in this research at the first, captopril drug (ca) and its fullerene connected form (fca) wereoptimized. natural bond orbital (nbo) calculations for these compounds were carried out at theb3lyp/6-31g quantum chemistry level, in the gas phase and the liquid phase. these calculations canbe performed at different accuracy levels depending on the aim of the theoretical study [1]. forinstance, densi...

Density function M06 method has been used to optimize the geometries of shikonin -thymine at 6-311++G** basis. Finally, fourteen stabilized complexes have been obtained. Theories of atoms in molecules (AIM) and natural bond orbital (NBO) have been utilized to investigate the hydrogen bonds involved in all the systems. The interaction energies of all the complexes were corrected by basis set sup...

Fourier transform Raman and infrared spectra of 4-hydroxy-2,6-dimethyl pyrimidine (HDMP) were recorded and interpreted by comparison with respective theoretical spectra calculated using HF and B3LYP methods. The HDMP equilibrium geometry with Cs symmetry, harmonic vibrational frequencies, infrared and Raman intensities were determined using HF/6-311G and B3LYP/6-311G level of theories. The band...

A theoretical study of the peri interactions, both intramolecular hydrogen (HB) and chalcogen bonds (YB), in 1-hydroxy-8YH-naphthalene, 1,4-dihydroxy-5,8-di-YH-naphthalene, and 1,5-dihydroxy-4,8-di-YH-naphthalene, with Y = O, S, and Se was carried out. The systems with a OH:Y hydrogen bond are the most stable ones followed by those with a chalcogen O:Y interaction, those with a YH:O hydrogen bo...

We report the synthesis of penicillamine-protected Ag20 nanoclusters (NCs), with properties of high monodispersity, red fluorescence and water solubility. Full characterization of the Ag20 NCs is addressed, along with first-principles optimization calculations, revealing the chemical composition and structure of the as-prepared Ag NCs within a molecular formula [Ag20(DPA)18-H]-. Moreover, natur...

Mercaptopurine is a medicine used to prevent the formation and spread of cancer cells. Mercaptopurine, known chemically as 1,7-dihydro-6H-purine-6-thione, is an analogue of the purine bases adenine and hypoxanthine. This work reports an investigation of anticancer drug Mercaptopurine with the combined density functional theory and Its structure were optimized at B3LYP/6-31G*, level and The mole...

In this study interaction of phenothiazine sulfur dye with (5, 5) armchair open-end boron nitride nanotubes (BNNTs) in interaction (with a length of 7 Å) was investigated. The impacts of the estereoelectronic effect associated with donor-acceptor electron delocalizations, dipole-dipole interactions and total steric exchange energies on the structural and electronic properties and reactivity of ...

Centrosymmetric species with AB2 boding motif where central atom (A) is relatively more electronegative than the end ligands (B atoms) have been predicted to exhibit an unusual form of three-center/four-electron (3c/4e) long-bonding bonding/antibonding interactions occur between two (B–B) bypassing albeit via sharing latter’s lone pair. Such a long-bond sigma- and pi-type has so far as single b...

EPR hyperfine coupling constants of dinitrobenzoic acid anion radicals were calculated by using (DFT) with the use B3LYP functional at LanL2DZ, LanL2MB, EPR-II, EPR-III, 6-31+G(d) and 6-31++ G(d,p) basis sets. It was found that LanL2DZ is best set from correlation graphs between theoretical experimental results. Thus, in this set, structures formed spectra distributions spin density all determi...

In this study, electronic structures of ground state of pure vanadium sub-nano clusters, Vn (n=2-5), and their interactions with small ligands for example CO and triplet O2 molecules are investigated by using density functional theory (DFT) calibration at the mPWPW91/QZVP level of theory. The favorable orientations of these ligands in interaction with pure vanadium sub-nano clusters were determ...