DFT calculations, structural analysis, solvent effects, and non-covalent interaction study on the para-aminosalicylic acid complex as a tuberculosis drug: AIM, NBO, and NMR analyses.

In this study, the effect of non-covalent interactions on the para-aminosalicylic acid complex is explored using density functional theory (DFT) in the gas phase and the solution. Our findings exhibit that the achieved binding energies considerably change on going from the gas phase to the solution. Based on the obtained results, the absolute value of the binding energy of the complex in the polar solvents is lower than the non-polar ones while in the gas phase it is higher than the solution.

Methods for Direct Reductive N-Methylation of Nitro Compounds.

Direct reductive N-methylation of inexpensive and readily available nitro compounds as raw material feedstocks is more attractive and straightforward compared with conventional N-methylation of amines to prepare biologically and pharmaceutically important N-methylated amine derivatives. This strategy for synthesis of N-methylamines avoids prepreparation of NH-free amines and therefore significantly shortens the separation and purification steps. In recent years, numerous methylating agents and catalytic systems have been reported for this appealing transformation.

The recent development of donepezil structure-based hybrids as potential multifunctional anti-Alzheimer's agents: highlights from 2010 to 2020.

Dementia is a term used to define different brain disorders that affect memory, thinking, behavior, and emotion. Alzheimer's disease (AD) is the second cause of dementia that is generated by the death of cholinergic neurons (especially acetylcholine (ACh)), which have a vital role in cognition. Acetylcholinesterase inhibitors (AChEI) affect acetylcholine levels in the brain and are broadly used to treat Alzheimer's.

Alkoxysulfenylation of alkenes: development and recent advances.

Among the wide variety of synthetic transformations of inexpensive and abundant feedstock alkenes, vicinal difunctionalization of carbon-carbon double bonds represent one of the most powerful and effective strategies for the introduction of two distinct functional groups into target compounds in a one-pot process. In this context, the direct alkoxysulfenylation of alkenes has emerged as an elegant method to construct valuable β-alkoxy sulfides in an atom- and pot-economic manner utilizing readily accessible starting materials. Here, we review the available literature on this appealing research topic by hoping that it will be beneficial for eliciting further research and thinking in this domain.

Direct synthesis of sulfenamides, sulfinamides, and sulfonamides from thiols and amines.

Needless to say that organosulfur compounds with sulfur-nitrogen bonds have found various applications in diverse fields such as pharmaceuticals, agrochemicals, polymers, and so forth. Three major groups of such compounds are sulfenamides, sulfinamides, and sulfonamides which have been widely applied as building blocks in medical chemistry. Owing to their significant role in drug design and discovery programs, the search for and development of efficient, environmentally friendly, and economic processes for the preparation of the title compounds is of great importance in the pharmaceutical industry.

Recent trends in dehydroxylative trifluoro-methylation, -methoxylation, -methylthiolation, and -methylselenylation of alcohols.

Owing to the prevalence of hydroxyl groups on molecules, much attention has been paid to the synthesis of functionalized organic compounds by dehydroxylative functionalization of parent alcohols. In this context, dehydroxylative trifluoromethylation, trifluoromethoxylation, trifluoromethylthiolation, and trifluoromethylselenylation of readily available alcohols have recently emerged as intriguing protocols for the single-step construction of diverse structures bearing C-CF, C-OCF, C-SCF, and C-SeCF bonds, respectively. This Mini-Review aims to summarize the major progress and advances in this appealing research area with special emphasis on the mechanistic features of the reaction pathways.

Progress and recent trends in the direct selenocyanation of (hetero)aromatic C-H bonds.

This review covers recent advances in the direct selenocyanation of (hetero)aromatic C-H bonds with an emphasis on the reaction mechanisms. This novel approach is an effective means of preparing a variety of aromatic and heteroaromatic selenocyanates, which are extremely versatile synthetic precursors of selenium-containing compounds, such as selenols, seleninic acids, selenides, diselenides, and trifluoromethyl selenides.

Hydroxysulfonylation of alkenes: an update.

The direct difunctionalization of inexpensive and widely available alkenes has been recognized as a strong and straightforward tool for the rapid fabrication of complex molecules and pharmaceutical targets by introducing two different functional groups on adjacent carbon atoms of common alkene moieties in a single operation. This synthetic strategy avoids the purification and isolation of the intermediates and thus makes synthetic schemes shorter, simpler and cleaner. In this family of reactions, the hydroxysulfonylation of alkenes has emerged as an increasingly promising strategy for the synthesis of β-hydroxysulfones, which are found in many biologically important molecules and widespread applications in organic synthesis.

Density functional theory studies on C with substitutional TiN impurities.

In this paper, we have performed systematic theoretical surveys of C and its CTiN nanocages with n = 1-8 at DFT. Full optimization indicates none of the structures collapse to open deformed as segregated heterofullerene. Also, in order to avoid the resulted strain of fused five-pentagon configuration, some of them deform their cage at the Ti-N bonds and appear cubic-like.

Selective adsorption and dissociation of NO, NO, and NO molecules on Si-doped haeckelite boron nitride nanotube: an investigation for sensitive molecular sensors and catalysts.

The current study describes the investigation of the adsorption NO, NO, and NO on haeckelite boron nitride nanotube doped with Si (Si-doped haeck-BNNT) by means of density functional theory calculation (DFT). The obtained results confirmed the energetic stability of the optimized geometries and revealed that the adsorption of the gas molecules with the nanotube sidewall is a spontaneous process. The calculated work function of Si-doped haeck-BNNT in the presence of gas molecules is greater than that of a bare Si-doped haeck-BNNT sheet.

Substitution effects via aromaticity, polarizability, APT, AIM, IR analysis, and hydrogen adsorption in CTi nanostructures: a DFT survey.

In this paper, the substitution effects of titanium heteroatom(s) on aromaticity, the average isotropic polarizability (< α >), the atomic polar tensor (APT) charge, the electrostatic potential (ESP) map, and the atoms in molecule (AIM) analysis along with infrared (IR) spectroscopy of C fullerene and its CTi derivatives (n = 1-5) are probed via density functional theory (DFT). The nucleus-independent chemical shifts (NICS) specify that substitution effect causes more aromaticity character of the optimized heterofullerenes than benzene molecule and higher APT charge distribution upon surfaces of them than pure cage. The highest negative and positive APT charge distribution on carbons of CTi and titanium substitutions of CTi implies that these sites can be attacked more readily by electrophilic and nucleophilic regents, respectively.

Quantum chemical studies of mercaptan gas detection with calcium oxide nanocluster.

The electronic sensitivity and adsorption behavior for mercaptan natural gas of a CaO nanocluster were studied via ab initio computations. To be more specific, to fully grasp the influence of mercaptan molecules on the chemical and electronic features of CaO nanocluster, some parameters, namely, charge transfer of natural bond orbital, molecular electrostatic potential, binding energies, and frontier molecular orbitals, are computed. The interaction between CHS molecule and calcium atoms of CaO nanocluster through the sulfur head is strong.

Investigation of fused remote N-heterocyclic silylenes (frNHSis), at DFT.

We compared and contrasted the ΔΕ, band gap (ΔΕ), aromaticity, charge distribution, and reactivity of singlet (s) and triplet (t) benzopyridine-4-ylidene as the fused remote N-heterocyclic carbene (frNHC) and frNHSis with different fused aromatic rings, at (U)B3LYP/AUG-cc-pVTZ and (U)M06-2X/AUG-cc-pVTZ levels of theory. In this investigation, we found (1) all s and t divalent states appear as minimum structures, for having no negative force constant. Nonetheless, only singlets present more thermodynamic stability than their triplet analogous; (2) the trend of ΔΕ in kcal/mol is ortho-pyrrole (52.

Characterization of titanium influences on structure and thermodynamic stability of novel CTi nanofullerenes (n=1-5): a density functional perspective.

In this survey, effects of titanium heteroatom(s) on structural parameters and thermodynamic stability of C fullerene and its CTi derivatives (n = 1-5) are compared and contrasted, at DFT levels of theory. The results show that in going from CTi to CTi, binding energy increases while absolute value heat of atomization decreases. According to vibrational frequency analysis, excepting CTi, the other optimized structures give no imaginary frequency as true minima.

Knockdown of Angiopoietin-like protein 4 suppresses the development of colorectal cancer.

Colorectal cancer, is the growth of cancer cells in the part of the colon. Angiopeptin is one of the growth factors in the human body that is particularly effective in the regulatory process. In this research, the regulatory role and its mechanism of Angiopoietin-like protein 4 (ANGPTL4) in colorectal cancer (CRC) metastasis, has been studied.

The application of DNA molecular markers in the study of Codonopsis species genetic variation, a review.

Codonopsis genus is comprised of species that are perennial plants primarily distributed across all east, southeast, and Central Asia. The most famous species of Codonopsis are C. tangshen, C.

Methods for direct C(sp)-H bonds azidation.

Direct functionalization of C-H bonds has attracted great attention in recent years from the perspectives of atom and step economy. In this context, a variety of processes have been developed for the construction of synthetically and biologically important organic azides through the oxidative C-H bonds azidation. In this review, we have summarized recent progress in the direct azidation of C(sp)-H bonds.

One-pot synthesis of 2-amino-4-chromene derivatives by MNPs@Cu as an effective and reusable magnetic nanocatalyst.

In this research, MNPs@Cu as an effective and recyclable nanocatalyst was prepared and characterized using different methods including Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). After the characterization of this new nanocatalyst, it was efficiently used for the promotion of the one-pot synthesis of 2-amino-4-chromene derivatives one-pot three-component reaction of the enolizable compound, malononitrile, and arylaldehydes under solvent-free conditions at 90 °C. The procedure gave the desired products in high-to-excellent yields in short reaction times.

Hydrogen and syngas production by catalytic gasification of algal biomass (Cladophora glomerata L.) using alkali and alkaline-earth metals compounds.

The steam gasification of algal biomass (Cladophora glomerata L.) in presence of alkali and alkaline-earth metal compounds catalysts was studied to enhance the yield of syngas and reduce its tar content through cracking and reforming of condensable fractions. The commercial catalysts used include NaOH, KHCO, NaPO and MgO.

Gasification of algal biomass (Cladophora glomerata L.) with CO/HO/O in a circulating fluidized bed.

Gasification is one of the most important thermochemical routes to produce both synthesis gas (syngas) and chars. The quality of produced syngas wieldy depends on the operating conditions (temperature, residence time, heating rate, and gasifying agent), hydrodynamic properties of gasifier (particle size, minimum fluidization velocity, and gasifier size), and type of feedstock (coal, biomass, oil, and municipal solid wastes). In the present study, simulation of syngas production via circulating fluidized bed (CFB) gasification of algal biomass (Cladophora glomerata L.