Abstract This work is an effort for determination of excited and ground state values dipole moments also quantum chemical computation two biologically active heterocyclic class compounds namely 3-[2-Oxo-2-(2-oxo-2H-chromen-3-yl)-ethylidene]-1,3-dihydro-indol-2-one (3OCE) 3-[2-Oxo-2-(3-oxo-3H-benzo[f]chromen-2-yl)-ethylidene]-1,3-dihydro-indol-2-one (3OBC). Redshift displayed by both the with so...

Optimal geometries, charge distributions, bond analysis, changes of Gibbs free energy, entropies and enthalpies of hydration, and hydrolysis reactions for mononuclear species of Zn(2+) including hydrated and hydrolysis complexes were investigated using quantum chemical calculations in the gas phase. Optimized geometrical structures showed that the stable hydrated and hydrolysis zinc species wit...

A theoretical DFT study was employed to investigate the different aspects of electronic structure of the salt of 1,1/(ethane-1,2-diyl)dipyridiniumbisiodate. The interactions between different molecular orbitals were considered by using DFT method. The results from the quantum mechanical calculations were then used to determine the role of donoracceptor interactions on the oxidation strength of ...

in the present work, the quantum theoretical calculations of the molecular structure of the 1-(1, 3-benzothiazol-2-yl)-3-(thiophene-5-carbonyl) thiourea has been predicted and are evaluated using density functional theory (dft) in gas phase. the geometry of the title compound was optimized by b3lyp/6-311+g and b3lyp/6-311+g* methods and the experimental geometrical parameters of the title compo...

The optimized structures of studied compounds 23-28 are non planner with the two phenyl at C3 and C9 are out of the molecular plane of thiazolo[3,2-a]pyridine as indicated from a dihedral angles of 710 and 1160 respectively, using DFT-B3LYP method with 6-311G(d,p) as basis set. The natural bonding orbital (NBO) analysis of the parent molecule 23 have been analyzed in terms of the hybridization ...

Beta-turns play an important role in peptide and protein chemistry, biophysics, and bioinformatics. The aim of this research was to study short linear peptides that have a high propensity to form beta-turn structures in solution. In particular, we examined conformational ensembles of beta-turn forming peptides with a general sequence CBz-L-Ala-L-Xaa-Gly-L-Ala-OtBu. These tetrapeptides, APGA, A(...

The 6-311G(d,p) and SDD basis sets have been used to calculate the vibration frequencies, DFT/B3LYP approach was optimize structure. energy gap of molecule has calculated using lowest unoccupied molecular orbital (LUMO) with highest occupied (HOMO). stability charge delocalization Title investigated natural bond (NBO) analysis. dipole moment, polarizability, first-order hyperpolarizability, as ...

The effect of interactions of various Ia and IIa cations with two positions of the adenine-thymine (A-T) and guanine-cytosine (G-C) base pairs on the geometries and individual hydrogen bond (HB) energies have been investigated by using the atoms in molecules (AIM) method at the B3LYP/6-311++G(d,p) level of theory. The cations that possess higher charge/radius (q/rad) ratio make higher changes o...

Lincosamides are a class of antibiotics used both in clinical and veterinary practice for a wide range of pathogens. This group of drugs inhibits the activity of the bacterial ribosome by binding to the 23S RNA of the large ribosomal subunit and blocking protein synthesis. Currently, three X-ray structures of the ribosome in complex with clindamycin are available in the Protein Data Bank, which...

A theoretical study on the multi-channel hydrogen addition of maleimide containing 2-hydroxy-benzophenone onto polyethylene in ultra-violet (UV) radiation cross-linking process was carried out using density functional theory (DFT) method at B3LYP/6–311 + G(d,p) level. The energetic information and minimum energy path (MEP) are calculated for nine reaction channels. electrophilic reactions two p...