Interfacial behavior of water bound to nitrocellulose containing residual nitric and sulfuric acids

To prepare nitrocellulose (NC), microcrystalline cellulose was treated in a mixture of nitric and sulfuric acids. Prepared NC containing a small amount of acids was studied at a different hydration degree (h = 10–1000 mg g^?1) in different dispersion media (chloroform-d, acetone-d₆ or their mixtures) using low-temperature ¹H NMR spectroscopy. The hydration degree and the presence of residual acids affected the temperature dependence of the chemical shifts of proton resonance of water bound to NC. The Gibbs free energy of bound water became less negative with increasing hydration rate. The chloroform and acetone media affect the behavior of bound-to-NC water unfrozen at T<273 K differently. Quantum chemical calculations were performed using ab initio (HF/6-31G(d,p)), DFT (B3LYP/6-31G(d,p)) and semiempirical PM7 methods to analyze the interfacial behavior of water interacting with NC containing residual amounts of nitric and sulfuric acids.      

On the aronszajn property for a differential equation of fractional order in Banach spaces

In this paper we investigate some topological properties of solution sets of a differential equation of fractional order in Banach spaces. Our assumptions and proofs are expressed in terms of measures of noncompactness.     

Intermolecular interactions in mixtures of dichroic dyes with n-alkyl-4-(4-isothiocyanatophenyl)bicyclo[2,2,2]octanes

On the basis of the polarized absorption spectra, the guest order parameter as a function of temperature for five dichroic azo dyes dissolved in four members (pentyl to octyl) of the homologous series of n-alkyl-4-(4-isothiocyanatophenyl)bicyclo[2,2,2]octanes has been evaluated. Moreover, the influence of the dichroic dye addition on the nematic-isotropic phase transition temperature has been examined. The relation between the molecular geometry of the guest, its orientation efficiency in the nematic host and the clearing temperature of the azo dye-liquid crystal mixtures has been determined. The experimental results have been compared in some detail with calculations performed on the basis of the mean field theory for binary mixtures.     

EPR spectra of gamma-irradiated DL-alpha-alanine supported on molecular sieves

The aim of the work was to collect information concerning boundary effects which are suspected in alpha-alanine dosimeters consisted of powdered microcrystalline alpha-alanine and binders. In our experiments the conventional binders were replaced by molecular sieves (MS). MS are inorganic porous materials (host structures) with well organized and uniform intra-crystalline pore systems of nano-scale size. The guest molecules can be either physically adsorbed on very large inner MS surface, or chemically bound to the active sites. They can be also encapsulated inside the intracrystalline cavities. The EPR spectra of gamma irradiated DL-alpha-alanine supported on NaY, CeY, SOD, mordenite, ZSM-5 and ALPO(4)-5 were very similar to that one observed for irradiated microcrystalline DL-alpha-alanine. In the case of alanine supported on HY an initial EPR spectrum was different and only after some weeks it made resemble to the well known quintet observed in microcrystalline samples. In sodalites synthesized in the presence of DL-alpha-alanine EPR signal appeared in non-irradiated sample was very low and structureless. The irradiated sample showed a distinct spectrum which was quite different from that one observed for crystalline DL-alpha-alanine.     

Sulfur radicals embedded in various cages of ultramarine analogs prepared from zeolites

The colored (greenish) products analogous to ultramarine obtained from zeolite A, cancrinite and erionite by means of high-temperature (500-800 °C) treatment of zeolites mixed with elemental sulfur and alkalis can maintain the original structure of the parent zeolite under certain preparation conditions. The ESR spectra of samples recorded at room temperature always indicate the presence of radicals S₃⁻ (the blue chromophore). The spectra of samples prepared from zeolites recorded at 77 K exhibit additional signals that could be assigned to the yellow chromophore (the radical S₂⁻) encapsulated inside the β or ε-cages. It is remarkable that in the case of products with preserved cancrinite structure, where the S₂⁻ radicals are encapsulated inside the ε-cages, the above signals are visible already at room temperature. It may result from retarded mobility of these species in small cancrinite cages.     

Study of the role of ceramic filler in composite gel electrolytes based on microporous polymer membranes

The presented contribution aims at reconsidering the role of filler in affecting the ionic transport in composite gel electrolytes for Li-ion cells based on microporous polymer membranes. The gels have been prepared by swelling thin PVdF/HFP membranes either with conventional liquid electrolyte or with pure propylene carbonate solvent. The membranes contained dispersed submicron-size modified silica filler added in a wide range of weight ratios. The effect of filler content on the kinetics of liquid phase absorption and evaporation from the composite membranes, as well as on the conductivity of the corresponding gel electrolytes, has been studied and discussed in terms of the “colloidal” and “soggy sand” electrolyte concepts. It has been found that conductivity increase of composite gels is not directly correlated with the liquid electrolyte uptake. On this basis it is concluded that important part of ionic transport in this type of composite gel polymer electrolytes is realized on the filler grain boundaries, through overlapping space charge layers of the silica grains.     

α-Alkyl(aryl)sulfenyl substituted β-ketophosphonates: synthesis, properties and reactivity

A new synthesis of the title compounds via acylation of α-lithio-α-phosphorylalkyl sulfides is described. Two additional approaches to these compounds, although less efficient, involve: (a) sulfenylation of O-silylated dialkyl β-ketophosphonates and (b) the Arbuzov reaction of triethyl phosphite with α-chloro-α-methylthiomethyl phenyl ketone. The keto-enol tautomerism of the title compounds and reactivity of the anions derived from them with electrophilic reagents were investigated. The P(O)-olefination products obtained from electron rich aromatic aldehydes were found to undergo the acid-catalyzed desulfenylation reaction affording α,β-unsaturated ketones.     

The unusual course of the high-pressure reaction of 1,10-diaza-[18]-crown-6 with α,ω-diiodo ethers

Simple 1,10-diaza-[18]-crown-6 reacts smoothly with di(2-indoethyl)ether under high-pressure (10 kbar) to give a bis-quaternary spiro salt as a major product, whereas the analogous reaction with 1,8-diiodo-3,6-dioxaoctane leads to the expected precursor of a [2.2.2] cryptand.     

Mesomorphic Properties of New 5-Alkyl-2-Pyrimidinols Esters

Abstract

A synthesis of a number of 5-alkyl-2-pyrimidinol esters was conducted, their mesomorphic properties were examined. Two ring esters of said pyrimidinols are nonmesomorphic, while three ring esters are typical mesogens, forming nematic either nematic-smectic mesophases.