Ion Channel Behavior of a Supported Bilayer Lipid Membrane Composed of 5,5-Ditetradecyl-2-(2-trimethyl-ammonioethyl)-1,3-dioxane Bromide Modified Glassy Carbon Electrode

A synthetic cationic surfactant, 5, 5-ditetradecyl-2-(2-trimethyl-ammonioethyl)-1, 3-dioxane bromide (DTDB), was used toconstruct a supported bilayer lipid membrane (s-BLM) coatedon an underlying glassy carbon electrode (GCE). Electrochem-ical impedance spectroscopy (EIS), small-angle X-ray diffrac-tion (SAXD) and cyclic voltammetry were used to characterizethe s-BLM. Both EIS and SAXD data indicated that the syn-thetic lipid exists as a well-oriented bilayer in the membrane.     

Thermal Behavior of 2‐(Dinitromethylene)‐1,3‐diazacyclopentane

A new compound, 2‐(dinitromethylene)‐1,3‐diazacyclopentane (DNDZ), was prepared by the reaction of 1,1‐diamino‐2,2‐dinitroethylene (FOX‐7) with 1,2‐diaminoethane in N‐methylpyrrolidone (NMP). Thermal decomposition of DNDZ was studied under non‐isothermal conditions by DSC, TG/DTG methods, and the enthalpy, apparent activation energy and pre‐exponential factor of the exothermic decomposition reaction were obtained as 317.13 kJ·mol^?1, 269.7 kJ·mol^?1 and 10^24.51 s^?1, respectively. The critical temperature of thermal explosion was 261.04°C. Specific heat capacity of DNDZ was determined with a micro‐DSC method and a theoretical calculation method, and the molar heat capacity was 205.41 J·mol^?1·K^?1 at 298.15 K. Adiabatic time‐to‐explosion was calculated to be a certain value between 263–289 s. DNDZ has higher thermal stability than FOX‐7.     

Phase Behavior of a Designed Cyclopropyl Analogue of Monoolein: Implications for Low‐Temperature Membrane Protein Crystallization

Lipidic cubic phases (LCPs) are used in areas ranging from membrane biology to biodevices. Because some membrane proteins are notoriously unstable at room temperature, and available LCPs undergo transformation to lamellar phases at low temperatures, development of stable low‐temperature LCPs for biophysical studies of membrane proteins is called for. Monodihydrosterculin (MDS) is a designer lipid based on monoolein (MO) with a configurationally restricted cyclopropyl ring replacing the olefin. Small‐angle X‐ray scattering (SAXS) analyses revealed a phase diagram for MDS lacking the high‐temperature, highly curved reverse hexagonal phase typical for MO, and extending the cubic phase boundary to lower temperature, thereby establishing the relationship between lipid molecular structure and mesophase behavior. The use of MDS as a new material for LCP‐based membrane protein crystallization at low temperature was demonstrated by crystallizing bacteriorhodopsin at 20 °C as well as 4 °C.     

Electrochemical Investigation of Na‐Salt of 2‐Methyl‐3‐(4‐nitrophenyl)acrylate on Glassy Carbon Electrode

The electrochemical behavior of Na‐salt of 2‐methyl‐3‐(4‐nitrophenyl)acrylate (NPA) and its reduction product was studied by cyclic (CV), differential pulse(DPV) and square wave voltammetry (SWV) using a glassy carbon electrode (GCE). The results revealed that NPA is irreversibly reduced leading to the formation of a reduction product (P_NPA). For pH<9.0 the peak potential was linearly dependent on pH. For pH>9.0 the peak potential was pH‐independent and the value of pK_b≈9.0 was determined. The adsorbed P_NPA exhibited reversible redox reaction. The reduction of P_NPA was pH dependent. To ensure that the electrochemical behavior of NPA is due to the reducible moiety, NO₂, closely related compounds to NPA were also studied, and a redox mechanism was proposed for NPA.     

Atomic Force Microscopy and X‐Ray Photoelectron Spectroscopy of Lead(II) Membrane Electrode Based on Dithiodibenzoic Acid as Ionophore

The use of 1‐butyl‐3‐methylimidazolium hexafluorophosphate ionic liquid [C₄mim][PF₆] as additive in a Pb(II) plastic membrane electrode increased significantly the selectivity of the sensor. Atomic force microscopy and depth profiling X‐ray photoelectron spectroscopy were applied to investigate the compositional and morphological changes of the surface and bulk of the membrane during the conditioning process of the electrode.     

Characterization of a 2‐Benzo[c]cinnoline Modified Glassy Carbon Electrode by Raman Spectroscopy,Electrochemical Impedance Spectroscopy,and Ellipsometry

This work describes the characterization of the grafted 2‐benzo[c]cinnoline (2BCC) molecules at a glassy carbon (GC) electrode surface by voltammetry and spectroscopy. Attachment of the molecule to the carbon substrate was achieved by the electrochemical reduction of 2‐benzo[c]cinnoline diazonium salt (2BCC‐DAS). GC electrode modification was carried out in aprotic solution with 2BCC diazonium salt. Dopamine (DA) and ascorbic acid (AA) were used to prove the surface modification to see the blockage of the electron transfer. The presence of 2BCC at the GC electrode surface was characterized by cyclic voltammetry and Raman spectroscopy. Raman spectroscopy was used to monitor molecular bound properties of the adsorbates at the 2BCC‐GC surface and confirm the attachment of 2BCC molecules onto the GC surface. The thickness of the 2BCC film on GC was also investigated by ellipsometric measurement.     

Anodic Stripping Voltammetric Determination of Mercury(II) in Water Using a 4‐Tert‐Butyl‐1‐(Ethoxycarbonylmethoxy)Thiacalix[4]Arene Modified Glassy Carbon Electrode

A glassy carbon electrode coated the film of 4‐tert‐butyl‐1‐(ethoxycarbonylmethoxy)thiacalix[4]arene is designed for the determination of trace amounts of Hg²⁺. Compared with bare glassy carbon electrode, the modified electrode can improve the measuring sensitivity of Hg²⁺. Under the optimum experimental condition, the modified electrode in 0.1 mol L^?1 H₂SO₄ + 0.01 mol L^?1 KCl solution shows a linear voltammetric response in the range of 8.0 × 10^?9 ～ 3.0 × 10^?6 mol L^?1 with detection limit 5.0 × 10^?9 mol L^?1 for Hg²⁺. The high sensitivity, selectivity, and stability of modified electrode also prove its practical application for a simple, rapid and economical determination of Hg²⁺ in water samples.     

Isotopic splitting patterns in the 13C NMR spectra of some partially deuterated 1‐aryl‐2‐(phenyldiazenyl)butane‐1,3‐dione and 4‐hydroxy‐3‐(phenyldiazenyl)‐2H‐chromen‐2‐one: evidence for elucidation of tautomeric forms

Nuclear magnetic resonance spectra of synthesized azo dyes derived from aniline derivatives in reaction with benzoylacetone and 4‐hydroxycoumarin were studied in both CDCl₃ and (CD₃)₂SO (two drops of D₂O were added into solutions of dyes). All dyes showed intramolecular hydrogen bonding. Dyes derived from o‐nitro aniline in the reaction with benzoylacetone, and 4‐hydroxycoumarin showed bifurcated intramolecular hydrogen bonds. The solvent‐substrate proton exchange of dyes derived from benzoylacetone and 4‐hydroxycoumarin was examined in the presence of two drops of D₂O. Among ten dye samples, two dyes derived from benzoylacetone did not show deuteration, three dyes showed partial deuteration and five dyes showed full deuteration under similar conditions. For the partially deuterated dyes the β‐isotope effect in ¹³C splitting was investigated and was used for the determination of the predominant tautomeric form. Copyright © 2016 John Wiley & Sons, Ltd.     

Crystal structure,shape analysis and bioactivity of new LiI,NaI and MgII complexes with 1,10‐phenanthroline and 2‐(3,4‐dichlorophenyl)acetic acid

Reactions of 1,10‐phenanthroline (phen) and 2‐(3,4‐dichlorophenyl)acetic acid (dcaH) with M_n(CO₃) (M = Li^I, Na^I and Mg^II; n = 1 and 2) in MeOH yield the mononuclear lithium complex aqua[2‐(3,4‐dichlorophenyl)acetato‐κO](1,10‐phenanthroline‐κ²N,N′)lithium(I), [Li(C₈H₅Cl₂O₂)(C₁₂H₈N₂)(H₂O)] or [Li(dca)(phen)(H₂O)] ( 1 ), the dinuclear sodium complex di‐μ‐aqua‐bis{[2‐(3,4‐dichlorophenyl)acetato‐κO](1,10‐phenanthroline‐κ²N,N′)sodium(I)}, [Na₂(C₈H₅Cl₂O₂)₂(C₁₂H₈N₂)₂(H₂O)₂] or [Na₂(dca)₂(phen)₂(H₂O)₂] ( 2 ), and the one‐dimensional chain magnesium complex catena‐poly[[[diaqua(1,10‐phenanthroline‐κ²N,N′)magnesium]‐μ‐2‐(3,4‐dichlorophenyl)acetato‐κ²O:O′] 2‐(3,4‐dichlorophenyl)acetate monohydrate], {[Mg(C₈H₅Cl₂O₂)(C₁₂H₈N₂)(H₂O)₂](C₈H₅Cl₂O₂)·H₂O}_n or {[Mg(dca)(phen)(H₂O)₂](dca)·H₂O}_n ( 3 ). In these complexes, phen binds via an N,N′‐chelate pocket, while the deprotonated dca^? ligands coordinate either in a monodentate (in 1 and 2 ) or bidentate (in 3 ) fashion. The remaining coordination sites around the metal ions are occupied by water molecules in all three complexes. Complex 1 crystallizes in the triclinic space group P with one molecule in the asymmetric unit. The Li⁺ ion adopts a four‐coordinated distorted seesaw geometry comprising an [N₂O₂] donor set. Complex 2 crystallizes in the triclinic space group P with half a molecule in the asymmetric unit, in which the Na⁺ ion adopts a five‐coordinated distorted spherical square‐pyramidal geometry, with an [N₂O₃] donor set. Complex 3 crystallizes in the orthorhombic space group P2₁2₁2₁, with one Mg²⁺ ion, one phen ligand, two dca^? ligands and three water molecules in the asymmetric unit. Both dcaH ligands are deprotonated, however, one dca^? anion is not coordinated, whereas the second dca^? anion coordinates in a bidentate fashion bridging two Mg²⁺ ions, resulting in a one‐dimensional chain structure for 3 . The Mg²⁺ ion adopts a distorted octahedral geometry, with an [N₂O₄] donor set. Complexes 1 – 3 were evaluated against urease and α‐glucosidase enzymes for their inhibition potential and were found to be inactive.