)}(2)]·4HCONH(2)·2H(2)O (2). The single-crystal X-ray diffraction analysis of 1 shows that its molecular structure can be interpreted as a cyanido bridged (3,4,7)-connected 2D bilayer built of two different subnets sharing the tungsten centers. The magnetic measurements suggest that the system reveals long-range ferromagnetic ordering between Cu(II) and W(V) centers below 13.4 K. The molecular structure of (2) reveals a 2D topology of layers built of cyanido and formato bridging ligands. The system reveals ferrimagnetic behavior with a critical temperature at 17.8 K.     

Inhibition of inflammatory mediators by neobavaisoflavone in activated RAW264.7 macrophages

Flavonoids and coumarins are the major bioactive constituents identified in Psoralea corylifolia. The active fraction isolated from fruits, seeds and roots possesses antibacterial, antioxidative and immunomodulatory properties. Neobavaisoflavone is one of the flavonoids found in Psoralea corylifolia. In the present study we investigated in vitro the anti-inflammatory activity of neobavaisoflavone. Macrophages play an important role in inflammation through the release of inflammatory mediators involved in the immune response. Inappropriate and prolonged macrophage activation is largely responsible for the pathology of acute and chronic inflammatory conditions. Neobavaisoflavone significantly inhibited the production of reactive oxygen species (ROS), reactive nitrogen species (RNS) and cytokines: IL-1β, IL-6, IL-12p40, IL-12p70, TNF-α in LPS+IFN-γ- or PMA- stimulated RAW264.7 macrophages.     

Hydrophobic modification of polycarbonate for reproducible and stable formation of biocompatible microparticles

We propose a simple and effective scheme for the modification of the walls of microfluidic channels fabricated in polycarbonate (PC) after the device has been bonded. The method prevents both static and dynamic wetting of PC by aqueous solutions including viscous, non-Newtonian solutions of polymers as e.g. alginate. The procedure uses dodecylamine, which readily reacts with the carbonate groups of PC to produce a hydrophobic surface. We characterize the dependence of the contact angles and homogeneity of the modified surfaces on the time, temperature, and concentration-all important parameters-of the reaction and provide optimal conditions for the process.     

Large changes of static electric properties induced by hydrogen bonding: an ab initio study of linear HCN oligomers

We report the partitioning of the interaction-induced static electronic dipole (hyper)polarizabilities for linear hydrogen cyanide complexes into contributions arising from various interaction energy terms. We analyzed the nonadditivities of the studied properties and used these data to predict the electric properties of an infinite chain. The interaction-induced static electric dipole properties and their nonadditivities were analyzed using an approach based on numerical differentiation of the interaction energy components estimated in an external electric field. These were obtained using the hybrid variational-perturbational interaction energy decomposition scheme, augmented with coupled-cluster calculations, with singles, doubles, and noniterative triples. Our results indicate that the interaction-induced dipole moments and polarizabilities are primarily electrostatic in nature; however, the composition of the interaction hyperpolarizabilities is much more complex. The overlap effects substantially quench the contributions due to electrostatic interactions, and therefore, the major components are due to the induction and exchange-induction terms, as well as the intramolecular electron-correlation corrections. A particularly intriguing observation is that the interaction first hyperpolarizability in the studied systems not only is much larger than the corresponding sum of monomer properties, but also has the opposite sign. We show that this effect can be viewed as a direct consequence of hydrogen-bonding interactions that lead to a decrease of the hyperpolarizability of the proton acceptor and an increase of the hyperpolarizability of the proton donor. In the case of the first hyperpolarizability, we also observed the largest nonadditivity of interaction properties (nearly 17%) which further enhances the effects of pairwise interactions.