Electrocatalytic Nanostructured Ferric Tannates: Characterization and Application of a Polyphenol Nanosensor

A novel core–shell hybrid nanomaterial composed of peculiar maghemite nanoparticles (surface‐active maghemite nanoparticles (SAMNs)) as the core and tannic acid (TA) as the shell was developed by self‐assembly of ferric tannates onto the surface of SAMNs by simple incubation in water. The hybrid nanomaterial (SAMN@TA) was characterized by using UV/Vis, FTIR, and Mössbauer spectroscopies, magnetization measurements, and X‐ray powder diffraction, which provide evidence of a drastic reorganization of the iron oxide surface upon reaction with TA and the formation of an outer shell that consists of a cross‐linked network of ferric tannates. According to a Langmuir isotherm analysis, SAMN@TA offers one of most stable iron complexes of TA reported in the literature to date. Moreover, SAMN@TA was characterized by using electrical impedance spectroscopy, voltammetry, and chronoamperometry. The nanostructured ferric tannate interface showed improved conductivity and selective electrocatalytic activity toward the oxidation of polyphenols. Finally, a carbon‐paste electrode modified with SAMN@TA was used for the determination of polyphenols in blueberry extracts by square‐wave voltammetry.     

Sandwich Fibrous PEG Encapsulations for Thermal Energy Storage

Phase change materials (PCMs) textiles have been developed for personal thermal management (PTM) while limited loading amount of PCMs in textiles reduced thermal buffering effect. In this work, we proposed a sandwich fibrous encapsulation to store polyethylene glycol (PEG) with PEG loading amount of 45 wt %, which consisted of polyester (PET) fabrics with hydrophobic coating as protection layers, polyurethane (PU) nanofibrous membranes as barrier layers and PEG-loaded viscose fabric as a PCM-loaded layer. The leakage was totally avoided by controlling weak interfacial adhesion between protection layer and melting PEG. The sandwich fibrous PEG encapsulations had an overall melting enthalpy value ranging from 50 J/g to 78 J/g and melting points ranging from 20 °C to 63 °C by using different PEGs. Besides, introduction of Fe microparticles in PCM-loaded layer enhanced thermal energy storage efficiency. We believe that the sandwich fibrous PEG encapsulation has a great potential in various fields.     

Thioimides: new reagents for effective synthesis of thiolesters from carboxylic acids

Thioimides and carboxylic acids are used as the precursors for the convenient synthesis of thiolesters in the phosphine mediated process. Cyclic and acyclic thioimides show equal efficiency, furnishing the desired thiolesters in good to excellent yields. The general, highly efficient transformation tolerates various functional groups and the resulting thiolesters are obtained in high purity after a simple separation. The reaction scope has been demonstrated on the preparation of several highly functionalized target molecules.     

The length of esterifying alcohol affects the aggregation properties of chlorosomal bacteriochlorophylls

Abstract Chlorosomes, the main light-harvesting complexes of green photosynthetic bacteria, contain bacteriochlorophyll (BChl) molecules in the form of self-assembling aggregates. To study the role of esterifying alcohols in BChl aggregation we have prepared a series of bacteriochlorophyllide c (BChlide c) derivatives differing in the length of the esterifying alcohol (C(1), C(4), C(8) and C(12)). Their aggregation behavior was studied both in polar (aqueous buffer) and nonpolar (hexane) environments and the esterifying alcohols were found to play an essential role. In aqueous buffer, hydrophobic interactions among esterifying alcohols drive BChlide c derivatives with longer chains into the formation of dimers, while this interaction is weak for BChlides with shorter esterifying alcohols and they remain mainly as monomers. All studied BChlide c derivatives form aggregates in hexane, but the process slows down with longer esterifying alcohols due to competing hydrophobic interactions with hexane molecules. In addition, the effect of the length of the solvent molecules (n-alkanes) was explored for BChl c aggregation. With an increasing length of n-alkane molecules, the hydrophobic interaction with the farnesyl chain becomes stronger, leading to a slower aggregation rate. The results show that the hydrophobic interaction is the driving force for the aggregation in an aqueous environment, while in nonpolar solvents it is the hydrophilic interaction.     

Limiting activity coefficients in binary mixtures of 1-alkanols and ethylbenzene

Limiting activity coefficients in binary mixtures of six lower 1-alkanols (C₁–C₆) and ethylbenzene were determined employing alternatively the techniques of inert gas stripping and comparative ebulliometry. For each case, the suitable technique was chosen on the basis of the limiting relative volatility of the solute. Measurements were typically carried out at four temperatures covering a range of 30 K and were done with a good precision (1–3%). The new data were compared with available literature information on both the activity coefficient and calorimetric partial molar excess enthalpy at infinite dilution. All the critically evaluated information was merged and processed simultaneously to produce the recommended temperature dependences of the limiting activity coefficients. The performance of leading prediction methods (UNIFAC, modified UNIFAC, ASOG, MOSCED, DISQUAC) was further examined using this data.     

Performance of the DFT-D method, paired with the PCM implicit solvation model, for the computation of interaction energies of solvated complexes of biological interest

In this work we investigate the performance of the DFT method, augmented with an empirical dispersion function (DFT-D), paired with the PCM implicit solvation model, for the computation of noncovalent interaction energies of biologically-relevant, solvated model complexes. It is found that this method describes intermolecular interactions within water and ether (protein-like) environments with roughly the same accuracy as in the gas phase. Another important finding is that, when environmental effects are taken into account, the empirical dispersion term associated with the DFT-D method need be modified very little (or not at all), in order to obtain the optimum, most well balanced, performance.     

Synthesis and structure of lanthanide complexes with large-bite diphosphine dioxide ligands

Three large-bite diphosphine dioxide ligands were reacted with lanthanide salts to yield either molecular or polymeric complexes. The two flexible ligands gave bischelate complexes of general formulae [Ln(dppfO₂)₂Cl_x(NO₃)_2−x][FeCl₄] and [Ln(dppdO₂)₂(NO₃)₂]NO₃, where dppfO₂ and dppdO₂ are bis(diphenylphosphoryl)ferrocene and bis(diphenylphosphoryl)diphenyl ether, respectively. Reactions of the rigid bis(diphenylphosphoryl)benzene (dppbO₂) with lanthanide salts yielded linear coordination polymers of a 1:1.5 metal-to-ligand stoichiometry. The compounds were studied by single crystal X-ray diffraction, IR spectroscopy, mass spectrometry, and TG/DSC techniques.     

Plastic plasma interaction with plasmas with growing atomic number

This paper describes the investigation of the influence of target material atomic number (Z) on the laser-produced plasma pressure. For this reason, several target materials representing a wide range of atomic numbers (Z = 3.5 - 73), i.e. plastic (CH), Al, Cu, Ag, and Ta, were used. The results presented show that the plasma pressure decreases with growing atomic number but in a limited range of Z only. For higher Z, starting approximately from Z = 47 (Ag), the plasma pressure becomes constant, as confirmed by interferometric measurements and x-ray plasma imaging.