Rational Design of a Porous Supramolecular Peptide Framework (SPF): A Crystalline Tetraproline in the Polyproline II Conformation

Herein, we present the first high resolution single crystal structure of an unfunctionalized tetrameric proline in the poly-proline II conformation. This rationally designed oligoproline tetramer, self-assembles to form a permanently porous crys-talline supramolecular peptide framework (SPF). Thermal activation, guest inclusion and thermally induced release of chemical guests have been demonstrated for this novel system. This discovery provides a conclusive insight into the pre-viously ambiguous conformation of short oligoprolines and will allow for the further development of proline-based pep-tide linkers in the rational design of SPFs and metal-peptide frameworks.

The features of deformation-stimulated RbI luminescence

This paper studies deformation-stimulated features of radiative relaxation of self-trapped excitons and recombination assembly of exciton-like luminescence in RbI crystal. Methods of research were luminescence and thermal activation spectroscopy. The identity of the mechanism of manifestation of the X-ray luminescence, tunnel luminescence and thermally stimulated luminescence spectra were found in the elastically deformed RbI crystal, interpreted by the luminescence of self-trapped exciton, tunnel recharge of F′, VK -pairs and thermally stimulated recombination of e−, VK -centres, respectively.The temperatures of the maximum destruction peaks of thermally stimulated luminescence, their spectral composition and activation energies were determined experimentally, on the basis of which the mechanisms of recombination assembly of exciton-like luminescences in a RbI crystal were interpreted. Uniaxial elastic deformation leads to the effective formation of point radiation defects ( F′, HA, VK -centers) in comparison with an unbroken lattice, where the predominant mechanism is the association of interstitial atoms ( H -centres) with the formation of I3−-centres.

Aluminum Oxide Catalysts and Supports Obtained by Thermal Activation

The paper considers the main methods used to obtain aluminum oxides; the advantages of using hydrargillite thermal activation products for the synthesis of catalysts, supports and sorbents; the factors affecting the properties of thermal activation products and aluminum oxides obtained by thermal activation; and examples of the efficient application of hydrargillite centrifugal thermal activation products in the synthesis of catalysts, supports and sorbents.

Thermal Activation of Kaolin: Effect of Kaolin Mineralogy on the Activation Process

Kaolin is an industrial mineral used in a wide variety of applications due to its crystalline structure, mineral and elemental composition. After kaolin undergoes heat treatment in a specific temperature range, metakaolin, which exhibits a strong pozzolanic reaction, is formed. This paper examines the effects of different kaolin qualities on the thermal activation process of metakaolin production. The qualities of kaolin depend on the impurities they contain, such as mica, feldspar and quartz. In this study, four different samples of kaolin are investigated. Each sample was heat treated in a lab-scale rotary kiln in order to study the chemical, structural and morphological changes that occurred and their influence on pozzolanic activity. The parameters being considered in the experimental process were the temperature and the duration of the treatment. Thus, the calcination process for each of the four kaolin types was carried out at 600, 650 and 700 °C for 3 h. The occurred changes were monitored using XRD, FTIR and DTA analysis. Additionally, the reactivity of all thermally treated samples was evaluated based on the Chapelle test. The results showed that the fewer the impurities, the easier the transformation of the material to metakaolin. The optimum result was the metakaolin, which originated from the purest quality of kaolin and was comparable to the commercial product. Finally, the pozzolanic activity of the thermally activated samples also depended on the purity of the kaolin.

Reactions of 1-trifluoromethyl-propyne 1-iminium salts with nitroanilines: synthesis of 4-CF3-nitroquinolines and 1,2,3-trisubstituted-5-CF3-pyrroles

A variety of 4-CF3-quinolines bearing an aryl (or cyclopropyl, tert-butyl, trimethylsilyl) group at C-2 and a nitro group at ring position 6, 7 or 8 have been prepared in good to high yields from 3-substituted 1-CF3-prop-2-yne 1-iminium triflate salts and o-, m- or p-nitroaniline. These reactions include an aza-Michael reaction at room temperature followed by an intramolecular electrophilic aromatic substitution step, which requires additional thermal activation in most cases. In contrast, the conjugate addition of 2,4-dinitroanilines at the acetylenic iminium ions proceeds much more slowly and some of the adducts can be converted thermally into 2-(2,4-dinitrophenyl)-5-CF3-pyrroles. Analogously, 2-(4-pyridyl)-5-CF3-pyrroles were obtained from 3-aryl-1-CF3-propyne iminium salts and 4-aminopyridinium triflate. A novel variation of the Truce-Smiles rearrangement is probably involved in the formation of these pyrroles.