Phosphorylation of Acetylaminophenols with Secondary Phosphine Chalcogenides: Synthesis of O-(Acetylamino)phenyl Chalcogenophosphinates

Russian Journal of General Chemistry - Oxidative cross-coupling of 4-acetylaminophenol (paracetamol) and its structural isomers (2- and 3-acetylaminophenols) with secondary phosphine chalcogenides...     

Synthesis of Linear and V-Shaped Carbazolyl-Substituted Pyridine-3,5-dicarbonitriles Exhibiting Efficient Bipolar Charge Transport and E-Type Fluorescence

With the aim of developing all-organic bipolar semiconductors with high charge mobility and efficient E-type fluorescence (so-called TADF) as environmentally friendly light-emitting materials for optoelectronic applications, four noble metals-free dyes with linear and V-shapes were designed using accepting pyridine-3,5-dicarbonitrile and donating carbazole units. By exploiting a donor-acceptor design strategy and using moieties with different donating and accepting abilities, TADF emitters with a wide variety of molecular weights were synthesized to achieve the optimum combination of charge-transporting and fluorescent properties in one TADF molecule. Depending on molecule structures, different TADF emitters capable of emitting in the range from 453 to 550 nm with photoluminescence quantum yields up to 98 % for the solutions in oxygen-free toluene were obtained. All compounds showed bipolar charge-transport. Hole mobility of 2.8×10⁻³ cm²/Vs at 7×10⁵ V cm⁻¹ was observed for the compound containing two di-tert-butyl-substituted carbazole moieties. The compounds were tested in both non-doped and doped organic light-emitting diodes using different hosts. It was shown that the developed TADF emitters are suitable for different color devices with electroluminescence ranging from blue to yellow and with brightness, maximum current and external quantum efficiencies exceeding 10 000 cd m⁻², 15 cd/A, and 7 %, respectively.     

An importance sampling procedure for estimating failure probabilities of non-linear dynamic systems subjected to random noise

The first passage problem for linear and non-linear oscillators excited by white and coloured noise are considered. An iterative variance reduction scheme is used in a framework of a measure change in the space of sample functions according to the Girsanov transformation, which is based on introducing a Markov control process. It is proved that a good approximation to the optimal stochastic control process can be obtained from an equivalent white noise excited linear oscillator. It is shown that this leads to very accurate estimates of the failure probability of the original system. The advantage of this procedure is that expressions for the parameters of the equivalent linear system and the design point oscillations, which are needed to find the control process, are available analytically. The number of samples, the variance of the failure probability estimates and the computational time are reduced significantly compared with direct Monte Carlo simulations.     

Laser–induced thermocapillary deformation of a thin liquid layer

An equation that describes the profile of laser–induced thermocapillary deformation of the thin layer of an absorbing liquid is obtained. Numerical estimates of the deformation profile are in agreement with experimental data. It is shown that with increase in the radiation power, the deformation depth of the liquid layer increases and leads to its rupture.     

3-Polyfluoroalkyl-1,5-diphenylpyrazoles in Suzuki Cross-Coupling Reactions

Russian Journal of Organic Chemistry - Suzuki cross-coupling was used for modification of 3-polyfluoroalkyl-1-phenylpyrazoles at the position C4. The synthesized 4-bromo- and 4-phenyl derivatives...     

Study of melanin localization in the mature male Calopteryx haemorrhoidalis damselfly wings

Damselflies Calopteryx haemorrhoidalis exhibiting black wings are found in the western Mediterranean, Algeria, France, Italy, Spain and Monaco. Wing pigmentation is caused by the presence of melanin, which is involved in physiological processes including defence reactions, wound healing and sclerotization of the insect. Despite the important physiological roles of melanin, the presence and colour variation among males and females of the C. haemorrhoidalis species and the localization of the pigment within the wing membrane remain poorly understood. In this study, infrared (IR) microspectroscopy, coupled with the highly collimated synchrotron IR beam, was employed in order to identify the distribution of the pigments in the wings at a high spatial resolution. It was found that the melanin is localized in the procuticle of the C. haemorrhoidalis damselfly wings, distributed homogeneously within this layer, and not associated with the lipids of the epicuticle.     

Synthesis of functionally substituted benzaldehydes

A new method of synthesis of functionally substituted benzaldehydes by catalytic debromometoxylation of dibromomethylarenes with benzaldehyde dimethyl acetal has been suggested. Anhydrous zinc chloride has been used as a catalyst. Being soft Lewis acid, it formed no strong complex with aldehyde group and other functional groups. The initial acetal has been readily recovered by the treatment of benzaldehyde isolated from the reaction mixture with trimethyl orthoformate.