Computational and Experimental Method for Evaluating the Reactivity of Substituted Toluene Diamines and Azo Compounds in the Reactions of Amine and Anhydride Curing of Epoxy Resins

Russian Journal of Applied Chemistry - The optimization of the molecular structure of substituted 3,5-toluylene diamines was carried out by the ab initio method, which made it possible to calculate...     

Synthesis and fluorescent properties of thiacalix[4]arenes containing terpyridyl fragments at the lower rim

New thiacalix[4]arenes tetrasubstituted by terpyridyl fragments at the lower rims in the 1,3-alternate stereoisomeric form were synthesized. The molecules interact with Eu^III and Tb^III in the DMF solution to form highly luminescent nanoscale (21–26 nm) metal-organic structures with the 2: 1 metal-to-ligand stoichiometry and a narrow particle size distribution.     

Structure–reactivity relationship in bimolecular elimination reactions based on the condensed graph of a reaction

By means of a structural representation of the chemical reactivity as a condensed graph a model predicting rate constants of the bimolecular elimination reaction is derived for the first time. The model developed enables the prediction of rate constants of reactions proceeding in different solvents or water-organic mixtures at different temperatures. It demonstrates a good predictive performance: a mean square deviation of predicted values from experimental ones is less than 0.7 logarithmic units. An outlier analysis shows that prediction errors are mainly due to the imperfection of the training data containing unique reactions. The model is available for users at arsole.u-strasbg.fr.     

Effect of copper(I) on the conformation of the thiacalixarene platform in azide-alkyne cycloaddition

New lower-rim tetrasubstituted p-tert-butylthiacalix[4]arene derivatives bearing alkyl, propargyl, or triazole-containing substituents were synthesized. The structures of these compounds were determined by 1D and 2D NMR spectroscopy in solution and by X-ray diffraction in the solid phase. The copper-catalyzed azide-alkyne cycloaddition (CuAAC) of azides to a mixture of 1,3-alternate–partial cone stereoisomers of dipropargyl derivatives of thiacalix[4]arene affords triazole-containing products exclusively in the 1,3-alternate conformation.     

Heat-Resistant Epoxy Polymers of Anhydride Curing

The interaction of UP-643 epoxy-novolac resin with isomethyltetrahydrophthalic anhydride in the presence of the catalysts (azo-compounds of different structure) is studied. Latency of the catalysts is found. The possibility is shown of creating epoxy binders with a long lifetime (10–40 days) at room temperatures, cured at increased temperature up to heat-resistant polymers.     

A Multichannel System for the Synchronous Recording of Processes during Thermoluminescence and Electroluminescence

Russian Journal of Physical Chemistry A - A version of a measuring system whose advantages include multifunctionality, simplicity, and availability of the main components is proposed. The system is...     

Elgctron Density Distribution and Intramolecular Dynayics in Phosphorane (Cl3C)2PCl3

Abstract

The trigonal-bipyramidal structure of phosphorane (Cl₃C)₂PCl₃ (I) with two non-equivalent axial Cl₃C-groups at the P atom was established by the X-ray diffraction method. At 293°K these groups are involved in independent libration around the longest molecular axis and some characteristics of these motions were estimated from diffraction data. Electron density distribution in I was studied at 153°K (λMo, ca. 7000 reflections, “high-angle” refinement to R=0.027 using 1310 reflections with sinθ/λ ≥ 0.70 A°^?1). At low temperature tile above-mentioned independent librations of the Cl₃C-groups become frozen, which is proved by the rigid-body analysis of the anisotropic thermal parameters of I, and also by the NQR ³⁵Cl spectral data. All chemical bonds in I are characterized by peaks of positive deformation electron density (DED). Positive DED peaks are also found near C1-atoms and attributed to the lone pairs of C1-atoms. Elongation of the P-C bonds (2.000 (2) and 1.992 (2) A°) is caused by electrostatic repulsion of the positively charged P and C atoms, whose charges were estimated from diffraction data. The character of the electron density distribution in I is in accordance with the generally accepted notion on the nature of chemical bonds in pentacovalent phosphoranes.     

Radial tetra(ferrocenyl)- and tetra(cymantrenyl)cyclobutadienecobalt complexes: Synthesis and structures

Novel radial tetra(ferrocenyl)- and tetra(cymantrenyl)cyclobutadienecobalt complexes were prepared by metal carbonyls free protocol of [2 + 2] cycloaddition reaction of 1,2-diferrocenyl- or 1,2-dicymantrenylethynes with chlorotris(triphenylphospine)cobalt(I) and carboethoxycyclopentadienide sodium with good yields. The molecular structure of these products was confirmed with X-ray analysis, and their electrochemical behavior was studied.