Journal of Theoretical and Computational Chemistry

New cytotoxic steroidal glycoside of methanol extract from Kochia prostrata ($L.$) Schrad was investigated in this study. Bio-guided isolation from ethylacetate fraction of whole plant afforded steroidal glycosides named as 5-ene-dimethylcholest3-O-$\beta$-D-glucoside (Kochioside 1A₁), 5-ene-methylcholest3-O-$\beta$-D-glucoside (Kochioside 2A₁) and 4-ene-dimethylcholest3-O-$\beta$-D-glucoside (Kochioside 3A₁). Their structures were assigned by physical and spectroscopic methods. Kochiosides 1A₁–3A₁ showed inhibitory potential against brine shrimp lethality bioassay with etoposide standard drug. The new steroidal glycoside kochiosides 1A₁–3A₁ showed inhibition values of 8.3201, 8.8205 and 8.2310$\mu$g/mL, respectively with ${\text{LD}}_{50}$ compared to standard etoposide ${\text{LD}}_{50}$ (7.4625$\mu$g/mL) drug. Moreover, six new derivatives were designed by substituting the –NH₂ and –OCH₃ at R1, R2 and R3 positions in the isolated compounds. Herein, various molecular descriptors, frontier molecular orbitals (FMO), electron affinity, ionization potential and molecular electrostatic potential (MEP) were carried out to understand the active sites and biological active nature of the new cytotoxic steroidal glycoside kochiosides. The effect of electron donating groups (–NH₂ and –OCH₃) was also investigated on the structural parameters and electronic properties in gas and solvent (DMSO) phases. The energy gap, MEP and reactivity descriptors values demonstrate that the kochioside 3A₁ retains good reactivity, which is in good agreement with current experimental studies.

Because of their availability, lower cost, biodegradability, respect for health, environmental standards and their extremely high efficiency [Benmessaoud Left D, Zertoubi M, Irhzo A, Azzi M, Revue: Huiles et extraits de plantes comme inhibiteurs de corrosion pour différents métaux et alliages dans le milieu acide chlorhydrique, J Mater Environ Sci 4:855–866, 2013], the green corrosion inhibitors are currently the most sought after candidates. The ultimate aim of this work is to study the selectivity and reactivity of a series of three molecules, namely Cytisine, Dehydro-Cytisine and N-methyl Cytisine which are the major constituents of Retama monosperma seeds alkaloid extract (AERS) as eco-friendly inhibitors of corrosion of carbon steel in acidic medium HCl (1M), using the density functional theory (DFT) at B3LYP/aug-cc-pvdz levels. Indeed, this alkaloid extract AERS has proven experimentally its corrosion inhibitory power for carbon steel in 1 M HCl even at lower concentration (94.42% at 400mg/L). Besides, its adsorption on the steel surface in 1 M HCl solution followed Langmuir’s isotherm [El Hamdani N, Fdil R, Tourabi M, Jama C, Bentiss F, Alkaloids extract of Retama monosperma (L.) Boiss. seeds used as novel eco-friendly inhibitor for carbon steel corrosion in 1 M HCl solution: Electrochemical and surface studies, Appl Surf Sci 357:1294–1305, 2015, doi: 10.1016/j.apsusc.2015.09.159; El Hamdani N, Contribution a la valorisation des parties aériennes de Retama Monosperma, phytochimie, activités antimicrobiennes et propriétés anticorrosives, Universite Chouaib Doukkali Faculte des sciences El jadida, 2015]. Herein, the major aim of this work is to investigate the likelihood of the carbon steel corrosion being inhibited by the protonated species in the aqueous acidic solution. For this purpose, after proving that the most favorable protonation site for protonation was N9, we have evaluated the structural, global and local reactivity descriptors, partial atomic charge in terms of Natural bond orbital (NBO) of the three protonated inhibitors at the level of N9, which are the most stable in the aqueous acidic solution. NBO analysis and the thermodynamic properties such as entropy, enthalpy, heat capacity and Gibbs free energy were also done. In conclusion, it was observed that three protonated molecules showed a high propensity to adsorb to the mild steel surface with a priority of the molecule d-CytN9H+.

Recently, an anthraquinone-supported thiourea group linking a 1-aza-18-crown-6 macrocycle L has been the subject of extensive attention due to the perfect affinity towards metal cations. This work systematically researched the effects of different metal cations ($\mathrm{\text{M}}={\mathrm{\text{Na}}}^{+}$, ${\text{K}}^{+}$, ${\text{Mg}}^{2+}$, ${\text{Ca}}^{2+}$, ${\text{Cu}}^{+}$ and ${\text{Ag}}^{+}$) on the second-order nonlinear optical (NLO) properties of macrocycle L by density functional theory (DFT). DFT calculations revealed that the values of first hyperpolarizabilities (${\beta }_{\mathrm{\text{tot}}})$ decrease significantly when alkaline earth metal cations (${\text{Mg}}^{2+}$ and ${\text{Ca}}^{2+}$) were injected into macrocycle L due to the smaller charge transfer (CT) transition and larger transition energy. Conversely, the variations of ${\beta }_{\mathrm{\text{tot}}}$ values in alkali metal cations (${\text{Na}}^{+}$ and ${\text{K}}^{+})$ and transition metal cations (${\text{Cu}}^{+}$ and ${\text{Ag}}^{+}$) derivatives are not obvious compared to the ${\beta }_{\mathrm{\text{tot}}}$ value of macrocycle L. Therefore, the NLO properties of macrocycle can be effectively regulated by alkaline earth metal cations. Furthermore, we found that the ${\beta }_{\mathrm{\text{tot}}}$ value of anion-controlled complex Na(L)(ClO₄) is larger than that of L*Na⁺ complex because the anion ${\text{ClO}}_4^{-}$ improves the planarity of anthraquinone-supported thiourea group leading to the enhancement of the CT ability. In addition, the influence of frequency-dependent on the first hyperpolarizabilities is weak for the current systems. Hence, we look forward to the conception of this work will offer a fundamental guideline and reference for further research for novel NLO materials.

We have explored detailed linear and nonlinear optical properties of push-pull systems bearing thienothiophene and dithienothiophene spacers. By using density functional theory (DFT), frequency-dependent strategies were applied to examine the polarizability ($\alpha )$ and hyperpolarizability ($\beta$ and $\gamma )$. The set of global and range-separated hybrid functionals with different Hartree–Fock (HF) exchange percentage at two basis sets cc-pVDZ and cc-pVTZ were used to evaluate the nonlinear optical (NLO) properties. The observed trends in the absorption maxima supported by perturbation potential analysis; as the absorption maxima increases, the respective amplitude potential decreases. For the investigated compounds, $\pi$-conjugation along with the type of substituted acceptor plays a crucial role in the enhancement of NLO properties. The presence of acceptor group and length of conjugation increase between the D and A group; the first- and second-order intrinsic hyperpolarizability increases, leads to enhanced first- as well as second-order hyperpolarizability. Bond length alternation (BLA)/bond order alteration (BOA) exploration suggested that compounds attain cyanine limit. The trends in NLO properties for investigated compounds are supported by chemical reactivity descriptors, hardness and hyperhardness analysis. The polarizability is linearly correlated with the hyperpolarizability parameters ($\beta$ and $\gamma )$ and shows a good regression coefficient by figures of merit analysis.

Although the conversion of furfural to formic acid oxidized by H₂O₂ in formic acid is very high, the molecular mechanism remains unknown. This work describes the entire reaction process of the condensation reaction based on the density functional theory (DFT). It is found that H acts as a shuttle throughout most of the basic reaction steps during this transformation. Besides, Baeyer–Villiger oxidation and Baeyer–Villiger rearrangement are also discovered during this process with the opening of furan ring following afterward. The reactants, products and intermediates in the reaction process are optimized; all possible reaction paths are considered as well as the energy barriers to be overcome at each step. Thermochemical data concerned with the conversion of furfural to maleic acid showed that the maximum energy barrier at 378.15K was 39.83kcal/mol. The results of this study do not only correspond with the existing conclusions about the reaction in question from previous research but also supplement to the study of the pathways and mechanisms of the reaction, which can provide reference and guidance for further research, both experimentally and theoretically.

In the present work, we have studied the 2-hydroxy 2-methyl propiophenone (2H2MPP) theoretically as well as experimentally. The optimized molecular structure has been obtained by the density functional theory (DFT), second-order Moller–Plesset perturbation theory (MP2) and Hartree Fock (HF) in the gas phase as well as in different media like ethanol, DMSO and heptane. FT-IR and FT-Raman spectra were computed as well as recorded and fundamental vibrational wavenumbers were assigned. The electronic absorption spectra were calculated by employing the time-dependent density functional theory (TD-DFT) to get the information about excitation energies, oscillator strength and excited state geometries in gas phase and in different solvent media. Chemical activity and chemical stability obtained by HOMO-LUMO studies using a HF/6-31$+$G and MP2/6-311$++$G calculations. The chemical interpretation of hyperconjugation interactions obtained by the Natural Bond Orbital (NBO) analysis. Moreover, electrostatic potential (ESP) calculations performed to get the visual representation of relative polarity of molecule. Thermodynamic parameters like enthalpy, entropy, heat capacity, and Gibbs free energy computed with varying temperature from 10K to 500K. The aim of the current investigation is to find out the quantum chemical properties of the title compound which show an active role in the pharmaceutical and printing industries.

The processes of population transfer in the ground electronic state of HCl molecule through the three transition schemes are investigated by numerically solving the time-dependent Schrödinger equation. Two harmonic pulses are employed to induce population transfer and the relative phase of the two pulses can control the final population distributions. In the ladder transition scheme, the variation range of the target population with the relative phase is nearly 100% which is larger than that in the multi-photon transition scheme. It is more efficient for the mixed transition scheme to control population transfer between the initial and target states by using the relative phase. Comparing with the multi-photon and ladder schemes, the transition probability of the target population is more sensitive to the two pulse amplitudes in the mixed transition scheme.