SIMULATION OF POLYMORPHIC VARIETIES OF HEXAGONAL GRAPHENE FUNCTIONALIZED BY HYDROXYL GROUPS

Моделирование кристаллической и электронной структуры слоев гексагонального графена, на поверхность которых были химически адсорбированы гидроксильные группы, было выполнено методом теории функционала плотности. В результате расчетов была установлена возможность устойчивого существования пяти структурных разновидностей COH - L слоев. Слоевая плотность изменяется от 1,62 до 1,72 мг/м. Длина водород-кислородной связи варьируется в диапазоне от 1,046 до 1,079 Å, а углерод-кислородной связи - от 1,455 до 1,465 Å. Ориентация O - H связей относительно плоскости слоев может варьироваться в зависимости от выбора элементарной ячейки слоя. Минимальной энергией сублимации и равной 18,69 эВ/(COH) обладает слой COH-L - T4, а максимальную энергию сублимации 18,93 эВ/(COH) имеет слой COH - L - T1. Электронная структура всех COH слоев характеризуется наличием прямой запрещенной зоны на уровне энергии Ферми, изменяющейся в диапазоне от 3,02 до 4,56 эВ. Computer simulation of the crystal and electronic structure of hexagonal graphene layers, on the surface of which hydroxyl groups, chemically adsorbed, was performed by the density functional theory method. As a result of calculations, the possibility of the stable existence of five structural varieties of COH - L layers was established. The layer density varies from 1,62 to 1,72 mg/m. The length of the hydrogen-oxygen bond varies in the range from 1,046 to 1,079 Å, and the carbon-oxygen bond-from 1,455 to 1,465 Å. The orientation of the -OH bonds relative to the surface of the layers can vary depending on the choice of the unit cell of the layer. Layer COH - L - T4 has the minimum sublimation energy equal to 18,69 eV/(COH), and layer COH - L - T1 has the maximum sublimation energy 18,93 eV/(COH). The electronic structure of all COH layers is characterized by the presence of a direct band gap at the Fermi energy level, varying in the range from 3,02 to 4,56 eV.

Photocatalytic Alkylation of α-(Trifluoromethyl)Styrenes with Potassium Xanthogenates

A protocol for the coupling of potassium xanthogenates with α-(trifluoromethyl)styrenes in the presence of triethyl phosphite is reported. The reaction is carried out under blue light irradiation in the presence of organic photocatalyst 3DPAFIPN. The reaction proceeds via formation of alkyl radicals from readily available xanthogenate salts via oxidative desulfurization and cleavage of the carbon–oxygen bond assisted by triethyl phosphite.

Oxidation Modification of Fuorinated Graphite and Its Reaction Mechanism

In this paper, Hummers method was used to oxidize fluorinated graphite in order to study the modification mechanism. The chemical composition and microstructure of the products before and after the reaction were characterized and analyzed. Oxidized fluorinated graphite (OFG) obtained by oxidation has a thin layered structure and different oxygen content. The main mechanism of KMnO4 modification is that MnO3+ with Lewis acid property can catalyze the activation of the fluorocarbon bond, which breaks to form F ion. At the same time, the unsaturated carbon bond is oxidized, resulting in the increase of carbon oxygen bond content and the generation of some OFG nano fragments. With the increase in KMnO4 dosage, the fluorocarbon bond will be gradually catalyzed to react according to its activity while the unsaturated carbon bond is oxidized, finally there are still some isolated fluorocarbon bonds with weak activity.