Synthesis, quantum-chemical calculations and virtual screening of the alkaloid cytisine derivatives

The synthesis of some cytisine derivatives was carried out in the work. The article provides the data of quantum-chemical calculation and virtual screening of the alkaloid cytisine derivatives synthesized. At the same time, the reaction centers of the cytisine derivatives molecules were determined. In order to study the reactivity of the derivatives obtained (namely cinnamoylcytisine, lipoylcytisine, and cytisinylisoalantholactone) the quantum-chemical calculations were conducted to determine the energy and charge characteristics of the molecules. The results indicate a sufficient thermodynamic stability of the cinnamoylcytisine and lipoylcytisine molecules. The cytisinylisoalantholactone molecule is not stable according to the results of quantum chemical calculations. The data on the energy values of the frontier molecular orbitals show that, in general, all molecules exhibit electrophilic properties. A bioprediction was implemented using PASS (Prediction of Activity Spectra for Substances) as one of the most efficient and well-known computer program with the aim of detailed study and the probable establishment of the biological activity of the synthesized cytisine derivatives. Based on the results of virtual screening, promising types of alkaloid cytisine derivatives were identified, which are potential sources of original drugs

Evolution of Physicochemical Properties of 2-(2-(4-(4-chloro) phenyl) vinyl)-1, 1, 3-trimethyl-1H-benzo[e] Indolium Iodide via Experimental and Quantum Chemical Calculation for Third-Harmonic Generation Applications

In this work, the authors have reported the synthesis, crystal structure, and physicochemical properties of new Indolium based nonlinear optical crystal of 2-(2-(4-(4-chloro) phenyl) vinyl)-1, 1, 3-trimethyl-1H-benzo[e] Indolium iodide. The title crystal was grown by slow evaporation technique using methanol as a solvent. The harvested crystal is subjected to the single-crystal X-ray diffraction study and found that the title crystal belongs to the monoclinic system with a space group of P21/n. The bandgap and optical window of the material are studied by UV-visible spectroscopic analysis, and the found values are 4.2 eV and 295-800 nm, respectively. The grown crystal is subjected to analyze the thermal stability and found that high-temperature stability value upto 264 oC and which is sufficient for industrial applications. Furthermore, the effect of temperature on the grown crystal dielectric properties such as dielectric constant and dielectric losses is investigated by impedance spectroscopic analysis. The molecular charge transfer on the material is studied from density functional theory. The various intermolecular interactions existence in the crystal is explored from Hirshfeld surface analysis. Finally, the Z-scan parameters expose that title crystal is a potential material for third-harmonic generation applications. The overall structural studies and functional properties disclose that the grown crystal is well suitable for harmonic generation applications.

Semiempirical Quantum Chemical and Ab Intio Study of Co(Ii), Ni(Ii),Cu(Ii) and Zn(Ii) Complexes with the Azo Dye Derived from 4-Amino Antipyrine and 2,4-Dihydroxy Acetopheone

Semi-empirical quantum chemical calculation was made to study the nucleophilicity of the ligand and to study the mode of bonding between the ligand and the metal ions. The natural atomic charge at different atomic sites of the ligand has been calculated along with the electrostatic potential map to predict the reactive sites for electrophilic and nucleophilic attack. The theoretical spectral data such as IR, NMR and electronic have been calculated and compared with the experimentally generated data.

Visualization of magnesium and rubidium ion hydration in sulfocationite using quantum chemical calculation

Based on the data of ab initio calculation of the structure of (RSO3)2Mg (H2O)18 and (RSO3Rb)2(H2O)16 clusters, which simulate the structure of swollen sulfostyrene ion exchangers in the corresponding ionic forms and a water cluster of comparable size, the numbers of water molecules directly bound to cations and their coordination numbers, including the oxygen atoms of the sulfonic groups linked to the cation, were calculated. It is shown that the first molecular layer around the magnesium ion is formed from water molecules with the highest binding energy with the cluster, and around the rubidium ion – from the molecules of the nearest environment with the lowest binding energies. This is explained by the fact that the transfer of water molecules from its volume to magnesium hydrate is energetically favorable, but not to rubidium hydrate. Therefore, the magnesium ion builds its hydrate mainly from water molecules with the highest binding energy in order to obtain the greatest energy gain, and the rubidium ion – from molecules with the lowest energy, which provides the smallest energy loss.

CALCULATION OF THE ELECTRONIC STRUCTURE OF SOME EPOXY MOLECULES BY THE DFT METHOD

In this work, we performed a quantum-chemical calculation of some epoxy molecules: 1,2-epoxy-butene, 1,2-epoxy-2-methylpropane, 1,2 epoxyethane by the density functional theory DFT. An optimized geometric and electronic structure of these compounds is obtained. It was found that the studied epoxides belong to the class of very weak СH-acids (pKa = 28-30).

Measurement report: The importance of biomass burning in light extinction and direct radiative effect of urban aerosol during the COVID-19 lockdown in China

To mitigate climate change in China, a better understanding of optical properties of aerosol is required due to the complexity in emission sources. Here, an intensive real-time measurement was conducted in an urban area of China before and during the lockdown of Coronavirus Disease 2019 (COVID-19), to explore the impacts of anthropogenic activities on aerosol light extinction and direct radiative effect (DRE). The mean light extinction coefficient (bext) reduced from 774.7 ± 298.1 Mm−1 during the normal period to 544.3 ± 179.4 Mm−1 during the lockdown period. The generalized addictive model analysis indicated that the large decline of bext (29.7 %) was entirely attributed to the sharp reductions in anthropogenic emissions. Chemical calculation of bext based on the ridge regression analysis showed that organic aerosol (OA) was the largest contributor to bext in both periods (45.1–61.4 %), and contributions of two oxygenated OAs to bext increased by 3.0–14.6 % during the lockdown. A hybrid environmental receptor model combining with chemical and optical variables identified six sources of bext. It was found that bext from traffic-related emission, coal combustion, fugitive dust, nitrate plus secondary OA (SOA) source, and sulfate plus SOA source decreased by 21.4–97.9 % in the lockdown, whereas bext from biomass burning increased by 27.1 % mainly driven by undiminished needs of residential cooking and heating. The atmospheric radiative transfer model was further used to illustrate that biomass burning instead of traffic-related emission became the largest positive effect (10.0 ± 10.9 W m−2) on aerosol DRE in the atmosphere during the lockdown. Our study provides insights into aerosol bext and DRE from anthropogenic sources, and the results implied the importance of biomass burning for tackling climate change in China in the future.