1,824 Results Found

The present work introduced first-principles calculation to explore the substitution behavior of Ag atoms for Al or Ti atoms in the Ti₂AlC MAX phase ceramic. The effect of Ag substitution on supercell parameter, bonding characteristic, and stability...

Intermetallic alloys based on A15-type compounds, including cubic Ti₃Sb, attract increasing interest due to their tunable electronic properties and potential for surface-related functional applications. Here, the interaction of nitrogen with Ti₃Sb is...

The competition between base-induced elimination (E2) and bimolecular nucleophilic substitution (S_N2) is of significant importance in organic chemistry and is influenced by many factors. The electronic structure calculations for the gas-phase reactio...

The 4-aminoquinazoline scaffold is a privileged structure in medicinal chemistry. Regioselective nucleophilic aromatic substitution (S_NAr) for replacing the chlorine atom at the 4-position of 2,4-dichloroquinazoline precursors is well documented in t...

This study employs density functional theory (DFT) simulations to systematically investigate the structural and optoelectronic modifications induced by the substitution of metal ions (Mg²⁺, Ca²⁺, Mn²⁺, Fe²⁺/³⁺, Co²⁺, and Ni²⁺) in kaolinite. First-pri...

The chloride-chloride exchange reaction in arenesulfonyl chlorides was investigated experimentally and theoretically by density functional theory (DFT) calculations. The second order rate constants and activation parameters of this identity reaction...

This paper studies the shear strength of an anti-rust bolt with a spiral oil-guiding slot and oil-bearing hole by conducting a simulation and experiment. A finite element model with the bolt and the clamp tool is developed for simulating the shearing...

This research focuses on the X-ray structure of 4,6-dichloro-5-nitrobenzofuroxan 1 and of some of its amino derivatives (4a, 4e, 4g, and 4l) and on DFT calculations concerning the nucleophilic reactivity of 1. We have found that by changing the solve...

Boron-doped graphite was prepared by the heat treatment of coke using B₄C powder as a graphitization catalyst to investigate the effects of the substitutional boron atoms on the interlayer spacing of graphite. Boron atoms can be successfully incorpor...

The effect of isotopic substitution on near-infrared (NIR) spectra has not been studied in detail. With an exception of few major bands, it is difficult to follow the spectral changes due to complexity of NIR spectra. Recent progress in anharmonic qu...

In multiphase (≥3) equilibrium calculations, when the Newton method is used to solve the material balance (Rachford-Rice) equations, poorly conditioned Jacobian can lead to false convergence. We present a robust successive substitution method that so...

The influence of steric repulsion between the NMe₂ group and a second ortho-(peri-)substituent in the series of 1-dimethylaminonaphthalene and N,N-dimethylanilene ortho-oximes on the ease of the NMe₂ group’s intramolecular nucleophilic substitu...

The wavenumbers of the IR absorption bands of the C=O, S=O and N-H stretching vibrations for a series of p-substituted N-phenylsulfonylbenzamides were measured in trichloromethane. The bond orders, Mulliken charges, charge densities and heats of form...

Halogen bonds (XBs) between metal anions and halides have seldom been reported because metal anions are reactive for XB donors. The pyramidal-shaped Mn(CO)₅⁻ anion is a candidate metallic XB acceptor with a ligand-protected metal core that main...

Benzo[1,2-d:4,5-d′]bis([1,2,3]thiadiazole) (isoBBT) is a new electron-withdrawing building block that can be used to obtain potentially interesting compounds for the synthesis of OLEDs and organic solar cells components. The electronic structur...

Tonsil Actisil FF, a commercial bentonitic clay, promotes the formation of a series of electrophilic-aromatic-substitution products from para-methoxybenzyl acetate in carbon disulfide. The molecules obtained correspond to linear isomeric dimers, trim...

A series of xylene charge-transfer complexes with fluorine-substituted tetracyanoquinodimethane (TCNQ) acceptors were studied experimentally and theoretically in order to reveal the role of various intermolecular interactions on stoichiometry and the...

Uridine phosphorylases are used for biotechnological synthesis of pyrimidine derivatives and, moreover, their substrates and inhibitors are used in medicine. Therefore, studies of the mechanisms of the chemical reaction catalyzed by the enzyme and it...

1,6- and 1,7-regioisomers of diamino-substituted perylene tetracarboxylic dianhydrides (PTCDs) with different n-alkyl chain lengths (n = 6, 12 or 18) were synthesized and characterized by NMR spectroscopy and high-resolution mass spectrometry. These...

Elaboration of a convenient route towards donor-substituted pyrazoles from heteropropargyl precursors is challenging due to a number of thermodynamically favorable side reactions (e.g., acetylene–allene isomerization and Glaser homocoupling). I...

An analysis of the effects induced by F, Cl, and Br-substituents at the α-position of both, the hydroxyl or the amino group for a series of amino-alcohols, HOCH₂(CH₂)_nCH₂NH₂ (n = 0–5) on the strength and characteristics of their OH···N or NH···O intr...

A series of phosphorus and selenium peri-substituted acenaphthene species with the phosphino group oxidized by O, S, and Se has been isolated and fully characterized, including by single-crystal X-ray diffraction. The P(V) and Se(II) systems showed f...

To develop promising adsorbent candidates for adsorptive denitrogenation, we screened the adsorption of NO, NO₂, and NH₃ in 19 M-HKUST-1 (M = Be, Fe, Ni, Cr, Co, Cu, V, Zn, Mo, Mn, W, Sn, Ti, Cd, Mg, Sc, Ca, Sr, and Ba) systematically using first-pri...

4-(4-nitrophenyl)thiomorpholine, the title compound, has been used as a precursor for the corresponding 4-thiomorpholinoaniline, which is a useful building block in medicinal chemistry. The crystal and molecular structures of the title compound, howe...

This article presents a detailed comprehensive investigation of the ortho fluoro- and chloro- substituted benzoic acids both, as isolated molecules and in the crystalline phase. Quantum chemical calculations performed within the density functional th...

The gating mechanism of voltage sensitive ion channels is generally considered to be the motion of the S4 transmembrane segment of the voltage sensing domains (VSD). The primary supporting evidence came from R→C mutations on the S4 transmembrane segm...

Computational calculations have been used successfully to explain the reactivity of the >C=P- functionality in pyrido-annelated 1,3-azaphospholes. Theoretical investigation at the Density Functional Theory (DFT) level shows that the lone pair of t...

The mechanisms of three selected identity substitution reactions at phosphorus and sulfur occurring with stereospecific inversion have been investigated using density functional theory (DFT). The first identity reaction between methoxyl anion and met...

The analysis of the IR carbonyl bands of some 3-(4′-substituted phenylsulfanyl)-1-methyl-2-piperidones 1–6 bearing substituents: NO₂ (compound 1), Br (compound 2), Cl (compound 3), H (compound 4) Me (compound 5) and OMe (compound 6) supported by B3LY...

Calculations of nuclear magnetic resonance (NMR) isotopic shifts often rest on the unverified assumption that the “vibration hole”, that is, the change of the vibration motif upon an isotopic substitution, is strongly localized around the...

In this study, the first-principles method is adapted to establish key data for β-Mo₂C with various point defects. A particular focus is comparatively studying the effects of point vacancies and different substitutional doping elements on the st...

To gain insight into the effect of Si/C arrangement on the molecular framework of strained polyhedral compounds, dodecahedrane analogues containing equal numbers of carbon and silicon (Si/C equally mixed dodecahedrane analogues) were investigated usi...

Monovalent NHC-nickel complexes bearing triarylphosphine, in which fluorine is incorporated onto the aryl groups, have been synthesized. Tris(3,5-di(trifluoromethyl)-phenyl)phosphine efficiently gave a monovalent nickel bromide complex, whose structu...

Two new 2-N-phenylamino-(4 or 6)-methyl-3-nitropyridine derivatives were synthesized. Their structures were characterized on the basis of X-ray diffraction, IR, and Raman spectra as well as electron UV-Vis and emission spectra measurements. The exper...

The diastereotopy of the methylene protons at positions 2 and 6 in 1,4-dihydropiridine derivatives with various substituents has been investigated. NMR spectroscopy and quantum chemistry calculations show that the CH···O intramolecular hydrogen bond...

In this study, the degradation mechanism of chloroacetanilide herbicides in the presence of four different nucleophiles, namely: Br⁻, I⁻, HS⁻, and S₂O₃⁻², was theoretically evaluated using the dispersion-corrected hybrid functional wB97XD and the DGD...

A simple, fast and cost-effective three-step synthesis of 1-methyl-8-phenyl-1,3-diazaspiro[4.5]decane-2,4-dione has been developed. The reactions described herein proceed readily, with high yields and no further purification. Therefore, the proposed...

We provide a nonlinear model of intersectoral balance with constant elasticity of substitution (CES) production functions of industries and CES utility function of final consumer for the study of intersectoral linkages in the Kazakhstan economy. The...

The activity of natural phenols is primarily associated to their antioxidant potential, but is ultimately expressed in a variety of biological effects. Molecular scaffold manipulation of this large variety of compounds is a currently pursued approach...

In this manuscript, the synthesis and single crystal X-ray diffraction characterization of four N-substituted 1,3,5-triazinanes are reported along with a detailed analysis of the noncovalent interactions observed in the solid state architecture to th...

Crude ethyl acetate extract of Gerbera piloselloides (L.) Cass. was investigated by dual high-resolution PTP1B/α-glucosidase inhibition profiling and LC-PDA-HRMS. This indicated the presence of a series of unprecedented prenyl- and geranyl-subs...

The supramolecular structure of the crystal products–N-[2-chloro-2-(silatranyl)ethyl]-4-nitro-benzenesulfonamide 4d and N-chloro-N-[2-chloro-1-(silatran-1-yl-methyl)ethyl]benzene-sulfonamide 5a was established by X-ray diffraction analysis data...

In this paper, azulenes substituted with thiophen– or furan–vinyl–pyridine are reported as heavy metal ligands in systems based on chemically modified electrodes. We undertook a computational study of their structures using density...

Electrical energy substitution is an important way to achieve the optimization of the energy consumption structure as well as to alleviate environmental problems, and it is also an important source of benefits of the integrated energy system. However...

In the present work, we performed calculations of the kinetic isotope effect (KIE) on H/D, ¹⁴N/¹⁵N, ¹⁶O/¹⁸O, and ¹²C/¹³C isotopic substitution in the dissociation of beta-sheet polyglycine dimers of different lengths into two monomer chains. This dis...

The structural changes occurring in tialite due to the formation of magnesium-titanate–aluminum-titanate solid solutions were determined. For this purpose, a DFT simulation of the structural changes was performed. The simulation proposed a numb...

The site preference for each cation and site in beryl based on bond-length calculations was determined and compared with analytical data. Tetrahedral SiO₄ six-membered rings normally have no substitutions which results from very compact Si⁴⁺–O...

The effort of numerical heat transfer calculations increases with the complexity and size of the domains and surfaces under consideration. When calculating heat transfers on finned arrays, one way to reduce this effort is to substitute the fins. Ther...

The structural, electronic, and optical properties of pure and Ce-doped BaTiO₃ were investigated based on first-principle calculation. Here, we concentrate on understanding the effect of the substitution of Ce for Ba and Ti sites in the equilibrium l...

The intriguing ability of C-phenyl-nitrilimine to co-exist as allenic and propargylic bond-shift isomers motivated us to investigate how substituents in the phenyl ring influence this behavior. Building on our previous work on the meta- and para-OH s...