In this work, quantum chemical calculations were performed on valdecoxib (VLB), a highly selective and potent COX-2 inhibitor, its hydroxylated derivative (1H-VLB), an active metabolite. The geometry optimizations frequency carried out by using density functional theory (DFT)/B3LYP with the 6-311++G (d, p) basis set. To define water phase behaviors, renewed universal SMD solvation model for bot...

Density functional theory methods(DFT) and natural bond orbital (NBO) analysis were used to investigate the effects of isomerism and side chain mutation at a microscopic level on the stability, binding energy and NMR/NQR tensors of structural isomers, L- methionylasparagine (Met-Asn) and L- asparagylmethionine (Asn-Met) in the gas phase. The results represented that the isomerism and side chain...

A DFT-SOFM-RBFNN method is proposed to improve the accuracy of DFT calculations on Y-NO (Y = C, N, O, S) homolysis bond dissociation energies (BDE) by combining density functional theory (DFT) and artificial intelligence/machine learning methods, which consist of self-organizing feature mapping neural networks (SOFMNN) and radial basis function neural networks (RBFNN). A descriptor refinement s...

Abstract The article compares the experimental Fourier transform-infrared, Ultraviolet-visible (UV-vis), and proton nuclear magnetic resonance ( 1 H NMR) spectra of voriconazole fluconazole with density functional theory (DFT) calculations using five different functionals. results were compared previously reported data related to its analogue – posaconazole. analysis calculated infrared (IR) us...

UNLABELLED BACKGROUND Chalcones are ubiquitous natural compounds with a wide variety of reported biological activities, including antitumoral, antiviral and antimicrobial effects. Furthermore, chalcones are being studied for its potential use in organic electroluminescent devices; therefore the description of their spectroscopic properties is important to elucidate the structure of these mol...

The capabilities and limitations of the Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional are investigated as applied to studies of mixed-valent multinuclear oxomanganese complexes. Benchmark calculations involve the analysis of structural, electronic and magnetic properties of di-, tri- and tetra-nuclear Mn complexes, previously characterized both chemically and spectroscopically, includ...

the physical and chemical properties of pyrazole and pyrazoline molecules were theoreticallystudied by gaussian 03, software with nmr and molecular orbital calculations at b3lyp/6-31g andb3lyp/6-31+g(d) levels, in gas phase and solution. in this study a comparison effect of threesolvents with different dielectric constants on pyrazole and pyrazoline molecules in aspect energyinteraction between...

The optimized molecular structures, harmonic vibrational wavenumbers, and corresponding vibrational assignments of 2-, 3and 4-cyanopyridines have been calculated using Gaussian 03 set of quantum chemistry code. Calculations were carried out at Becke-3-Lee-Yang-Parr (B3LYP) density functional theory (DFT) level using the standard 6-311++G(d,p)basis set. The geometrical parameters, thermodynamic ...

Blue-emitting heteroleptic aluminum(III) bis(2-methyl-8-quinolinolate)phenolate complexes were synthesized. A tunable, blue-to-green emission is achieved by attaching electron-withdrawing modulators to the emisssive quinaldinate ligand. The electronic nature of modulator substituents attached to the position of the highest HOMO (highest occupied molecular orbital) density is used to modulate li...

The conformational landscape of phenylisoserine (PhIS) was studied. Trial structures were generated by allowing for all combinations of single-bond rotamers. Based on the B3LYP/aug-cc-pVDZ calculations 54 conformers were found to be stable in the gas phase. The six most stable conformers were further optimized at the B3LYP/aug-cc-pVTZ and MP2/aug-cc-pVDZ levels for which characteristic intramol...