Asymmetric synthesis and molecular docking study of enantiomerically pure pyrrolidine derivatives with potential antithrombin activity

The (2R,4R,5S)- and (2S,4S,5R)-enantiomers of 4-(tert-butyl) 2-methyl 5-(4-bromophenyl)-pyrrolidine-2,4-dicarboxylate 3 were synthesized efficiently with an ee of >90% on a gram scale using a FAM-catalytic methodology. Subsequent modification afforded enantiopure N-((4-chlorophenyl)thio)acetyl pyrrolidine derivatives 4, which are potential thrombin inhibitors according to comprehensive molecular docking studies.     

The rotation of the polarization plane of quantum-well heterolasers emission under the ultrasonic strain

The paper is devoted to an acousto-electron effect in the nanodimensional laser heterostructures. The effect results in a modulation of the laser emission intensity as well as in a turn of the emission polarization by the sound strain. Theoretical treatment of the experimental data is presented.     

On cycles for the doubling map which are disjoint from an interval

Let \(T:[0,1]\rightarrow [0,1]\) be the doubling map and let \(0 . We say that an integer \(n\ge 3\) is bad for \((a,b)\) if all \(n\) -cycles for \(T\) intersect \((a,b)\) . Let \(B(a,b)\) denote the set of all \(n\) which are bad for \((a,b)\) . In this paper we completely describe the sets: $$\begin{aligned} D_2=\{(a,b) : B(a,b)\,\text {is finite}\} \end{aligned}$$ and $$\begin{aligned} D_3=\{(a,b) : B(a,b)=\varnothing \}. \end{aligned}$$ In particular, we show that if \(b-a<\frac{1}{6}\) , then \((a,b)\in D_2\) , and if \(b-a\le \frac{2}{15}\) , then \((a,b)\in D_3\) , both constants being sharp.     

О,О‐Dialkyl‐S‐(1,1‐dimethyl‐2‐oxoethyl)dithiophosphates: Synthesis and Reactions with n‐Nucleophiles

Hydrolysis of the new types of iminium salts was used to synthesize О,О‐dialkyl‐S‐(1,1‐dimethyl‐2‐oxoethyl)dithiophosphates or 2‐dialkoxythiophosphorylthio‐substituted aldehydes with carbon isochain. Reactions of aldehydes with N‐, N,N‐, and O,N‐nucleophiles gave new phosphorylated imines containing an acetal group at different positions, perhydro‐1,3‐diazol and oxazol with the diisopropoxythiophosphorylthio group in a side chain, and hydrazone of this aldehyde and diphenylphosphinylacetic acid hydrazide.     

Minimal spaser threshold within electrodynamic framework: Shape,size and modes

It is known (yet often ignored) from quantum mechanical or energetic considerations, that the threshold gain of the quasi‐static spaser depends only on the dielectric functions of the metal and the gain material. Here, we derive this result from the purely classical electromagnetic scattering framework. This is of great importance, because electrodynamic modelling is far simpler than quantum mechanical one. The influence of the material dispersion and spaser geometry are clearly separated; the latter influences the threshold gain only indirectly, defining the resonant wavelength. We show that the threshold gain has a minimum as a function of wavelength. A variation of nanoparticle shape, composition, or spasing mode may shift the plasmonic resonance to this optimal wavelength, but it cannot overcome the material‐imposed minimal gain. Furthermore, retardation is included straightforwardly into our framework; and the global spectral gain minimum persists beyond the quasi‐static limit. We illustrate this with two examples of widely used geometries: Silver spheroids and spherical shells embedded in and filled with gain materials.     

Chemometrics assisted spectrophotometric determination of pyridine in water and wastewater

The paper reports a direct method for the determination of pyridine in water and wastewater samples based on ultraviolet spectrophotometric measurements using multi-way modeling techniques. Parallel factor analysis (PARAFAC) and multi-way partial least squares (N-PLS) regression methods were employed for the decomposition of spectra and quantification of pyridine. The study was carried out in the pH range of 1.0-12.0 and concentration range of 0.67-51.7 μg mL⁻¹ of pyridine. Both the three-way PARAFAC and tri-PLS1 models successfully predicted the concentration of pyridine in synthetic (spiked) river water and field wastewater samples. The mean recovery obtained from PARAFAC regression model were 97.39% for the spiked and 99.84% for the field wastewater samples, respectively. The sensitivity and precision of the method for pyridine determination were 0.58% and 5.95%, respectively. The N-PLS regression model yielded mean recoveries of 99.29% and 100.18% for the spiked and field wastewater samples, respectively. The prediction accuracy of the methods was evaluated through the root mean square error of prediction (RMSEP). For PARAFAC, it was 0.65 and 0.82 μg mL⁻¹ for spiked river water and field wastewater samples, respectively, while for N-PLS, it was 0.25 and 0.37 μg mL⁻¹, respectively. Both the PARAFAC and N-PLS methods, thus, yielded satisfactory results for the prediction of pyridine concentration in water and wastewater samples.     

Fused 1,2-Diboraoxazoles Based on closo-Decaborate Anion–Novel Members of Diboroheterocycle Class

The novel members of the 1,2-diboraoxazoles family have been obtained. In the present work, we have carried out the intramolecular ring-closure reaction of borylated iminols of general type [B₁₀H₉N=C(OH)R]⁻ (R = Me, Et, ⁿPr, ⁱPr, ^tBu, Ph, 4-Cl-Ph). This process is conducted in mild conditions with 83–87% yields. The solid-state structures of two salts of 1,2-diboraoxazoles were additionally investigated by X-ray crystallography. In addition, the phenomena of bonding interactions in the 1,2-diboraoxazole cycles have been theoretically studied by the Quantum Theory of Atoms in Molecules analysis. Several local and integral topological properties of the electron density involved in these interactions have been computed.     

Progress in the chemistry of functional aramids properties

High-performance polymers based on amide aromatic rings are known as wholly aromatic polyamides or aramids. The arrangement and admirable properties of aramids are built on the basis of amide linkage and rigid aromaticity. Aramids are attractive because of their extraordinary bond strengths and very high stiffness. Synthetic aromatic polymeric chains provide increased mechanical resistance and thermal softening compared to aliphatic aramids. In addition, aramids exhibit high thermal stability, low creep, and good optical activity with fluorescence. Hence, aramids are found in advanced arenas for engineering thermoplastics such as transport applications, electroactive materials, films, bullet-proof body armor, smart materials, protective clothing, fibers, in nanocomposites as asbestos alternatives, cutting edge complexes in arming, high-temperature lining material, in space engineering, and more. The objective of this review is to make the field of aramids functionality more accessible to the materials science community, that is, scientists, academicians, and engineers.     

Planar piecewise linear random motions with jumps

In this paper, we study persistent piecewise linear multidimensional random motions. Their velocities, switching at Poisson times, are uniformly distributed on a sphere. The changes of direction are accompanied with subsequent jumps of random length and of uniformly distributed orientation. In this paper, we obtain some useful properties and formulae of distributions of these processes. In particular, we get these distributions in the cases of jumps with Gaussian and exponential distributions of jump magnitudes.