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In this paper, we have studied the effect of asymmetry and bent-core LC phases (B1 & B2) on electro-optical and thermal parameters utilizing the DFT/B3LYP/6-31G** technique on 4-((3-((4-(((4-(decyloxy)phenyl)imino)methyl)benzoyl)oxy)phenoxy)carbonyl)phenyl-4-(alkyloxy)benzoate [DIBCPnB] homologous molecules. Raman spectra of homologous molecules (10a-10g) have been analyzed using the DFT method, while UV-vis spectra are analyzed by both the TD-DFT and ZINDO methods. The effects of asymmetry and phase on electro-optical properties e.g. dipole moment, total energy, anisotropic polarizability, mean polarizability and molar refractivity, as well as global parameters like electronegativity, electron affinity, ionization potential, electrophilicity index, chemical hardness, electron-accepting capability and electron-donating capability have been investigated. The dependence of thermal properties on asymmetry and phases has been examined. This study reveals that asymmetry does not affect total energy, polarizability and molar refractivity. We report that homologues exhibiting the B1 phase possess lower anisotropic polarizabilities than those in the B2 phase. [ABSTRACT FROM AUTHOR]

Four aliphatic amino acids—α-aminobutyric acid (AABA), β-aminobutyric acid (BABA), α-aminoisobutyric acid (AAIBA) and β-aminoisobutyric acid (BAIBA) were investigated in water as a solvent by two quantum chemical methods. B3LYP hybrid version of DFT was used for geometry optimization and a full vibrational analysis of neutral molecules, their cations and anions in the canonical and zwitterionic forms (6 forms for each species). Ab initio DLPNO-CCSD(T) method was applied in the geometry pre-optimized by B3LYP. Calculated molecular descriptors involve dipole moment, quadrupole moment, dipole polarizability, energy of zero-point vibration and total entropic term which enter the standard Gibbs energy. In addition, a set of collective electronic and thermodynamic properties associated with redox process were evaluated: ionization energy, electron affinity, chemical hardness, molecular electronegativity, electrophilicity index, absolute oxidation and reduction potentials. A mutual comparison of these structural isomers including γ-aminobutyric acid (GABA) shows high degree of similarity in molecular descriptors. However, cluster analysis of 12 electro neutral, linear and branched amino acids with 2 – 6 carbon atoms discriminates them into five clusters. It is found that the electrophilicity index correlates with the absolute reduction potential along a straight line (24 items). The reduction potential for canonical structure varies between 1.21 V (glycine) and 1.45 V (AABA) whereas for the zwitterionic form it is visibly lower 0.52–1.11 V. The highest absolute reduction potential > 1.43 V is shown by α-amino acids: α-alanine, AABA (homoalanine) and AAIBA having 2-methyl or 2-ethyl functional group. The calculated absolute oxidation potential correlates with the adiabatic ionization energy and can be used as a criterion of the antioxidant capacity. According to thermodynamic data, the SPLET mechanism of the electron-proton coupled transfer is favored over the alternative SET-PT mechanism. This work contributes to the creation of a database of molecular properties of amino acids based on the same method and basis set. [ABSTRACT FROM AUTHOR]

Context: Heparan sulfate (HS) linear polysaccharide glycosaminoglycan compound is linked to components from the cell surface and the extracellular matrix. HS mediates SARS-CoV-2 infection through spike protein binding to cell surface receptors and is required to bind ACE2, prompting the need for electronic structure and molecular docking evaluation of this core system to exploit this attachment in developing new derivatives. Therefore, we have studied five molecules based on HS using molecular docking and electronic structure analysis. Non-covalent interaction analysis shows hydrogen bonding and van der Waals interactions in the binding to RBD-ACE2 interface and 3CLpro. SDM3 and SDM1 molecules present the lowest gap, including solvent effect under 154.6 kcal/mol, and exhibit the most reactivity behavior in this group, potentially leading to enhanced interaction in docking studies. Methods: Heparan sulfate and four derivatives were optimized using B3LYP functional with two basis sets 6–31 + G(d,p) and def2SVP. Electronic structure was used to explore the main interactions and the reactivity of these molecules, and these optimized structures were used in the molecular docking study against 3CLpro, RBD, and ACE2. [ABSTRACT FROM AUTHOR]

The reaction of propargyl chloride with ethane-1,2-bis(thiolate) in the system hydrazine hydrate–potassium hydroxide has been simulated using the combined CCSD(T)/6-31+G*//B3LYP/6-311++G** approach. Elementary steps of the process and possible heterocyclization pathways of the primary intermediates have been identified. Under experimental conditions (40–42°C, 6 h), the title reaction produced 25% of 2-methyl-5,6-dihydro-1,4-dithiine and 24% of 4,7-dithiadeca-2,8-diyne. No cyclic products were formed at –10 to –15°C. [ABSTRACT FROM AUTHOR]

Aim: A protocol relying on quantum chemical calculations to assist prioritization of phenolic compounds as antioxidants in terms of hydrogen atom donation efficiency is presented. The use of reference compounds, an important metrological issue for a future harmonization and standardization of computational approaches in research is also considered. Methods: A density functional theory (DFT) approach, namely B3LYP/6-311G++(2d,2p)//B3LYP/6-31G in the gas-phase was used for structure optimization, frequency calculation and single point energy (SPE) calculation to obtain the bond dissociation enthalpy (BDE) value of the most active O-H of olive oil phenols. For some of them used as a test set and for comparison, BDE values were calculated using three more approaches, M05-2X in the gas-phase, Becke three-parameter Lee-Yang-Parr (B3LYP) and implicit solvent effects (n-heptane to model bulk oils) with the integral equation formalism version of the polarizable continuum model (IEF-PCM), Minnesota 05 functional with double nonlocal exchange (M05-2X) at a single step using 6-31G+(d) basis set and solvation model density (SMD) as solvation model. Phenol and Trolox were used as reference compounds for ΔBDE calculation. Results: The proposed protocol was faster by 1.35-, 1.6-, and 8.3-fold respectively than the other three and provided almost the same activity trend application to other type of olive oil phenols indicated that prioritization based on ΔBDE values was in accordance with the limited existing experimental findings in bulk oils, and the order of activity was generally in agreement with the structure-antioxidant activity criteria. Conclusions: Present findings highlighted the usefulness of quantum chemical calculations as a tool to screen/prioritize molecules with an established structure saving experimental effort and waste production. The expression of results relatively to phenol and Trolox BDE values, may assist comparisons among research findings and facilitate standardization. Based on the findings hydroxytyrosol and related compounds should be efficient hydrogen atom donors compared to other potent virgin olive oil phenols.

Abstract This study examined the functionalization of graphene with easily ionizable elements, such as lithium, and subsequently its interaction with the biopolymer sodium alginate (SA), to highlight its potential for biomedical applications. Utilizing Density Functional Theory (DFT), the research comprehensively investigated the structural, electronic, and spectroscopic properties of these graphene-based composites. The electronic properties of functionalized graphene were investigated using DFT at the B3LYP/6-31G(d,p) level. Among the various configurations studied, graphene exhibited weak interaction with two lithium atoms, displaying the highest reactivity in terms of total dipole moment (TDM) at 5.967 Debye and a HOMO/LUMO energy gap (ΔE) of 0.748 eV. Electrostatic potential mapping revealed that graphene when enhanced with lithium and three units of SA, exhibited an augmented potential density on its surface, a finding corroborated by other investigated physical properties. Notably, the configuration of graphene/3SA/Li, with weak interaction occurring at two side carbons, demonstrated the highest reactivity with a TDM of 15.509 Debye and ΔE of 0.280 eV. Additionally, a shift in the spectral characteristics of graphene towards lower wavenumbers was observed as lithium and SA interacted with the graphene substrate. The PDOS plot for Graphene/3SA/Li, showed the highest contribution in the HOMO orbitals was equally from lithium, sodium, hydrogen, and oxygen, while the lowest contribution was from carbon. This computational analysis provides comprehensive insights into the functionalized graphene systems, aiding in their further development and optimization for practical biomedical use.

In present work, using the double layer ONIOM methodology, we simulated the stages of initiation and growth of the polymer chain during the polymerization of butadiene on a neodymium‐based Ziegler–Natta catalyst. The DFT methods B3LYP and PBE0 in combination with the Def2‐TZVP atomic basis set were used as high‐level methods in ONIOM. Grimme's semi‐empirical XTB1 method was used as a low‐level method. In our previous work, the mechanism of butadiene polymerization on a neodymium‐containing Ziegler–Natta catalyst was studied in detail. The polymerization activation energy of 61 kJ/mol was found to be slightly higher than the experimentally determined values of this parameter. In the present work, the influence of a high‐level method and a model of taking into account dispersion interactions on the quality of calculation of activation parameters of the polymerization reaction was studied. Experimental activation energy for the polymerization of dienes in the presence of Ziegler–Natta catalysts is in the range of 30–60 kJ/mol, but neodymium‐based catalysts have an activation energy somewhat closer to the lower limit of this range. For comparison, semi‐empirical Grimme models D3 and D4 were used. It has been established that the both models reveal within the B3LYP method the activation energy practically the same, while within the PBE0 method it decreases to 41 kJ/mol. Thus, using the PBE0 as a high‐level method within the ONIOM methodology and taking into account dispersion interactions within the D4 model leads to results in much better agreement with experimental data. [ABSTRACT FROM AUTHOR]

Context: Allene (H2C = C = CH2) and propyne (CH3-C≡CH) are important compounds in the combustion chemistry. They can be created from the reaction of proparyl radicals with water. In this study, therefore, a computational study into the C3H3 + H2O potential energy landscape has been carefully conducted. The computed results indicate that the reaction paths forming the products (allene: CH2CCH2 + •OH) and (propyne: HCCCH3 + •OH) prevail under the 300–2000 K temperature range, where the latter is much more predominant compared to the former. However, these two products are not easily formed under ambient conditions due to the high energy barriers. In the 300 – 2000 K temperature range, the branching ratio for the propyne + •OH product declines from 100 to 86%, whereas the allene + •OH product shows an increase, reaching 14% at 2000 K. The overall bimolecular rate constant of the title reaction can be presented by the modified Arrhenius expression of ktotal = 1.94 × 10–12 T0.14 exp[(-30.55 kcal.mol−1)/RT] cm3 molecule−1 s−1. The total rate constant at the ambient conditions in this work, 2.37 × 10–34 cm3 molecule−1 s−1, was found to be over five orders of magnitude lower than the total rate constant of the C3H3 + NH3 reaction, 7.98 × 10–29 cm3 molecule−1 s−1, calculated by Hue et al. (Int. J. Chem. Kinet. 2020, 4(2), 84–91). The results in this study contribute to elucidating the mechanism of allene and propylene formation from the C3H3 + H2O reaction, and they can be used for modeling C3H3-related systems under atmospheric and combustion conditions. Methods: All the geometric structures of the C3H3 + H2O system were optimized by the B3LYP method in conjunction with the 6–311 + + G(3df,2p) basis set. Single-point energies of these species were calculated at the CCSD(T)/6–311 + + G(3df,2p) level of theory. The CCSD(T)/CBS level has also been used to compute single-point energies for the two major reaction channels (C3H3 + H2O → allene + •OH and C3H3 + H2O → propyne + •OH). Rate constants and branching ratios of the key reaction channels were calculated in the 300–2000 K temperature interval using the Chemrate software based on the transition state theory (TST) with Eckart tunneling corrections. [ABSTRACT FROM AUTHOR]

This study examined the functionalization of graphene with easily ionizable elements, such as lithium, and subsequently its interaction with the biopolymer sodium alginate (SA), to highlight its potential for biomedical applications. Utilizing Density Functional Theory (DFT), the research comprehensively investigated the structural, electronic, and spectroscopic properties of these graphene-based composites. The electronic properties of functionalized graphene were investigated using DFT at the B3LYP/6-31G(d,p) level. Among the various configurations studied, graphene exhibited weak interaction with two lithium atoms, displaying the highest reactivity in terms of total dipole moment (TDM) at 5.967 Debye and a HOMO/LUMO energy gap (ΔE) of 0.748 eV. Electrostatic potential mapping revealed that graphene when enhanced with lithium and three units of SA, exhibited an augmented potential density on its surface, a finding corroborated by other investigated physical properties. Notably, the configuration of graphene/3SA/Li, with weak interaction occurring at two side carbons, demonstrated the highest reactivity with a TDM of 15.509 Debye and ΔE of 0.280 eV. Additionally, a shift in the spectral characteristics of graphene towards lower wavenumbers was observed as lithium and SA interacted with the graphene substrate. The PDOS plot for Graphene/3SA/Li, showed the highest contribution in the HOMO orbitals was equally from lithium, sodium, hydrogen, and oxygen, while the lowest contribution was from carbon. This computational analysis provides comprehensive insights into the functionalized graphene systems, aiding in their further development and optimization for practical biomedical use. [ABSTRACT FROM AUTHOR]

In this work, the abilities of Ni-C38, Ni-B19N19 and Ni-Si38 for oxygen reduction reaction (ORR) are investigated. The Eformation of Ni-C38, Ni-B19N19 and Ni-Si38 are −4.72, −5.96 and − 6.43 eV. The Ni-Si38 has higher ability to adsorb the ORR species than Ni-C38 and Ni-B19N19. The mechanism 1 is acceptable pathway for oxygen reduction reaction (ORR) on Ni-C38, Ni-B19N19 and Ni-Si38. The ΔGreaction of HO*-catalyst-O* → O* on Ni-C38, Ni-B19N19 and Ni-Si38 are −1.55, −1.59 and − 1.72 eV. The ΔGreaction of ORR on Ni-C38, Ni-B19N19 and Ni-Si38 are more negative than ΔGreaction of ORR on Pt-based catalysts, Si nanocages and C nanocages in previous works. The overpotential of ORR on Ni-C38, Ni-B19N19 and Ni-Si38 are 0.31, 0.36 and 0.42 V which are lower than overpotential of ORR on Pt catalysts. [ABSTRACT FROM AUTHOR]

The electronic features of chemically functionalized graphene quantum dots (GQDs) are investigated using density functional theory (DFT). The fabrication of nanoscale devices needs to enhance- the electronic performance of customized GQDs, which is crucial in many applications. GQDs can be used as a model with the molecule C24H12. We investigated the effects of adding metalloid impurities) boron B, silicon Si, germanium Ge, and arsenic As) on the structure and electronic properties of the dots at the B3LYP/6–31 level using the Gaussian 09 program package. The obtained results show efficient adding impurities B, Si, Ge, and As on the structure and electronic properties of GQDs, where it is noted that the energy gap change with -3.085, -12.340, -13.907, and -66.846 %, respectively.These results not only advance our knowledge of the mechanisms behind chemical doping, which may change the electronic features of quantum dots, but they also provide support for the development of nanodevices that have better electronic performance. As observed with As/GQD, it is anticipated that this system, which has the lowest possible chemical hardness values, will function as an effective corrosion inhibitor.

Background. Menthol is used in chemistry and pharmaceuticals. Understanding its structure and properties is revealed by the quantum-chemical method. Purpose. To study the properties of menthol by the quantum-chemical method. Methodology. Quantum-chemical calculations using the Gaussian 09 software package and the 3-21G, 6-31G and 6-311G basis sets. The DFT, Unrestricted and B3LYP methods, Avogadro 1.2.0 and GaussView 6.0.16 programs were used. Originality. For the first time, the structural and electronic properties of menthol, previously unknown features of the molecular structure of menthol have been revealed, which opens up prospects for its wider use. Findings. - bond length, charge distribution in the menthol molecule; - molecular orbital analysis (HOMO), (LUMO); - electrostatic potential of menthol. [ABSTRACT FROM AUTHOR]

The LaTiO3 perovskite (where Ti is in a d1 state) is investigated by using an all electron Gaussian basis and many functionals, ranging from pure GGA (PBE), to hybrids (full range, B3LYP and PBE0, and range separated, HSE06) to Hartree Fock. Recently, Varignon et al. (Phys. Rev. Res 1, 033131, 2019), showed that, when GGA+U or HSE06 are used, a metallic solution and fractional occupancy of the t2g subshell are obtained. Here, it is shown that when a full range hybrid functional is used, an integer occupancy is obtained, as suggested by the Jahn-Teller theorem. When the exact exchange percentage varies from 0 to 100, the system is insulating when it exceeds 20. By reducing progressively the symmetry from cubic down to orthorhombic, the relative importance of the Jahn-Teller deformation and of the rotation of the octahedra is explored. [ABSTRACT FROM AUTHOR]

The LaTiO3 perovskite (where Ti is in a d1 state) is investigated by using an all electron Gaussian basis and many functionals, ranging from pure GGA (PBE), to hybrids (full range, B3LYP and PBE0, and range separated, HSE06) to Hartree Fock. Recently, Varignon et al. (Phys. Rev. Res 1, 033131, 2019), showed that, when GGA+U or HSE06 are used, a metallic solution and fractional occupancy of the t2g subshell are obtained. Here, it is shown that when a full range hybrid functional is used, an integer occupancy is obtained, as suggested by the Jahn-Teller theorem. When the exact exchange percentage varies from 0 to 100, the system is insulating when it exceeds 20. By reducing progressively the symmetry from cubic down to orthorhombic, the relative importance of the Jahn-Teller deformation and of the rotation of the octahedra is explored. [ABSTRACT FROM AUTHOR]

Some long chain fatty acid oxadiazoles are good corrosion inhibitors in the presence of acidic environment for mild steel and N80 steel surfaces. In this study, 2-undecane-5-mercapto-1-oxa-3,4-diazole-2-thiol(thione) (UMOD), 2-heptadecene-5-mercapto-1-oxa-3,4-diazole-2-thiol(thione) (HMOD) and 2-decene-5-mercapto-1-oxa-3,4-diazole-2-thiol(thione) (DMOD) as neutral and protonated forms in gas and aqueous phases have been studied using density functional theory (DFT) with the B3LYP/6-311G level calculations. In addition, the inhibitive effect of studied inhibitors against the corrosion of neutral iron surface is studied in aqueous phases by means of same calculation method. The calculations were made for both molecule structures, since the molecules examined show thione-thiol tautomerism. Optimized molecular structure, highest occupied molecular energy level (EHOMO), lowest unoccupied molecular energy level (ELUMO), the energy gap between ELUMO and EHOMO (∆ELUMO–HOMO), electronegativity (χ), hardness (η), softness (σ), dipole moment (μ), the fraction of electrons transferred from the inhibitor to metal surface, surface (ΔN) were correlated to corrosion inhibition efficiency of studied compounds and the results were interpreted. Molecular electrostatic potential (MEP) distributions of some long chain fatty acid oxadiazoles have been studied. [ABSTRACT FROM AUTHOR]

Manufacturing of clean energy is an important topic of research for modern life. This paves the way toward investigating easy manufacturing; high-performance energy storage materials. In this sense, conducting polymers such as polyaniline (PANI) are modified with graphene (G) then bound with poly vinylidene fluoride (PVDF) and poly tetrafluoro ethylene (PTFE) to enhance their electronic properties to be used as electrode material in energy storage applications. Furthermore, molecular modeling based on density functional theory at B3LYP/LanL2DZ level of theory was utilized to study the interaction between PANI; G; PVDF and PTFE. Some important properties are calculated such as the total dipole moment (TDM), HOMO/LUMO energy gap (ΔE), and molecular electrostatic potential (MESP). TDM of PANI was found to be 3.994 Debye and increased to 6.010, 9.012, and 9.822 Debye for PANI/G/PTFE, PANI/G/PVDF/PTFE, and PANI/G/PVDF, respectively. ΔE of PANI is 4.353 eV and decreased because of the interaction of PANI with G and polymer binders to reach 3.507, 3.095, and 2.127 eV for PANI/G/PTFE, PANI/G/PVDF, and PANI/G/PVDF/PTFE, respectively. From MESP result, the reactivity and electronic properties increased with the interaction of PANI with G and polymer binders. PANI/G/PVDF/PTFE composite was dedicated as the most suitable candidate for electrode material for many applications. [ABSTRACT FROM AUTHOR]

The analysis to plan for high-efficiency with affordable molecules such as coumarin, prop-1-ene with 2-cyano-N-hydroxyacrylamide (A1), 2-cyanoprop-2-enedithioic acid (A2), 1-cyanovinylphosphonic acid (A3) and 1-cyanoethenesulfinic acid (A4) are one of the most important aspects of improving the non-linear optical (NLO) property besides dye-sensitized solar cells (DSSCs) applications. NKX-2311 has been taken as a literature molecule, it contains coumarin as a donor moiety (D), prop-1-ene as a π-spacer (π) and cyanoacrylic acid as an acceptor moiety (A). The three fragments that make up the D-π-A structure. The family of A1-A4 metal-free organic coumarin NKX-2311 dye derivatives have examined for applications involving optoelectronics in this research. Density functional theory (DFT) and time-dependent DFT (TD-DFT) techniques utilizing quantum chemical calculations, the molecular electronic structures, ultra-violet visible (UV–Vis) absorption, transition density matrix (TDM), electron–hole mobilities (reorganization energies) and photovoltaic (PV) characteristics of the A1-A4 sensitizers have been calculated. For optoelectronic devices, the effect of chemical alteration on the UV–Vis spectra about PV parameters of the NKX-2311 were illustrated. The performance of hybrid functionals such as B3LYP, CAM-B3LYP and ωB97XD was assessed to compare with the absorption wavelength of NKX-2311. The B3LYP method and NKX-2311 have had a superior fit based on the selected functionals. Consequently, the B3LYP/6-31G(d) theory has been used to study the excited state computations of A1-A4 dyes at UV–Vis wavelengths. The findings demonstrate that A2 dye has a smaller energy gap and that UV–Vis spectra were constantly redshifted. According to the computational outcomes, the A1-A4 sensitizers can respond positively to the processes of dye regeneration and electron injection based on their lowest unoccupied and highest occupied molecular orbitals (LUMOs and HOMOs), respectively. A2 dye has the greatest hole mobility due to its lowest λ + value of 0.1701 eV, while A1 dye has extreme electron mobility due to its lowest λ - value of 0.2273 eV. The NLO property of molecules A1-A4 has been calculated by two ways such as polarizability and first-order hyperpolarizability. The most promising candidate for NLO performance has been identified as the dye with computed values of A2. The results would serve as a useful resource for any upcoming demands and also more advantageous for obtaining optoelectronic applications. [ABSTRACT FROM AUTHOR]

At the B3LYP/6-311++G(3df,3pd) level of theory, the spatial and electronic structure of the cyanide, cyanate and thiocyanate ambident anions has been studied. By means of the natural bond orbital (NBO) analysis and the R. F. W. Bader's quantum theory "Atoms in Molecules" (QTAIM), the electron density delocalization and topological properties in the above anions have been investigated. The distribution of electron density (NBO, QTAIM) in the XCN- (X = O, S) anions is reflected by the scheme [X C N]-. The relative contribution of the hypothetical structure X=C=N- to the resonance hybrid -X-C=N X=C=N- is higher in the case of X = O. The degree of the C=N or C N bond triple character and bond strength changes in the following series of anions: CN- > SCN- > OCN-. The occupancy of the lone electron pair (LP) orbital of the nitrogen atom in the above anions is close to 2, and the LP orbital is sp-hybridized. Condensed K. Fukui functions for the electrophilic attack have been evaluated. Local hardness of the donor reaction centres: N > C (CN-), O > N (OCN-), N > S (SCN-). The regioselectivity of the homolytic oxidative coupling reactions of CN-, OCN-, SCN- has been substantiated. [ABSTRACT FROM AUTHOR]

Context: We have performed a detailed MM and DFT investigation of neutral water clusters (H2O)n (n = 3–12). Our results show the trend of interaction energies in these clusters as a function of the size of the cluster. They show that the H-bond strength increases with cluster size and that the model of water is better described if two different partial charges are used on the hydrogen, depending on whether hydrogen is H-bonded or not. The average binding enthalpy change due to the formation of H-bonds between water molecules is found to be − 25.9 kJ mol−1 at B3LYP/aug-cc-pVDZ level of theory. We observe the formation of cyclic H-bonded networks through the analysis of frontier orbitals and IR vibrational frequencies spectra. For the water cluster with n = 11, we observe an unusual reduction of the bandgap indicative of a cyclic H-bonded network. Methods: Calculations were performed with the MMFF94 force field and the B3LYP method using various large basis sets. Molecular orbital diagrams and population analysis were done using standard tools in Gaussian. [ABSTRACT FROM AUTHOR]

To identify promising compounds and to develop a potent non-linear optical material, the molecule 1-acetyl-2-(4-ethoxy-3-methoxyphenyl) cyclopropane (AEMC) was selected. FTIR and FT-Raman spectroscopy techniques were employed to predict the functional groups and vibrational modes of AEMC. Gaussian 09 W software was utilised to analyse the parameters of the optimised title compound. Reactive sites were forecasted using MEP plots. To clarify the chemical significance of the molecule, ELF and LOL are utilised. Furthermore, the presence of interactions within the molecule is confirmed by RDG analysis. The strong and weak hydrogen bonds between the non-bonding atoms of AEMC are studied with the aid of AIM analysis. Additionally, the material's capacity to produce non-linear effects (NLO) was ascertained by examining the linear polarizability and first order hyper polarizability values.

The compound (1-methyl)-2-(2-arylaminothiazol-4-yl)benzimidazole has been characterized by IR spectra. The theoretical calculations of the mentioned compound have been carried out using the more popular density functional theory method, Beck's-3-parameter-Lee Yang Parr (B3LYP) in 6-31G basic set. Optimized geometries of the molecule have been described and collated with the experimental values. The experimental atomic charges demonstrate adequate concurrence with the theoretical prediction from DFT. Theoretical spectral values have been interpreted and compared with FT-IR spectra. The IR spectra are obtained and assigned by vibrational analysis. The Mulliken population analysis on atomic charges has been computed using DFT calculation. A correlation between the theoretical and the experimental spectra has been achieved. The calculated HOMO and LUMO energy gaps also confirm that charge transfer occurs within the molecule. The compound C2 has highest activity against Hep-C cell line. Five membered heterocyclic moieties have been proved to posses strong biological activities. Hence a series of noval benzimidazolyl thiazoles have been synthesized by multi-step reaction from 2-acetyl benzimidazole and hydroxylamine hydrochloride as starting materials and structure characterized by NMR and mass spectroscopy. The antioxidant activities of the derivatives have been determined by DPPH scavenging assay. The synthesized compounds show remarkable antioxidant activity. They show excellent anticancer activity. [ABSTRACT FROM AUTHOR]

In this research work, bicomponent structures of salicylic acid were synthesized by reflux condition. The cofomers used were 1-10-phenanthroline, 5-chlorobenzotiazole, and 2-amino-5-methylpyridine. The yield of resultant crystals was calculated at about 60–70 %. It was concluded that bicomponent polymorphs 1–3 were formed by treating salicylic acid (SA) with 10-phenathroline (1-10-Phen), 5-chlorobenzotiazole (5-ClB), and 2-amino-5-methylpyridine (2A-5M-P) respectively. The intermolecular interactions were further confirmed by their computational studies. Molecular docking revealed that the binding nature of salicylic acid can be tuned upon cocrystallization or molecular salt formulation. Antioxidant and antibacterial activities (against Gram-positive and Gram-negative bacteria) were also performed in this study. The MP, and FT-IR, were used for the structure elucidation. [ABSTRACT FROM AUTHOR]

We selected 145 reference organic molecules that include model fragments used in computer-aided drug design. We calculated 158 conformational energies and barriers using force fields, with wide applicability in commercial and free softwares and extensive application on the calculation of conformational energies of organic molecules, e.g. the UFF and DREIDING force fields, the Allinger's force fields MM3-96, MM3-00, MM4-8, the MM2-91 clones MMX and MM+, the MMFF94 force field, MM4, ab initio Hartree–Fock (HF) theory with different basis sets, the standard density functional theory B3LYP, the second-order post-HF MP2 theory and the Domain-based Local Pair Natural Orbital Coupled Cluster DLPNO-CCSD(T) theory, with the latter used for accurate reference values. The data set of the organic molecules includes hydrocarbons, haloalkanes, conjugated compounds, and oxygen-, nitrogen-, phosphorus- and sulphur-containing compounds. We reviewed in detail the conformational aspects of these model organic molecules providing the current understanding of the steric and electronic factors that determine the stability of low energy conformers and the literature including previous experimental observations and calculated findings. While progress on the computer hardware allows the calculations of thousands of conformations for later use in drug design projects, this study is an update from previous classical studies that used, as reference values, experimental ones using a variety of methods and different environments. The lowest mean error against the DLPNO-CCSD(T) reference was calculated for MP2 (0.35 kcal mol−1), followed by B3LYP (0.69 kcal mol−1) and the HF theories (0.81–1.0 kcal mol−1). As regards the force fields, the lowest errors were observed for the Allinger's force fields MM3-00 (1.28 kcal mol−1), ΜΜ3-96 (1.40 kcal mol−1) and the Halgren's MMFF94 force field (1.30 kcal mol−1) and then for the MM2-91 clones MMX (1.77 kcal mol−1) and MM+ (2.01 kcal mol−1) and MM4 (2.05 kcal mol−1). The DREIDING (3.63 kcal mol−1) and UFF (3.77 kcal mol−1) force fields have the lowest performance. These model organic molecules we used are often present as fragments in drug-like molecules. The values calculated using DLPNO-CCSD(T) make up a valuable data set for further comparisons and for improved force field parameterization. [ABSTRACT FROM AUTHOR]

The density functionals M06–2X and B3LYP were exploited for investigating the impact of modifying the surface of a boron nitride nano-tube (BNNT) with the furan molecule in terms of energy, electronics, and geometry. According to the density functional theory (DFT) results, BNNT had a strong interaction with the furan molecule. So, the adhesion of the furan molecule onto the surface of BNNT was consistent with the chemical functionalization. Furthermore, the computed density of states indicated that the electronic features of the BNNT were adjusted with a partial chemical modification. Also, the functional energy raised by enhancing the electron donation property of the functional groups, which was due to the rise in the electrical conductance of BNNT in contrast with the pristine BNNT. Retaining the electronic features of BNNT and the increased solubility demonstrated that using furan to chemically modify BNNTs could be a useful method to purify them.

Pressure-induced phases of ZnO have attracted considerable attention owing to their excellent electronic and optical properties. This study provides a vital insight into the electronic structure, optical characteristics, and structural properties of the AsTi (Bi) phase of ZnO under high pressure via the DFT-based first-principles approach. The phase transformation from BN(Bk) to the Bi phase of ZnO is estimated at 16.1 GPa using local density approximation, whereas the properties are explored precisely by the hybrid functional B3LYP. The electronic structure exploration confirms that the Bi phase is an insulator with a wider direct bandgap, which expands by increasing pressure. The dielectric function evidenced that the Bi phase behaves as a dielectric in the visible region and a metallic material at 18 eV. Optical features such as the refractive index and loss function revealed the transparent nature of the Bi phase in the UV range. Moreover, the considered Bi phase is found to possess a high absorption coefficient in the ultraviolet region. This research provides strong theoretical support for the development of Bi-phase ZnO-based optoelectronic and photovoltaic devices. [ABSTRACT FROM AUTHOR]

Five membered hetrocyclic moieties have been proved to possess strong biological activities. The compounds 5-(4-chlorophenyl)-3-(coumarin-3-yl)-1H-pyrazole and 5-(4-chlorophenyl)-3-(coumarin-3-yl)isoxazole were synthesized and characterized by IR, 1H and 13C NMR, and high-resolution mass spectrometry. The structural optimization and the interpretation of theoretical vibrational spectra is made by the Gaussian09 software and the B3LYP/6-31G density functional theory (DFT) approach. Bond lengths, bond angles have all been studied. The Mulliken population analysis on atomic charges is performed. The thermodynamic stability in the ground state and reactivity of the compounds in the excited state are explained by the HOMO–LUMO energy gap. The molecular docking study is carried out using PyRx. The anti-oxidant activities of the derivatives were determined by DPPH scavenging assay. The synthesized compound showed remarkable antioxidant activity. The newly synthesized compounds were tested for their anticancer activity against HeLa cell line in vitro by MTT assay method. [ABSTRACT FROM AUTHOR]

The hybrid correlation method is used to examine the spectra of 5-hydroxy-2-nitrobenzaldehyde (5H2NB) in the FT-IR, FT-Raman, UV, and NMR ranges. For the best molecular shape, vibrational wavenumbers, infrared intensities, and Raman activity using density functional theory, B3LYP and the 6–311++G(2d,p) basis set were used. The MOLVIB software was tasked with providing an in-depth interpretation of the vibrational spectra. Intermolecular charge transfer is a result of bonding orbitals participating as donors and acceptors in all phases of NBO analysis, which stabilizes molecules. High gastrointestinal absorption, but no brain–blood barrier penetration or cytochrome P450 inhibition, was observed despite the expected ADMET characteristics and expected gastrointestinal absorption ((1A2, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4/5). Following CFN and EDE, the results of molecular docking showed that 5H2NB had the highest negative mean binding affinity of –5.818 kcal/mol, followed by CFN and EDE. 5H2NB also had a more significant hydrogen bond with the amino acid residues of selected receptor proteins. As a result, the current compound may be described as a possible analeptic agent. [ABSTRACT FROM AUTHOR]

We studied the C–H activation of ethane on the palladium (Pd) atomic clusters at the CCSD(T)/TZ//B3LYP/DZ level of theory, where TZ and DZ denote the LANL2 valence triple-ζ and double-ζ basis sets that include a relativistic pseudopotential for the Pd core electrons. In this study, we globally optimized first the Pdn clusters (n = 1–8) and then the transition state (TS) structures of Pdn + C2H6 → H−Pdn−C2H5. For each cluster size, we studied four spin states (S = 0, 1, 2, 3). The Pd atom is in the singlet electronic state ([Kr]4d10) at the CCSD(T) level. The CCSD(T) global minima of the Pd3, Pd7, and Pd8 clusters are also in the singlet electronic state, whereas the CCSD(T) global minima of Pd2, Pd4, Pd5, and Pd6 are in the triplet electronic state. The atomization energy of Pdn increases monotonically with the cluster size. Pd4 and Pd6 are particularly stable relative to their neighboring sizes. Among all sizes, Pd4 is the least active toward the C–H bonds in ethane, followed by sizes 5, 7, 3, and 1, whereas Pd2, Pd6, and Pd8 are the most active: the enthalpy of activation of the Pdn + C2H6 → H−Pdn−C2H5 reaction at room temperature are –29, –21, and 8 kJ/mol at these three sizes, respectively, indicating their strong ability to activate ethane. Among these three sizes, Pd2 is highly unstable and thus less ideal. Pd6 and Pd8 are both energetically stable and active toward the C–H bonds of ethane. [ABSTRACT FROM AUTHOR]

Whether tetra‐tert‐butyl‐s‐indacene is a symmetric D2h structure or a bond‐alternating C2h structure remains a standing puzzle. Close agreement between experimental and computed proton chemical shifts based on minima structures optimized at the M06‐2X, ωB97X‐D, and M11 levels confirm a bond‐localized C2h symmetry, which is consistent with the expected strong antiaromaticity of TtB‐s‐indacene. [ABSTRACT FROM AUTHOR]

This study describes the synthesis of 2,5-Bis(3,4-dialkoxy phenyl) Thiazolo[5,4-d} thiazoles (DAITn) (I) and its subsequent structural analysis. These compounds were prepared via reaction of dithio-oxarnidc with the freshly prepared 3,4-dialkoxy benzaldehyde in (DMF). The structure of DAITn (I) was found to have the 3 and 4 positions of the two benzene rings substituted with (OCnH2n+h n=2-5) which equaled to compound M2-M5. The primary methods used for theoretical calculations in this study are quantum mechanics/molecular dynamics simulations based on Density Functional Theory (DFT) and Monte Carlo. The Gaussian09W software's B3LYP hybrid feature and 6-311++G(d,p) basis set were employed in both the gas and aqueous phase for protonated and non-protonated species at the B3LYP level. Electronic structural identifiers were discovered from geometryoptimized structures and correlations between EHOMO (higher occupied molecular orbital energy), ELUMO (lower unoccupied molecular orbital energy), (Eg) bandgap energy, (I) ionization energy, (χ) electronegativity, (ΔN) electron transfer, and (ΔE_(b-d)) back-donation energy were calculated. The Monte Carlo method was used to calculate the adsorption for all identified compounds in this study, and a Fe (110) crystal more stable surface was selected. UV-visible spectroscopy is measuring absorption coefficient, transmittance, and electrical conductivity, and uses a Tauc plot for bandgap energy of the highest absorption peaks. ADTTn molecules with a wide bandgap and a high optical conductivity. Thermodynamic parameters, molecular dynamics simulations, and adsorption energy have been examining inhibitor/surface interactions with greater binding energy leading to stronger interaction and larger negative adsorption energy value indicating a more stable interaction. A four-slab model featuring eighty iron atoms per layer, or one hundred- and ten-unit cells, was used, along with a spline transformation function and a cut-off distance of 1.85 nm for nonbonded interactions. Simulated heating was employed to progressively lower the temperature and search for a low-energy adsorption site. [ABSTRACT FROM AUTHOR]

The metal ion is ubiquitous in the human body and is essential to biochemical reactions. The study of the metal ion complexes and their charge transfer nature will be fruitful for drug design and may be beneficial for the extension of the field. In this regard, investigations into charge transport properties from ligands to metal ion complexes and their stability are crucial in the medical field. In this work, the DFT technique has been applied to analyze the delocalization of electrons from the water ligands to a core metal ion. At the B3LYP level of approximation, natural bond orbital (NBO) analysis was performed for the first five distinct complexes [Mg(H2O)6]2+ and [[Mg(H2O)6](H2O)n]2+; n = 1-4. All these complexes were optimized and examined with the higher basis set 6-311++G(d, p). In the complex [Mg(H2O)6]2+, the amount of natural charge transport from ligands towards the metal ion was 0.179e, and the greatest stabilization energy was observed to be 22.67 kcal/mol. The donation of the p orbitals in the hybrid orbitals was increased while approaching the oxygen atoms of H2O ligands in the 1st coordination sphere with the magnesium ions. The presence of water ligands within the 2nd coordination sphere increased natural charge transfer and decreased the stabilizing energy of the complexes. This may be due to the ligand-metal interactions.

The vibroelectronic parameters of porphyrin and its expanded derivatives termed pyriporphyrin were calculated using density functional theory (DFT). Structures of the reactants (1) and (2) and product (3) were optimized at the B3LYP/6-311G(d,p) level of theory. The time-dependent DFT (TD-DFT) was used to calculate the theoretical UV–visible spectra of 1 and 3. UV–visible spectra of pyriporphyrin shows one broad absorption band at 600–1000 nm (Q-band region), causing a bathochromic shift comparatively two sharp peaks at 300–500 nm (B-band region), which indicates strong evidence for the internal conversion (IC) process. UV–visible studies also supported the distortion in geometry and its antiaromatic behavior. The theoretical IR spectra of 1 and 3 have been calculated using same level of theory. IR spectra calculation indicated the ring expansion of N–H bond all along to N(H)...N(H) path due to the insertion of CH radical on to the β unsaturation forming a novel type of pyriporphyrin compound. Moreover, it causes a significant red shift in frequency at 1539 cm−1 leading in slight distortion at the porphyrinic core from the regular geometry of the porphyrin macrocycle. We have calculated the HOMO–LUMO energy gap corresponding to their pairs of nearly degenerate states, and the nature of electronic excitation was π-π*. The global reactivity parameters confirm the nucleophillic and electrophillic nature of the reactant (1) and for the product (3), respectively. Thermodynamics (ΔH298 and ΔG298) data suggest that the title reaction is highly exothermic and spontaneous in nature. We have explored here a porphyrin ring expansion congener via CH radical cycloaddition-insertion reaction. This theoretical study is expected to support the design of conjugated porphyrin and its derivatives. The result indicates that pyrrolic modification by CH radical was an efficient framework for the longer wavelength absorption. [ABSTRACT FROM AUTHOR]

The geometry optimization of a series of twenty-seven lapachol derivatives used for the treatment of carcinosarcoma tumor (Walker 256) is performed at B3LYP/6–311++G(d,p) level in three distinct media (gas phase, water, and acetonitrile). The migration from the E to the Z configuration or vice versa provokes a noticeable change in the O–H bond distance and potentially a remarkable alteration of the antioxidant activity. In addition, the majority of the E configuration structures have shown a more pronounced antioxidant activity in solution (water and acetonitrile). In their various Z/E configurations, the 2-hydroxy-3-(2,3-dihydroxy-3-methylbutyl)-1,4-naphtoquinone compound bearing O···HO hydrogen bond (La21(HB)) as well as the (2-hydroxy-3-(but-2-enyl)-1,4-naphtoquinone (La6(HB)) and 2-hydroxy-3-(3-methylpent-2-enyl)-1,4-naphtoquinone (La7(HB)) compounds have stronger antioxidant powers than classical bioactive compounds (caffeic acid, ferulic acid, p-coumaric acid, sinapic acid, and vitamin C). On the whole, however, all Z configuration compounds have a higher antiradical status compared to that of their E configuration counterparts. From the global donor–acceptor mappings, the 2-hydroxy-3-(2,3-dihydroxy-3-methylbutyl)-1,4-naphtoquinone structure (La21 (HB)) has been elected as the best antiradical molecule of the series in the three study media. Its antiradical power has been detected to be higher than that of these five standard references adopted. [ABSTRACT FROM AUTHOR]

The use of spintronic devices with a tunable magnetic order on small scales is highly important for novel applications. The MAX phases containing transition metals and/or magnetic ion-substituted lattices attract a lot of attention. In this study, the magnetic and electronic properties of (Cr4-xFex)0.5AC (A = Ge, Si, Al) compounds were predicted and investigated within the density functional theory. It was established that single-substituted (Cr3Fe1)0.5AC (A = Ge, Si, Al) lattices are favorable in terms of energy. An analysis of the magnetic states of the MAX phases demonstrated that their spin order changes upon substitution of iron atoms for chromium ones. It was found that mostly the (Cr4-xFex)0.5GeC and (Cr4-xFex)0.5AlC lattices acquire a ferrimagnetic state in contrast to (Cr4-xFex)0.5SiC for which the ferromagnetic spin order dominates. It was pointed out that the atomic substitution could be an efficient way to tune the magnetic properties of proposed (Cr4-xFex)0.5AC (A = Ge, Si, Al) MAX phases. [ABSTRACT FROM AUTHOR]

In order to study the potential energy surfaces (PESs) of systems containing ethylene, hydrogen, and oxygen atoms, quantum chemical calculations are carried out using the hybrid B3LYP method of the density functional theory (DFT) and the composite CBS-QB3 method. An enthalpy diagram reflecting the PES of this reaction system is constructed. It is shown that the addition of a hydrogen atom to ethylene with the formation of an ethyl radical occurs through the formation of a van der Waals complex. The diagram of enthalpies of monomolecular reactions of decomposition and isomerization of the ethoxyl radical is presented in detail, and a conclusion is made about the probability of their occurrence. The global PES minimum of the system describing the sequential addition of hydrogen and oxygen atoms to ethylene is the hydroxyethyl radical. Intermediates CHCH2OH and CH2OCH2 are localized on the PES of the C2H4 + O system and possible pathways for their further transformation are analyzed. The data obtained make it possible to estimate the ranking of individual elementary reactions in the processes of combustion and oxidation of hydrocarbons and the probabilities of various directions for the transformation of chemical species in the studied systems. [ABSTRACT FROM AUTHOR]

This paper reports the energies and charge and spin distributions of the mono-substituted N defects, N0s, N+s, N−s and Ns-H in diamonds from direct Δ-SCF calculations based on Gaussian orbitals within the B3LYP function. These predict that (i) Ns0, Ns+ and Ns− all absorb in the region of the strong optical absorption at 270 nm (4.59 eV) reported by Khan et al., with the individual contributions dependent on the experimental conditions; (ii) Ns-H, or some other impurity, is responsible for the weak optical peak at 360 nm (3.44 eV); and that Ns+ is the source of the 520 nm (2.38 eV) absorption. All excitations below the absorption edge of the diamond host are predicted to be excitonic, with substantial re-distributions of charge and spin. The present calculations support the suggestion by Jones et al. that Ns+ contributes to, and in the absence of Ns0 is responsible for, the 4.59 eV optical absorption in N-doped diamonds. The semi-conductivity of the N-doped diamond is predicted to rise from a spin-flip thermal excitation of a CN hybrid orbital of the donor band resulting from multiple in-elastic phonon scattering. Calculations of the self-trapped exciton in the vicinity of Ns0 indicate that it is essentially a local defect consisting of an N and four nn C atoms, and that beyond these the host lattice is essential a pristine diamond as predicted by Ferrari et al. from the calculated EPR hyperfine constants. [ABSTRACT FROM AUTHOR]

The occupancy of the d shell in KFeF 3 is t 2 g 4 e g 2 , with five α and one β electrons. The Jahn–Teller lift of degeneracy in the t 2 g sub-shell produces a tetragonal relaxation of the unit cell (4.09 vs. 4.22 Å, B3LYP result) not observed experimentally. In order to understand the origin of this apparent contradiction, we explored, with a 2 × 2 × 2 supercell (40 atoms per cell), all possible local structures in which contiguous Fe atoms have a different occupancy of the t 2 g orbitals with the minority spin electron. A total of 6561 configurations (with occupancies from (8,0,0) to (3,2,2) of the 3 t 2 g orbitals of the 8 Fe atoms) have been explored, with energies in many cases lower (by up to 1550 μ E h per 2 Fe atoms) than the one of the fully ordered case, both for the ferromagnetic and the anti-ferromagnetic solutions. The results confirm that the orientation of the β d electron of Fe influences the electrostatics (more efficient relative orientation of the Fe quadrupoles of the d shell) of the system, but not the magnetic interactions. Three hybrid functionals, B3LYP, PBE0, and HSE06, provide very similar results. [ABSTRACT FROM AUTHOR]

Ca2+-triggered coelenterazine-binding protein (CBP) is a natural form of the luciferase substrate involved in the Renilla bioluminescence reaction. It is a stable complex of coelenterazine and apoprotein that, unlike coelenterazine, is soluble and stable in an aquatic environment and yields a significantly higher bioluminescent signal. This makes CBP a convenient substrate for luciferase-based in vitro assay. In search of a similar substrate form for the luciferase NanoLuc, a furimazine-apoCBP complex was prepared and verified against furimazine, coelenterazine, and CBP. Furimazine-apoCBP is relatively stable in solution and in a frozen or lyophilized state, but as distinct from CBP, its bioluminescence reaction with NanoLuc is independent of Ca2+. NanoLuc turned out to utilize all the four substrates under consideration. The pairs of CBP-NanoLuc and coelenterazine-NanoLuc generate bioluminescence with close efficiency. As for furimazine-apoCBP-NanoLuc pair, the efficiency with which it generates bioluminescence is almost twice lower than that of the furimazine-NanoLuc. The integral signal of the CBP-NanoLuc pair is only 22% lower than that of furimazine-NanoLuc. Thus, along with furimazine as the most effective NanoLuc substrate, CBP can also be recommended as a substrate for in vitro analytical application in view of its water solubility, stability, and Ca2+-triggering "character". [ABSTRACT FROM AUTHOR]

The process of midazolam ring closure was studied from the thermodynamic and kinetic points of view by means of quantum-chemical methods. B3LYP/6–311 + + G(d,p) model was employed for gas phase and water environment (polarizable continuum model) calculations. It was concluded that the reaction rate determining step is the first step—carbinolamine formation from amine and carbonyl ends of the opened benzodiazepine ring. The Gibbs free energy of activation was calculated as 35.1 kcal/mol for gas- phase and 33.9 kcal/mol for water environment. Intrinsic reaction coordinate calculations were performed to verify that the transition state really connects the substrate and product. Thermodynamically, this reaction is endoergic with ΔG = 9.6 kcal/mol for gas phase and 10.0 kcal/mol for water environment. However, the next step—carbinolamine protonation with immediate water molecule loss is expected to be fast and activation barrierless, which enables further progress of the ring closure, despite the positive ΔG of the fist step. Next, the protonated imine undergoes deprotonation to final closed ring, pharmacologically active molecule of midazolam. The whole chain of reaction is exoergic with ΔG equal to − 5.6 kcal/mol for gas phase and − 7.7 kcal/mol for water environment. In order to understand the role of other than benzodiazepine/imidazole molecular fragments on the ring closure process, a model was build which contains only benzodiazepine and imidazole rings. The activation barrier for the carbinolamine formation of the model is similar to midazolam in the gas phase but higher by about 10 kcal/mol for water environment. The most interesting difference is however that for the model, the carbinolamine formation step is exoergic with ΔG equal to − 2.2 kcal/mol for gas phase and − 1.8 kcal/mol for water environment. This difference can be connected to complicated conformational shape of the midazolam molecule, which during the ring closure undergoes unfavorable deformations with accompanying rise of the energy of the molecule. The protonation sites for both midazolam and the model were also studied. In the case of midazolam, the preferred protonation site is the imidazole ring nitrogen atom, but in the case of the model it is the benzodiazepine ring nitrogen atom. The aromaticity of the 5- and 7-membered rings were analyzed using two aromaticity—HOMA and pEDA. It follows that larger stability of the cation protonated at the benzodiazepine ring is accompanied with substantial increase of the 7-ring aromaticity in the model of midazolam. The complexes of midazolam and its model with a water molecule were analyzed because they are needed for evaluation of the energy of the whole process of ring closure. In the case of midazolam, the water molecule preferentially connects to imidazole ring, but in the case of the model, complexes with both imidazole and benzodiazepine rings have similar stability. [ABSTRACT FROM AUTHOR]

This work summarizes the theoretical study of the addition reaction of 4- methylbenzoyl chloride on 4-hydroxycoumarin. Indeed, it is a question of studying thermodynamically the acylation reaction of 4-hydroxycoumarin, of carrying out the synthesis experimentally and then of characterizing the products obtained. Based on the « density functional theory » DFT calculation method with the basic standard 6–31G** and the B3LYP functionalities, we have discussed, from the thermodynamic and orbital point of view, the possibility of reactions. The theoretical results obtained are satisfactory. We therefore proceeded to the synthesis of 3-(4-methylbenzoyl)-4-hydroxycoumarin (d) in two steps via a reaction intermediate, coumarin-3-yl 4-methylbenzoate (c). The structures of the product as well as the isolated intermediate were described using the following spectral methods: infrared, 13 C and 1H nuclear magnetic resonance, and mass spectrometry [ABSTRACT FROM AUTHOR]

Introduction: Alzheimer's disease is a form of dementia which affects majority of the people. It is characterized by memory loss and other cognitive function disabilities and is one of the most challenging neurodegenerative disorders to treat because of its progressive nature. The disease affects millions of people all around the world, and the number of those affected is expanding every day. In the previous study, the 4-phthalimidobenzenesulfonamide derivatives were synthesized as AChE and BChE inhibitors, and here, we were aiming to further reporting in silico studies of these compounds for efficient drug discovery process and to find out the potential lead compounds. Methods: In silico characterization included density functional theory (DFT) studies, 3D-QSAR, ADMET properties, molecular docking, and molecular dynamic simulations. The geometries of all derivatives were optimized using B3LYP method and 6-311G basis set. Results: The findings of the current study revealed that 4-phthalimidobenzenesulfonamide derivatives exhibited a reactive electronic property which is essential for anticholinesterase activity. Moreover, optimized structures were subjected to molecular docking studies with targeted protein. The compounds 2c and 2g showed excellent binding score of −37.44 and −33.67 kJ/mol with BChE and AChE, respectively, and exhibited strong binding affinity. The potent derivatives produced stable complex with amino acid residues of active pocket of both BChE and AChE. The stability of protein-ligand complexes was determined by molecular dynamic simulation studies, and results were found in correlation with molecular docking findings. Conclusion: Findings of the current study suggested that these derivatives are potent inhibitors of cholinesterase enzyme. [ABSTRACT FROM AUTHOR]

Herein, a screen–printed diamond electrode (SPDE) coupled with a "point-of-care" platform (30 µL-drop concepts, single-drop-detection approach) was successfully applied for the electrochemical determination of pterostilbene (PTS). Cyclic voltammetry identified irreversible oxidation of PTS, where oxidation peak was shown to be strongly dependent on the pH of the working environmental. Although the proposition of the detailed electrochemical oxidation mechanism of PTS goes out of the scope of the present research, we have determined the most probable reactive site of our analyte, by utilizing DFT-based reactivity descriptors (Fukui functions). For electrochemical quantification of PTS, oxidation peak at 0.32 V (vs. Ag/AgCl) was followed in presence of 0.5 mol L−1 of Briton–Robinson buffer solution (pH = 9). Coupled with the optimized parameters of differential pulse voltammetry (DPV), SPDE detected PTS in two linear ranges (first range was from 0.011 to 0.912 µmol L−1; second range was from 0.912 to 4.420 µmol L−1), providing the LOD and LOQ on a nanomolar level (3.1 nmol L−1 and 10.0 nmol L−1, respectively). The selectivity of the optimized DPV method was found to be excellent, with the current changes of less than 7%, in the presence of ten times higher concentrations of the certain interferences. The practical applicability of the SPDE and single-drop-detection approach in dietary supplements (with a declared PTS content of 50 mg/tablet), with the recovery values ranging from 95 to 102%, shows that the developed method has high potential for precise and accurate PTS detection, as well as exceptional miniaturization possibilities of relevant equipment for on-site sensing. [ABSTRACT FROM AUTHOR]

This study applies Density Functional Theory (DFT), using the B3LYP functional, and via ab initio Restrict Hartree-Fock (RHF) methods, to study the infrared spectrum of steroid 17-Iodo-androst-16-ene. The spectrum was obtained via computational methods ab initio RHF and DFT. Optimization of molecular structure via UFF (Universal Force Field), followed by PM3 (Parametric Method 3), with geometric optimization, obtaining the spectrum of other basis sets of steroid 17-Iodo-androst-16-ene. The study this steroid was chosen because it can could act as aromatase enzyme inhibitors and this phenomenon could be translated as good compounds to treat breast cancer. The B3LYP functional always presents the lowest thermal energy than the RHF in all calculated bases, however the RHF always presents the highest Entropy than the B3LYP, in all the calculated basis sets. The normalized spectrum calculated in the B3LYP/SVP functional/basis set have harmonic frequency with peaks 3,241.83 cm-1, 100% and 3,177.53.5 cm-1 at 43.304% absorbance. The study has so far been limited to computational methods compatible with the theory of quantum chemistry. [ABSTRACT FROM AUTHOR]

Compound synthesized N-[4-((2R)-octan-2-yloxy)benzyl]-N,N-dimethyl-hexadecane-1-aminium tosylate, which is a promising candidate for use in liquid crystal compositions. The Raman spectrum of the synthesized sample was also recorded. The equilibrium configuration of the molecule (ion) was calculated by optimization for all geometric parameters at the level of the B3LYP/cc-pVTZ theory. In addition, the equilibrium configurations of three more stable conformers of the molecule were calculated. The relative energies of the four conformers, their dipole moments were determined, and their IR and Raman spectra were calculated. Comparison of the calculated and experimental vibrational spectra of the molecule made it possible to assign the absorption bands and Raman scattering lines to the vibrations of molecular fragments. [ABSTRACT FROM AUTHOR]