Synthesis and structure of the adduct dichlorodiaquobis(ethylpropionate)magnesium(II)

The crystal and molecular structure of MgCl₂(H₂O)₂(ethylpropionate)₂ has been determined by single crystal X-ray diffraction analysis. The complex crystallizes in the triclinic system, space group (No. 2);a=5.912 (2),b=5.931 (3),c=12.792 (4) Å, =77.15°(3), =86.21°(3), =88.31°(3);Z=1. The metal lies at the center of a slightly distorted octahedron formed by two chlorine atoms and four oxygens, two from water molecules and two from the carbonyl groups of the ethylpropionate ligands in atrans configuration.     

Water molecules inside protein structure affect binding of monosaccharides with HIV‐1 antibody 2G12

Water molecules inside biomolecules constitute integral parts of their structure and participate in the functions of the proteins. Some of the X‐ray crystallographic data are insufficient for analyzing a series of ligand–protein complexes in the same condition. We theoretically investigated antibody binding abilities of saccharide ligands and the effects of the inner water molecules of ligand–antibody complexes. Classical molecular dynamics and quantum chemical simulations using a model with possible water molecules inside the protein were performed with saccharide ligands and Human Immunodeficiency Virus 1 neutralizing antibody 2G12 complexes to estimate how inner water molecules of the protein affect the dynamics of the complexes as well as the ligand–antibody interaction. Our results indicate the fact that d ‐fructose's strong affinity to the antibody was partly due to the good retentiveness of solvent water molecules of the ligand and its stability of the ligand's conformation and relative position in the active site. © 2016 Wiley Periodicals, Inc.     

Supported proline and proline-derivatives as recyclable organocatalysts

In the last eight years, L-proline and L-proline derivatives, such as substituted prolinamides or pyrrolidines, have been successfully used as organocatalysts in several reactions. In this critical review we summarize the immobilization procedures of such organocatalysts highlighting their application, recoverability and reusability (86 references).     

Mononuclear rearrangement of heterocycles in ionic liquids catalyzed by copper(II) salts

The reactivity of E- and Z-phenylhydrazones of 3-benzoyl-5-phenyl-1,2,4-oxadiazole in the presence of CuCl₂ and Cu(ClO₄)₂·6H₂O has been studied in four imidazolium ionic liquids [bmim][X] (X=BF₄⁻, PF₆⁻, SbF₆⁻ and CF₃SO₃⁻). The reaction may follow different mechanistic patterns, depending on the nature of the ionic liquid anion, accounting for both qualitative and kinetic data. In the presence of CuCl₂, two processes take place at the same time, i.e., the E?Z isomerization and the rearrangement of Z-isomer into the relevant 4-benzoylamino-2,5-diphenyl-1,2,3-triazole. In contrast, in the presence of Cu(ClO₄)₂·6H₂O, the rearrangement occurs only in solution of [bmim][BF₄] and [bmim][CF₃SO₃]. Collected data show that the effect of the ionic liquid on the isomerization and the rearrangement is different. In particular, a higher cross-linking degree seems to favour the triazole, but disfavour the E?Z isomerization.     

Thermodynamic treatment of ligand-receptor interactions

This work reports the development of a physico-chemical model for ligand-receptor interactions. It considers receptors having groups of different binding sites in equilibrium and far from equilibrium where each of these may have multiple occupancies. The obtained results under appropriate simplifications give the well known Scatchard, Hill and Adair relations and provide a very interesting tool for studying receptor-ligand phenomena and for determining the related parameters and interaction energies.     

Hidden in plain sight: unlocking the full potential of cyclic voltammetry with the thin-film rotating (ring) disk electrode studies for the investigation of oxygen reduction reaction electrocatalysts

Cyclic voltammetry conducted with a thin-film rotating disk electrode, or ring-disk electrode (CV-TF-R(R)DE) is a very popular ‘ex situ’ tool for the rapid screening of electrocatalysts for their activity in oxygen reduction reaction. Despite its popularity and broad use, in most instances only a small part of the information that could be accessed by CV-TF-R(R)DE is actually used by scientists in their research. This work outlines both innovative and more traditional (but half-forgotten) ways of using CV-TF-R(R)DE to its optimal or full potential in the ongoing quest to study the most relevant features of oxygen reduction reaction electrocatalysts and quickly identify the most promising candidates for their applications in fuel cells or other electrochemical devices.     

Synthesis,characterization and ionic conductivity of poly[(oligoethylene oxide) ethoxysilane] and poly[(oligoethylene oxide) ethoxysilane]/(EuCl3)0.67

Poly[(oligoethylene oxide) ethoxysilane)] ( I ) and poly[(oligoethylene oxide) ethoxysilane)]/(EuCl₃)_0.67 ( II ) were synthesized by reacting tetraethoxysilane with oligo(ethylene glycol) of molecular weight 400 and oligo(ethylene glycol)400/(EuCl₃)_0.317, respectively. The products so obtained are very transparent and rubbery. By Fourier transform infrared and Raman spectroscopy studies and by using analytical results it was concluded that these products are crosslinked macromolecular materials where the Si atom is bonded to one OEt group and to three poly(ethylene oxide) 400 chains. Scanning electronic microscopy studies showed that the presence of EuCl₃ in polymer host significantly affects the morphology of the material. Laser luminescence investigations on (II) showed that Eu³⁺ ion in the polymer host is accommodated in two different types of sites having a distorted C_2v symmetry. Moreover, the ionic conductivity of these systems was investigated and the data were satisfactorily fitted by the empirical Vogel Tamman Fulcher equation. At 70°C the conductivities of ( I ) and ( II ) were 9 × 10⁻⁶ and 14.3 × 10⁻⁶ Ω⁻¹ cm⁻¹ respectively.     

Cross‐linking of poly(methyl methacrylate) by oxozirconate and oxotitanate clusters

Radical polymerization of methyl methacrylate with 0.5‐2 mol% of the (meth)acrylate‐substituted oxozirconium and oxotitanium clusters Zr₆(OH)₄O₄(OMc)₁₂ (OMc = methacrylate), Zr₄O₂(OMc)₁₂, Ti₆O₄(OEt)₈(OMc)₈ and Ti₄O₂(OPrⁱ)₆(OAcr)₆ (OAcr = acrylate) results in an efficient cross‐linking of the organic polymers. The obtained inorganic‐organic hybrid polymers exhibit a higher thermal stability due to inhibited depolymerization reactions. Contrary to undoped poly(methyl methacrylate), the cluster cross‐linked polymers are insoluble but swell in organic solvents. The solvent uptake upon swelling decreases with an increasing amount of polymerized cluster. The impedance spectra of PMMA doped with various proportions of Zr₄O₂(OMc)₁₂ show that the capacitance of the polymers decreases with an increasing proportion of the cluster. The polymer doped with 2 mol% of Zr₄O₂(OMc)₁₂ shows an increase in conductivity to 0.9·10⁻⁷ S·cm⁻¹ at 74°C.