A new end-on (μ1,1) azido bridged [Zn2(L)2(Na)N3]n 1D chain derived from a trinuclear zinc complex: syntheses,crystal structures,photoluminescence properties and DFT study

A bicompartmental N₂O₄ donor symmetric Schiff base ligand has been deployed to synthesize a trinuclear zinc complex [Zn₃(L)₂Cl₂], which upon treatment with sodium azide produces a new μ_1,1-azido-bridged 1-D polymer [Zn₂(L)₂(Na)N₃]_n. Both complexes have been characterized using IR, NMR, UV–vis, and X-ray diffraction techniques. In order to have better understanding of electronic transitions of the complexes, a time-dependent DFT study has been performed. Lifetime measurements have also been performed to learn about the stability of excited states of both complexes. The average fluorescence decay lifetime has been found to be 1.42 and 0.59 ns for 1 and 2, respectively. In Hirshfeld surface mapping, X?H/H?X (X = O, Cl) contacts are found to be only 2.7% of the total surface, which indicates that no significant X?H/H?X contacts are present in either of the complexes. Unconventional interactions such as C–H?π and π?π stacking interactions are found in supramolecular architectures of both complexes.     

Anion-dependent structural diversity of cadmium(II) complexes: synthesis,crystal structures,luminescence properties,and unusual C-H/σ supramolecular interactions involving σ-aromatic M2X2 cores

Four complexes based on N,N′-bis(2-pyridylmethylene)-1,3-propanediamine (L) and different Cd(II) salts have been synthesized and characterized by single-crystal X-ray diffraction analysis. The complexes are [Cd₂(L)₂(μ-Cl)₂](ClO₄)₂ (1), [Cd₂(L)₂(μ-Br)₂](ClO₄)₂ (2), [Cd(L)I](ClO₄) (3), and [Cd(L)(NCS)₂] (4). L exhibits the same coordination mode in 1–4. The radius of each anion plays a role in affecting the structures and luminescent intensities of the final products. CdCl₂, CdBr₂, and CdI₂ react with L to produce chloride or bromido-bridged binuclear complexes and mononuclear iodido complex, respectively, whereas an unusual mononuclear trigonal prismatic (TP) 4 is obtained when thiocyanate was used as a coligand. Photoluminescence properties of all the complexes show that the trend of fluorescence intensity is 1 > 4 > 2 > 3. All four complexes exhibit different supramolecular interactions such as C–H/σ, π–π, and C–H/π and hydrogen bonding interactions. The experimental findings are complemented by density functional theory (DFT) calculations.     

Direct Structural Identification of Gas Induced Gate‐Opening Coupled with Commensurate Adsorption in a Microporous Metal–Organic Framework

Gate‐opening is a unique and interesting phenomenon commonly observed in flexible porous frameworks, where the pore characteristics and/or crystal structures change in response to external stimuli such as adding or removing guest molecules. For gate‐opening that is induced by gas adsorption, the pore‐opening pressure often varies for different adsorbate molecules and, thus, can be applied to selectively separate a gas mixture. The detailed understanding of this phenomenon is of fundamental importance to the design of industrially applicable gas‐selective sorbents, which remains under investigated due to the lack of direct structural evidence for such systems. We report a mechanistic study of gas‐induced gate‐opening process of a microporous metal–organic framework, [Mn(ina)₂] (ina=isonicotinate) associated with commensurate adsorption, by a combination of several analytical techniques including single crystal X‐ray diffraction, in situ powder X‐ray diffraction coupled with differential scanning calorimetry (XRD‐DSC), and gas adsorption–desorption methods. Our study reveals that the pronounced and reversible gate opening/closing phenomena observed in [Mn(ina)₂] are coupled with a structural transition that involves rotation of the organic linker molecules as a result of interaction of the framework with adsorbed gas molecules including carbon dioxide and propane. The onset pressure to open the gate correlates with the extent of such interaction.     

Synthesis and thermodynamic properties of the perovskite BaRuO3(s) by calorimetry and fluoride ion galvanic cell

Journal of Solid State Electrochemistry - The perovskite BaRuO3(s) shows quasi one-dimensional conduction. The ternary oxide is isoelectronic with the perovskites CaRuO3(s) and SrRuO3(s). The...     

One pot synthesis and gelation studies of amphiphilic triblock polyurethanes

This article shows a generalized synthetic strategy to make amphiphilic ABA type triblock polyurethane (PU) in a SINGLE reaction pot. This is achieved by condensation polymerization between a hydrophobic diol and a di‐isocyanate in the presence of a polyethylene glycol monomethyl ether (M_w = 2000 or 5000 g mol^?1) as mono‐functional impurity. Using different ratios of the three reactants with a fixed parameter such that the total concentration of –OH = isocyanate, a series of PUs are produced with both the ends capped with PEG. These polymers show facile gelation ability in solvents like dimethyl formamide, dimethyl sulfoxide, and dimethyl acetamide by H‐bonding interaction among the urethane groups. A comprehensive structure–property relationship study reveals importance of the right balance between the weight fractions of the soft and hard segments in self‐assembly and efficient gelation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2502–2508     

Antivitamin B12 Inhibition of the Human B12-Processing Enzyme CblC: Crystal Structure of an Inactive Ternary Complex with Glutathione as the Cosubstrate

B₁₂ antivitamins are important and robust tools for investigating the biological roles of vitamin B₁₂. Here, the potential antivitamin B₁₂ 2,4-difluorophenylethynylcobalamin (F2PhEtyCbl) was prepared, and its 3D structure was studied in solution and in the crystal. Chemically inert F2PhEtyCbl resisted thermolysis of its Co−C bond at 100 °C, was stable in bright daylight, and also remained intact upon prolonged storage in aqueous solution at room temperature. It binds to the human B₁₂-processing enzyme CblC with high affinity (K_D=130 nm ) in the presence of the cosubstrate glutathione (GSH). F2PhEtyCbl withstood tailoring by CblC, and it also stabilized the ternary complex with GSH. The crystal structure of this inactivated assembly provides first insight into the binding interactions between an antivitamin B₁₂ and CblC, as well as into the organization of GSH and a base-off cobalamin in the active site of this enzyme.