Michael addition of phenylacetonitrile to the acrylonitrile group leading to diphenylpentanedinitrile. Structural data and theoretical calculations

Knoevenagel condensation of phenylacetonitrile with 4-diphenylaminophenylacetonitrile in the presence of piperidine was carried out to obtain a novel conjugated compound. In addition to the expected compound 2-(phenyl)-3-(4-diphenylaminophenyl)acrylonitrile (I), the 3-((4-diphenylamino)phenyl)-2,4-diphenylpentanedinitrile (II) was also obtained with a good yield. Compound II was obtained as a result of the Michael addition of phenylacetonitrile with 2-(phenyl)-3-(4-diphenylaminophenyl)acrylonitrile (I). Conversely, when the same reaction was performed in the presence of KOH as catalyst, only the α,β-unsaturated nitrile (I) was afforded with a 92 % yield. The structures were confirmed with IR, EI-MS and NMR spectroscopy. Single crystals I and II were formed and their structures were determined by X-ray single-crystal diffraction analysis. Crystal I belongs to the monoclinic system with space group P2₁/n having unit cell parameters of a = 16.8589(5) Å, b = 6.68223(17) Å, c = 19.8289(7) Å, β = 111.133(4)○ and Z = 4. Crystal II belongs to the same monoclinic system with space group P2₁/c, having unit cell parameters of a = 10.8597(4) Å, b = 24.7533(10) Å, c = 9.7832(4) Å, β = 91.297(3)○ and Z = 4. In addition to the structural data analysis, some theoretical calculations that reveal the nature of relevant structure-property relationships are also reported.     

Processing additives for improved efficiency from bulk heterojunction solar cells

Two criteria for processing additives introduced to control the morphology of bulk heterojunction (BHJ) materials for use in solar cells have been identified: (i) selective (differential) solubility of the fullerene component and (ii) higher boiling point than the host solvent. Using these criteria, we have investigated the class of 1,8-di(R)octanes with various functional groups (R) as processing additives for BHJ solar cells. Control of the BHJ morphology by selective solubility of the fullerene component is demonstrated using these high boiling point processing additives. The best results are obtained with R = Iodine (I). Using 1,8-diiodooctane as the processing additive, the efficiency of the BHJ solar cells was improved from 3.4% (for the reference device) to 5.1%.     

Noncovalent interactions under extreme conditions: high-pressure and low-temperature diffraction studies of the isostructural metal-organic networks (4-chloropyridinium)2[CoX4] (X = Cl, Br)

The crystal structures of the two isostructural metal-organic salts, (4-chloropyridinium) 2[CoX 4], X = Cl ( 1), Br ( 2), have each been determined at nine temperatures from 30 to 300 K and at nine pressures from atmospheric pressure to 4.2 GPa. A 5% reduction in unit cell volume is observed upon temperature reduction, whereas an 18-19% reduction is observed upon increasing the pressure over the ranges studied. The structures adopt a tape arrangement propagated by bifurcated N-H...X 2Co hydrogen bonds and by Co-X...Cl-C halogen bonds. Intertape interactions include type I Co-X...Cl-C and C-Cl...Cl-C halogen-halogen interactions as well as offset pi-stacking between the aromatic rings of the cations. Although little anisotropy in compression is seen upon temperature reduction, marked anisotropy in compression is observed upon pressure increase. Compression between tapes far exceeds compression along the tape, consistent with the strong attractive nature of the intratape N-H...X 2Co and Co-X...Cl-C interactions and the weaker dispersion dominated Co-X...Cl-C and C-Cl...Cl-C halogen-halogen interactions and pi-stacking interactions. Increased distortion of the [CoX 4] (2-) anions from idealized tetrahedral geometry arises upon pressure increase, consistent with local changes in the electric field that result from compression of the pairs of pi-stacked cations. The study of the isostructural pair of compounds permits a rare opportunity for quantitative evaluation of the "internal" or "chemical" pressure exerted by changing the [CoBr 4] (2-) anion for the smaller [CoCl 4] (2-) anion. Thus, crystal structures of 1 and 2 with equivalent unit cell volumes require an additional pressure of ca. 1 GPa exerted upon the structure containing the larger [CoBr 4] (2-) anion ( 2). This internal pressure increases to ca. 1.9 GPa at the highest pressures used in this study. Most significant is that examination of the isovolumetric pairs of structures shows that the structures containing the [CoCl 4] (2-) anion are contracted along the <101> vector, the direction of tape propagation, by ca. 1.2% and correspondingly expanded in other directions, relative to those containing the [CoBr 4] (2-) anion. Since the effect of difference in anion size has been removed by application of pressure, this anisotropy in dimensions clearly indicates that the N-H...X 2Co hydrogen bonds and Co-X...Cl-C halogen bonds are more strongly attractive for X = Cl rather than X = Br. Use of internal pressure thereby provides unique insight into the relative strength of intermolecular interactions.     

Reaction of arylhydrazines with an α-alkynyl-carbonylic compound: an unexpected hydration reaction

The acid catalyzed reactions of three arylhydrazines with 4-phenyl-3-butynone in order to obtain the corresponding arylhydrazone were realized. The arylhydrazone reaction and an unexpected alkyne hydration reaction product were obtained when diphenylhydrazine was used. This product was identified by spectroscopic methods and X-ray diffractogram. A reaction mechanism is proposed for its formation.     

The shape of $$ \mathbb {Z}/\ell \mathbb {Z}$$-number fields

Let \(\ell \) be a prime and let \(L/ \mathbb {Q}\) be a Galois number field with Galois group isomorphic to \( \mathbb {Z}/\ell \mathbb {Z}\). We show that the shape of L, see Definition 1.2, is either \(\frac{1}{2}\mathbb {A}_{\ell -1}\) or a fixed sub-lattice depending only on \(\ell \); such a dichotomy in the value of the shape only depends on the type of ramification of L. This work is motivated by a result of Bhargava and Shnidman, and a previous work of the first named author, on the shape of \( \mathbb {Z}/3 \mathbb {Z}\) number fields.     

Magnetic resonance study of a vanadium pentoxide gel

In this work we report results from continuous-wave (CW) and pulsed electron paramagnetic resonance (EPR) and proton nuclear magnetic resonance (NMR) studies of the vanadium pentoxide xerogel V₂O₅:nH₂O (n ≈ 1.6). The low temperature CW-EPR spectrum shows hyperfine structure due to coupling of unpaired V⁴⁺ electron with the vanadium nucleus. The analysis of the spin Hamiltonian parameters suggests that the V⁴⁺ ions are located in tetragonally distorted octahedral sites. The transition temperature from the rigid-lattice low-temperature regime to the high temperature liquid-like regime was determined from the analysis of the temperature dependence of the hyperfine splitting and the V⁴⁺ motional correlation time. The Electron Spin Echo Envelope Modulation (ESEEM) data shows the signals resulting from the interaction of ¹H nuclei with V⁴⁺ ions. The modulation effect was observed only for field values in the center of the EPR absorption spectrum corresponding to the single crystals orientated perpendicular to the magnetic field direction. At least three protons are identified in the xerogel by our magnetic resonance experiments: (I) the OH groups in the equatorial plane, (ii) the bound water molecules in the axial V=O bond and (iii) the free mobile water molecules between the oxide layers. Proton NMR lineshapes and spin-lattice relaxation times were measured in the temperature range between 150 K and 323 K. Our analysis indicates that only a fraction of the xerogel protons contribute to the measured conductivity.     

Rapid classification of enzymes in cleaning products by hydrolysis, mass spectrometry and linear discriminant analysis

A method for the rapid classification of proteases, lipases, amylases and cellulases used as enhancers in cleaning products, based on precipitation with acetone, hydrolysis with HCl, dilution of the hydrolysates with ethanol, and direct infusion into the electrospray ion source of an ion-trap mass spectrometer, has been developed. The abundances of the ([M+H]+ ions of the amino acids, from the hydrolysates of both the enzyme industrial concentrates and the detergent bases spiked with them, were used to construct linear discriminant analysis models, capable of distinguishing between the enzyme classes. For this purpose, the variables were normalized as follows: (A) the ion abundance of each amino acid was divided by the sum of the ion abundances of all the amino acids in the corresponding mass spectrum; (B) the ratios of pairs of ion abundances were obtained by dividing the ion abundance of each amino acid by each one of the ion abundances of the other 17 amino acids in the corresponding mass spectrum. Using normalization procedure B, excellent class-resolution between proteases, lipases, amylases and cellulases was achieved. In all cases, enzymes in industrial concentrates and manufactured cleaning products were correctly classified with >98% assignment probability.     

Steric impediment of alkyl groups in the nitrosation of alkylureas

The oxygenation constants and thermodynamic parameters (ΔH^o, ΔS^o) of a series of novel Co(II) dihydroxamic acids containing a central functional group (-OCH₃) CoL¹∼CoL⁶ were measured, their catalytic performance in the oxidation of p-xylene to p-toluic acid (PTA) were examined. The influence of` ligand structure, the substituents (X = Cl, OCH₃ and Y = H, CH₃, Cl) of the aromatic rings and added alkaline cations on the O₂-binding capabilities and catalytic oxidation activities were investigated.     

Classification of vegetable oils according to their botanical origin using sterol profiles established by direct infusion mass spectrometry

A simple and quick method to classify vegetable oils according to their botanical origin, based on direct infusion of sterol extracts into a mass spectrometer, was developed. Using mass spectrometry (MS) with either an electrospray ionization or an atmospheric pressure photoionization source, followed by linear discriminant analysis of the mass spectral data, oil samples corresponding to eight different botanical origins were perfectly classified with an excellent resolution among all the categories. An excellent correlation between the sterol profiles obtained by MS and by the official gas chromatography (with flame ionization detection) method was obtained. Thus, the proposed method is a promising alternative for sterol fingerprinting of vegetable oils, with the advantage that prior chromatographic separation is not required.