Journal of Theoretical and Computational Chemistry

A DFT study of homonuclear X₂ ($\mathrm{\text{X}}=\mathrm{\text{Ge}}$, As, Se, Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn) is presented using PBEO exchange (xc) functional which is a mixing of Perdew–Burke–Ernzerhof (PBE) and Hartree Fock (HF) exchange energy. However, we used cc-pVXZ and aug-cc-pVXZ basis sets where X is maximum angular momentum number in basis set. Convergence pattern of binding energy with respect to basis set was observed. Two-point extrapolations to complete basis set (CBS) limit were applied to speed up convergence and decrease the basis set incompleteness error (BSIE). Counterpoise correction (CP) method was utilized to alleviate basis set superposition errors (BSSE). Both CP-corrected and uncorrected binding energies were obtained and compared with the experimental and theoretical binding energy values in literature.

B3LYP/6-31G($d$, $p$) quantum mechanical calculations were conducted to study polyvinyl chloride (PVC) and PVC with metal oxides (ZnO and CuO). Accordingly, model molecules for PVC; PVC/$x$ZnO; PVC/$y$CuO and PVC/$x$ZnO/$y$CuO, where $x$ and $y=1$, 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 ($d$, $p$) and indicated that there are two bands at 2990cm${}^{-1}$ and 2975cm${}^{-1}$ in comparison with Fourier transform infrared spectrum (FTIR).

In this study, the mechanism underlying acetylcholinesterase (AChE) and 5-lipoxygenase (LOX) inhibition by two novel alkaloids, beilschglabrine A and beilschglabrine B, as well as their interaction footprints on the binding pockets were investigated. The results showed that beilschglabrine A and beilschglabrine B inhibit both AChE and LOX in a competitive manner by binding to their active sites thereby interfering with substrate access. The interaction of the alkaloids with the enzymes was favorable and stable with low binding energy values which correlate well with their IC${}_{50}$. The depicted molecular interaction, structure-energetic pattern and binding conformations confirmed that beilschglabrine A is more potent than beilschglabrine B. The differences in the binding pose and potency of the alkaloids is occasioned by an extra methyl moiety on beilschglabrine B. The chemical scaffold of the alkaloids respected Lipinski’s rule of five and may be relevant in the development of new anti-inflammatory and anti-neurodegenerative disease drugs acting via AChE and LOX inhibition.

The movement of quantum particles between distinct spatial regions is an essential feature of nanoscale devices. Consequently, theoretical methods for characterizing the transit time associated with this movement may aid in identifying and refining nanoscale systems with desirable transport properties. Herein, we explore the utility and range of validity of a recently reported probabilistic method for quantifying the timescale of quantum particle transit. The method is applied to intramolecular proton transfer in dicarbonyl compounds, and electron transfer in donor-bridge-acceptor molecules. Direct comparison is made between statistical predictions of proton and electron transfer times and corresponding transfer times deduced from the previously reported experimental observables. Insights provided by the method into the path of flow of probability density are discussed.