Comparative Structural Study of Three Tetrahalophthalic Anhydrides: Recognition of X···O(anhydride) Halogen Bond and πh···O(anhydride) Interaction

Structures of three tetrahalophthalic anhydrides (TXPA: halogen = Cl (TCPA), Br (TBPA), I (TIPA)) were studied by X-ray diffraction, and several types of halogen bonds (HaB) and lone pair···π-hole (lp···πh) contacts were revealed in their structures. HaBs involving the central oxygen atom of anhydride group (further X···O(anhydride) were recognized in the structures of TCPA and TBPA. In contrast, for the O(anhydride) atom of TIPA, only interactions with the π system (π-hole) of the anhydride ring (further lp(O)···πh) were observed. Computational studies by a number of theoretical methods (molecular electrostatic potentials, the quantum theory of atoms in molecules, the independent gradient model, natural bond orbital analyses, the electron density difference, and symmetry-adapted perturbation theory) demonstrated that the X···O(anhydride) contacts in TCPA and TBPA and lp(O)···πh in TIPA are caused by the packing effect. The supramolecular architecture of isostructural TCPA and TBPA was mainly affected by X···O(acyl) and X···X HaBs, and, for TIPA, the main contribution provided I···I HaBs.

Synthesis, Molecular Characterization, Biological and Computational Studies of New Molecule Contain 1,2,4-Triazole, and Coumarin Bearing 6,8-Dimethyl

Synthesis 4-(((4-ethyl-5-(thiophen-2-yl)-4H-1,2,4-triazol-3-yl)thio)methyl)-6,8-dimethyl-coumarin and spectral analysis is carried out using the FT-IR and NMR with the help of quantum chemical calculation by DFT/6-311(d,p). The molecular electrostatic potentials and frontier molecular orbitals of the title compound were carried out at the B3LYP/6-311G(d,p) level of theory. Antimicrobial, antioxidant activity, and In vitro cytotoxic for cell lines were observed. The result shows that the theoretical vibrational frequencies, 1H-NMR and 13C-NMR chemical shift, agree with experimental data. In vitro studies showed that antimicrobial activity was weak, particularly against bacteria such as E. coli, S. aureus, P. aeruginosa, and B. cereus. The test compound's oxidative stress index (OSI) has appeared as 0.079 ± 0.214 in antioxidant and oxidant capacity studies. The compound did not cause a harmful cytotoxic effect on healthy cell lines and showed no potential for anticancer activity on cancerous cell lines such as MCF-7 and MKN-45.

Intermolecular binding preferences of haloethynyl halogen-bond donors as a function of molecular electrostatic potentials in a family of N-(pyridin-2-yl)amides

The roles played by halogen bonds and hydrogen bonds in the crystal structures of N-(pyridin-2-yl)amides were evaluated and rationalised in the context of calculated molecular electrostatic potentials.

Computational Notes on The Effect of (Li-Na-K) on Calcium Zinc Phosphate Oxide Glasses

A model molecule for P4O10-ZnO-CaO is constructed to build Calcium Zinc Phosphate Oxide glasses. Then the effect of alkalis Li; Na and K upon the model molecule is studied with ab initio Hartree-Fockat HF/3-21G** level of theory. The overall aim is to evaluate the electronic properties of both the model molecules and alkali substituted molecules. The calculated parameters, including highest occupied molecular orbital/lowest unoccupied molecular orbital (HOMO/LUMO) bandgap energies; Total dipole moment (TDM) and molecular electrostatic potentials (MESP) are calculated. It has also been observed that the calculated TDM of the glassy system P4O10-ZnO-CaO is increased while the HOMOH/LUMO band gap is decreased as an indication for the reactivity of the studied model molecules. The active sites for the studied models are described by the calculated MESP, which is confirming the results of both TDM and HOMO/LUMO.

Complexes Between Adamantane Analogues B4X6 -X = {CH2, NH, O ; SiH2, PH, S} - and Dihydrogen, B4X6:nH2 (n = 1–4)

In this work, we study the interactions between adamantane-like structures B4X6 with X = {CH2, NH, O ; SiH2, PH, S} and dihydrogen molecules above the Boron atom, with ab initio methods based on perturbation theory (MP2/aug-cc-pVDZ). Molecular electrostatic potentials (MESP) for optimized B4X6 systems, optimized geometries, and binding energies are reported for all B4X6:nH2 (n = 1–4) complexes. All B4X6:nH2 (n = 1–4) complexes show attractive patterns, with B4O6:nH2 systems showing remarkable behavior with larger binding energies and smaller B···H2 distances as compared to the other structures with different X.

Electron densities of two cyclononapeptides from invariom application

The nonapeptides cyclo(Val-Leu-Pro-Ile-Leu-Leu-Leu-Val-Leu) (I) and cyclo(Val-Leu-Pro-Ala-Leu-Leu-Leu-Val-Leu) (II) were identified as promising candidates for the development as potential anti-cancer drugs. We report a re-refinement of deposited single-crystal X-ray diffraction data with aspherical scattering factors from the invariom database. A subsequent evaluation of the molecular electron density distribution and of the differences in their molecular electrostatic potentials provides insight in their activities. The sequences differ only in residue 4, Ile in (I) and Ala in (II). Since the anti-tumor potency is reduced for the Ala peptide (II), the causes for the differences seen in activity between (I) and (II) were examined from a structural and from an electron density (ED) point of view. The exchange at residue 4 does not lead to significant changes in molecular geometry. Molecular Hirshfeld surfaces and electrostatic potential (ESP) isosurfaces show accumulations of intermolecular interactions in regions adjacent to the Ile/Ala residues indicating preferred interactions with a potential receptor in these regions. The concentrations of intermolecular interactions were localized on the Hirshfeld surfaces through an extended basin of ED concentration close to the Ile/Ala residues. Differences in the electrostatic potentials (ESPs) between (I) and (II) were only found at the Ile/Ala site and were very close to zero otherwise.

Geometrical, vibrational and physical properties of polyvinyl chloride nanocomposites: Molecular modeling approach

B3LYP/6-31G([Formula: see text], [Formula: see text]) quantum mechanical calculations were conducted to study polyvinyl chloride (PVC) and PVC with metal oxides (ZnO and CuO). Accordingly, model molecules for PVC; PVC/[Formula: see text]ZnO; PVC/[Formula: see text]CuO and PVC/[Formula: see text]ZnO/[Formula: see text]CuO, where [Formula: see text] and [Formula: see text], 2 and 3, were proposed. The calculated results of total dipole moment (TDM), HOMO–LUMO energy band gap, and molecular electrostatic potentials (ESPs) indicated that the conductivity of PVC is increased and its surface became more reactive due to interaction with metal oxides. The effect of hydration on PVC was also studied at the same level of theory in order to assess the effect of up to 23 water molecules on PVC. The TDM value of PVC is increased but HOMO/LUMO band gap energy value is decreased because of hydration. Moreover, the results of calculated ESP indicated that the reactivity in the presence of water molecules increased, which could indicate possible degradation of PVC. Additionally, some geometrical parameters were studied. Furthermore, the scaled infrared spectrum (IR) for PVC was also calculated at B3LYP/6-31G ([Formula: see text], [Formula: see text]) and indicated that there are two bands at 2990[Formula: see text]cm[Formula: see text] and 2975[Formula: see text]cm[Formula: see text] in comparison with Fourier transform infrared spectrum (FTIR).