On Complex Formation between 5-Fluorouracil and β-Cyclodextrin in Solution and in the Solid State: IR Markers and Detection of Short-Lived Complexes by Diffusion NMR

In this work, the nuclear magnetic resonance (NMR) and IR spectroscopic markers of the complexation between 5-fluorouracil (5-FU) and β-cyclodextrin (β-CD) in solid state and in aqueous solution are investigated. In the attenuated total reflectance(ATR) spectra of 5-FU/β-CD products obtained by physical mixing, kneading and co-precipitation, we have identified the two most promising marker bands that could be used to detect complex formations: the C=O and C-F stretching bands of 5-FU that experience a blue shift by ca. 8 and 2 cm⁻¹ upon complexation. The aqueous solutions were studied by NMR spectroscopy. As routine NMR spectra did not show any signs of complexation, we have analyzed the diffusion attenuation of spin–echo signals and the dependence of the population factor of slowly diffusing components on the diffusion time (diffusion NMR of pulsed-field gradient (PFG) NMR). The analysis has revealed that, at each moment, ~60% of 5-FU molecules form a complex with β-CD and its lifetime is ca. 13.5 ms. It is likely to be an inclusion complex, judging from the independence of the diffusion coefficient of β-CD on complexation. The obtained results could be important for future attempts of finding better methods of targeted anticancer drug delivery.     

Novel highly sensitive Cu‐based SERS platforms for biosensing applications

Novel surface enhanced Raman spectroscopy (SERS) platforms have been prepared and used for the bacteria detection. Unlike typical, expensive SERS platforms prepared from gold or silver, the presented platforms are prepared using copper. A new, simple, cost‐efficient and fast high pressure method is used for platform fabrication, through the decomposition of copper hydride. The platform enhancement factors are verified using the malachite green isothiocyanate as a standard. The platforms exhibit extremely high SERS enhancement factors depending on pressure used for their preparation. The calculated enhancement factors have been found in the range between 1.5 × 10⁶ and 4.6 × 10⁷. The SERS spectra reproducibility is established both across a single platform and among different platforms. The average spectral correlation coefficient (Γ) has been calculated to be 0.82. Fully characterized SERS platforms have then been used for detecting Staphylococcus aureus bacteria. These novel platforms have great potential to become excellent tools for biological or medical diagnostics as an alternative to more common silver or gold SERS platforms. Copyright © 2015 John Wiley & Sons, Ltd.     

Outstanding Catalytic Activity of Ultra‐Pure Platinum Nanoparticles

Small (4 nm) nanoparticles with a narrow size distribution, exceptional surface purity, and increased surface order, which exhibits itself as an increased presence of basal crystallographic planes, can be obtained without the use of any surfactant. These nanoparticles can be used in many applications in an as‐received state and are threefold more active towards a model catalytic reaction (oxidation of ethylene glycol). Furthermore, the superior properties of this material are interesting not only due to the increase in their intrinsic catalytic activity, but also due to the exceptional surface purity itself. The nanoparticles can be used directly (i.e., as‐received, without any cleaning steps) in biomedical applications (i.e., as more efficient drug carriers due to an increased number of adsorption sites) and in energy‐harvesting/data‐storage devices.     

Succinonitrile Activated by Thiating Agents as Precursor of Bis-cyclic Amidines, Tectons for Molecular Engineering

Summary. Modification of the thio-Pinner’s method via in situ activation of a nitrile by thiating agents, S₈, P₄S₁₀, Lawesson reagent, or Na₂S·9H₂O, was applied in the syntheses of bis(4,5-dihydro-1H-imidazol-2-yl)alkanes and bis(1,4,5,6-tetrahydropyrimidin-2-yl)alkanes.     

Thermodynamic and physicochemical properties of binary mixtures of nitromethane with {2-methoxyethanol + 2-butoxyethanol} systems at T = (293.15, 298.15, 303.15, 308.15, and 313.15) K

The density, relative permittivity, viscosity and speed of sound at T = (293.15, 298.15, 303.15, 308.15, and 313.15) K in the binary mixtures of nitromethane with 2-methoxyethanol and 2-butoxyethanol have been measured as a function of composition. From the experimental results, the excess molar volumes V^E, excess Gibbs free energy of activation for viscous flow $(\mathrm{\Delta }{G}^{1E})$, excess isentropic compressibility $({\kappa }_s^E)$ and the deviations in the relative permittivity, viscosity, and speed of sound from a mole fraction average have been calculated. The viscosity data, at T = 298.15 K, were correlated with equations of Hind et al., Grunberg and Nissan, Frenkel, and McAllister. The results are discussed in terms of intermolecular interactions and structure of studied binary mixtures.     

Enantioseparation of Novel Amino Analogs of Indole Phytoalexins on Macrocyclic Glycopeptide-Based Chiral Stationary Phase

Direct chiral separation of the enantiomers of spirobrassinin, 1-methoxyspirobrassinin and ten novel cis- and trans-diastereoisomers of 2-amino analogs of indole phytoalexin 1-methoxyspirobrassinol methyl ether on macrocyclic glycopeptide-based chiral stationary phase (CSP) with teicoplanin (Chirobiotic T) was studied. Normal phase eluents containing n-hexane with modifiers ethanol and 2-propanol were used. The effects of mobile phase composition, structure of the analytes and temperature were investigated. Chiral resolution on teicoplanin CSP was achieved only in the case of trans-diastereoisomers. The van??t Hoff plots were found to show linear behavior in all cases. It was found that studied normal phase enantioseparations were enthalpy driven. The elution order of the enantiomers was determined in some cases.     

Oscillation quenching mechanisms: Amplitude vs. oscillation death

Oscillation quenching constitutes a fundamental emergent phenomenon in systems of coupled nonlinear oscillators. Its importance for various natural and man-made systems, ranging from climate, lasers, chemistry and a wide range of biological oscillators can be projected from two main aspects: (i) suppression of oscillations as a regulator of certain pathological cases and (ii) a general control mechanism for technical systems. We distinguish two structurally distinct oscillation quenching types: oscillation   (OD$OD$) and amplitude death   (AD$AD$) phenomena. In this review we aim to set clear boundaries between these two very different oscillation quenching manifestations and demonstrate the importance for their correct identification from the aspect of theory as well as of applications. Moreover, we pay special attention to the physiological interpretation of OD$OD$ and AD$AD$ in a large class of biological systems, further underlying their different properties. Several open issues and challenges that await further resolving are also highlighted.     

Soybean and Lupine Addition in Hen Nutrition—Influence on Egg Immunoreactivity

Modifying hen fodder is a common way of changing eggs composition today. However, there is no information on the effect of the source of protein in the fodder replacement on egg allergenicity. This research aimed to detect potential differences in the immunoreactivity and protein composition of eggs from hens fed with fodder containing legume. The aim of the first step of the study was to select the proper solvent for extracting allergenic proteins from hen eggs. Two of them (containing Tween 20 and Triton 100) were selected, based on protein profile and concentration analysis. Egg-white- and egg-yolk-proteins extracts prepared with them were checked for potential differences, using SDS-PAGE electrophoresis, and then the Western-blot method, using sera from children allergic to eggs and soy. Preliminary studies on the influence of fodder composition on the composition of egg proteins suggest that the addition of soy and lupine to fodder modifies the expression of egg proteins. The observed differences in the immunoreactivity of proteins contained in hen egg-white samples do not seem to be as significant as the appearance of protein with a molecular weight of ~13 kDa in the yolk of eggs obtained from soybean-fed hens. This protein may increase the immunoreactivity of eggs for children allergic solely to soy.     

Intramolecular N−H⋅⋅⋅F Hydrogen Bonding Interaction in a Series of 4-Anilino-5-Fluoroquinazolines: Experimental and Theoretical Characterization of Electronic and Conformational Effects

The 4-anilino-6,7-ethylenedioxy-5-fluoroquinazoline scaffold is presented as a novel model system for the characterization of the weak NH⋅⋅⋅F hydrogen bonding (HB) interaction. In this scaffold, the aniline NH proton is forced into close proximity with the nearby fluorine (d_H,F∼2.0 Å, ∠∼138°), and a through-space interaction is observed by NMR spectroscopy with couplings (^1hJ_NH,F) of 19±1 Hz. A combination of experimental (NMR spectroscopy and X-ray crystallography) and theoretical methods (DFT calculations) were used for the characterization of this weak interaction. In particular, the effects of conformational rigidity and steric compression on coupling were investigated. This scaffold was used for the direct comparison of fluoride with methoxy as HB acceptors, and the susceptibility of the NH⋅⋅⋅F interaction to changes in electron distribution and resonance was probed by preparing a series of molecules with different electron-donating or -withdrawing groups in the positions para to the NH and F. The results support the idea that fluorine can act as a weak HB acceptor, and the HB strength can be modulated through additive and linear electronic substituent effects.     

Green-, Red-, and Infrared-Emitting Polymorphs of Sterically Hindered Push–Pull Substituted Stilbenes

The synthesis, XRD single-crystal structure, powder XRD, and solid-state fluorescence of two new DPA-DPS-EWG derivatives (DPA=diphenylamino, DPS=2,5-diphenyl-stilbene, EWG=electron-withdrawing group, that is, carbaldehyde or dicyanovinylene, DCV) are described. Absorption and fluorescence maxima in solvents of various polarity show bathochromic shifts with respect to the parent DPA-stilbene-EWGs. The electronic coupling in dimers and potential twist elasticity of monomers were studied by density functional theory. Both polymorphs of the CHO derivative emit green fluorescence (527 and 550 nm) of moderate intensity (10 % and 5 %) in polycrystalline powder form. Moderate (5 %) red (672 nm) monomer-like emission was also observed for the first polymorph of the DCV derivative, whereas more intense (32 %) infrared (733 nm) emission of the second polymorph was ascribed to the excimer fluorescence.