Average Local Ionization Energy Research Articles

Three-Dimensional Quantitative Structure and Activity Relationship of Flavones on Their Hypochlorite Scavenging Capacity.

Flavonoids, a class of polyphenolic substances widely present in the plant realm, are considered as ideal hypochlorite scavengers. However, to our knowledge, little study has focused on the structure-activity relationship between flavonoids and hypochlorite scavenging capacity. Herein, we report for the first time the three-dimensional quantitative structure and activity relationship (3D-QSAR) combined with comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). Four models derived from CoMFA and CoMSIA with different combinations of descriptors were built and compared; the CoMFA model, which included both steric and electrostatic fields, showed great potential (R2 = 0.989; Q2 = 0.818) in predictive quality according to both internal and external validation criteria. Additionally, the average local ionization energy (ALIE), electrostatic potential (ESP), and orbital weighted dual descriptor (OWDD) were determined to identify the key structural moiety for scavenging capacity of flavonoids against hypochlorite. The computational results indicated that hypochlorous acid (HClO) serves as an electrophile undergoing electrophilic addition to the C6 carbon, which has the highest negative charge density, which are influenced by the functional groups on the flavones. The DFT calculated mechanism revealed the catalytic role of water of mono- and di-chlorination reactions, characterized by low activation barriers, and the involvement of neutral, instead of high-energy carbocation, intermediates.

Investigations on mechanisms, kinetics, and ecotoxicity in OH-initiated degradation of 1,2,4,5-tetramethylbenzene in the environment.

As one of the volatile organic compounds (VOCs) in the environment, 1,2,4,5-tetramethylbenzene (1,2,4,5-TeMB) present in oily wastewater, and it can occur substitution, abstraction, and addition reactions with OH radicals in theatmosphere and wastewater. Electrostatic potential (ESP) and average local ionization energy (ALIE) prediction indicate that H atoms from CH3 group and the benzene ring are the most active sites in 1,2,4,5-TeMB. The result shows that potential energy surfaces (PESs) in the gas and aqueous phase are similar, and the relevant barriers in the latter one are higher. The dominant channel is H abstraction from the benzene ring, and the subdominant one is OH radical addition to the benzene ring. Furthermore, subsequent reactions of dominant products with O2, NO2, NO, and OH radicals in the atmosphere are studied, as well. The total reaction rate constant is calculated to be 2.36×10-10 cm3 molecule-1 s-1 at 1 atm and 298 K in the atmosphere, which agrees well with the experimental data. While the total rate constant in the aqueous phase is much lower than that in the gas phase. Ecologic toxicity analysis shows that 1,2,4,5-TeMB is very toxic to fish, daphnia, and green algae; and OH-initiated degradation in the environment will reduce its toxicity.

Quantitative surface and Hirshfeld surface analysis of nicorandil molecule and further insight into its solubility in several aqueous protic and aprotic cosolvent solutions

The quantum-chemical quantities of highest negative surface electrostatic potential and lowest surface average local ionization energy as well as Hirshfeld surface were used herein to explain the electrostatic features of both basicity and acidity of nicorandil molecule. The primary electrophilic and nucleophilic sites are the -Nand > NH groups, respectively. According to the nicorandil solubility in solutions of isopropanol (1) + water (2), ethanol (1) + water (2), DMF (1) + water (2), and methanol (1) + water (2), preferential solvation of nicorandil was investigated using the famous inverse Kirkwood-Buff integrals approach. In poor water composition areas, nicorandil was surrounded preferentially by organic solvent, showing the selective solvation of nicorandil by methanol/DMF/ethanol/isopropanol. This performance was due to high basicity of organic solvents compared with water, which favors interactions with nicorandil's acidic groups. The Hansen solubility parameter was used to evaluate the performance of nicorandil solubility in depth. The derived dissolution Gibbs energy change, enthalpy and entropy indicated that the solubilization capacity improved with increasing methanol/DMF/ethanol/isopropanol compositions. As the proportions of methanol/DMF/ethanol/isopropanol rose, analysis of enthalpy–entropy compensation revealed a shift in main dissolving mechanism from enthalpy-driven to entropy-driven (alcohol solutions) or from entropy-driven to enthalpy-driven (DMF solutions).

Electron-Induced Decomposition of Different Silver(I) Complexes: Implications for the Design of Precursors for Focused Electron Beam Induced Deposition.

Focused electron beam induced deposition (FEBID) is a versatile tool to produce nanostructures through electron-induced decomposition of metal-containing precursor molecules. However, the metal content of the resulting materials is often low. Using different Ag(I) complexes, this study shows that the precursor performance depends critically on the molecular structure. This includes Ag(I) 2,2-dimethylbutanoate, which yields high Ag contents in FEBID, as well as similar aliphatic Ag(I) carboxylates, aromatic Ag(I) benzoate, and the acetylide Ag(I) 3,3-dimethylbutynyl. The compounds were sublimated on inert surfaces and their electron-induced decomposition was monitored by electron-stimulated desorption (ESD) experiments in ultrahigh vacuum and by reflection−absorption infrared spectroscopy (RAIRS). The results reveal that Ag(I) carboxylates with aliphatic side chains are particularly favourable for FEBID. Following electron impact ionization, they fragment by loss of volatile CO2. The remaining alkyl radical converts to a stable and equally volatile alkene. The lower decomposition efficiency of Ag(I) benzoate and Ag(I) 3,3-dimethylbutynyl is explained by calculated average local ionization energies (ALIE) which reveal that ionization from the unsaturated carbon units competes with ionization from the coordinate bond to Ag. This can stabilise the ionized complex with respect to fragmentation. This insight provides guidance with respect to the design of novel FEBID precursors.

Mechanisms and Kinetics Studies of Butylated Hydroxytoluene Degradation to Isobutene.

2,6-Di-tert-butyl-hydroxytotulene (BHT) is a widely used antioxidant in various fields. In this study, we explored comprehensively the mechanisms and kinetics of BHT degradation to produce isobutene using the density functional theory method. Furthermore, the intrinsic chemical reactivity of BHT was investigated using the electrostatic potential, average local ionization energy, and Fukui function, and the most likely reaction site with OH radical was predicted. Two initiation pathways of BHT with OH radicals were reported. The OH addition pathways at the C2 site of BHT was found more likely to occur than the pathways of H abstracts from the t-butyl group due to the lower energy barrier. Rate constants of two initiation pathways were calculated by transition state theory, and they were promoted by the temperature rise. Mayer bond order and localized molecular orbitals analysis were conducted to reveal the variation of the chemical bonds in the reaction process. The tertiary butyl radical that had been generated in the OH-addition reaction was more likely to generate isobutene with the participation of oxygen. Overall, this research could help to reveal the transformation mechanism of isobutene produced by BHT degradation.

Synthesis and application of poly methyl indole-4-carboxylate with blue light blocking properties

Blue light hazards have garnered increasing attention owing to the popularity of displays. Although melanin on the retina acts as a blue light barrier, overexposure to blue light increases the risk of visual damage. A class of methyl indole-n-carboxylate oligomers (O-MInC, n = 3, 4, 5, 6, and 7) was synthesized through solid-phase oxidative polymerization. Based on the experimental characterizations, including time-of-flight mass spectrometry, infrared spectroscopy, and density functional theory calculations of the average local ionization energy, we proposed a mechanism for the oxidative polymerization of methyl indole-4-carboxylate (MI4C). Methyl indole-4-carboxylate oligomer (O-MI4C) is composed of cyclic oligomers containing large conjugated structures that are generated by the repetition of electron deprivation, radical coupling, and dehydrogenation reactions. O-MI4C exhibits the best blue light absorption among its allotropes substituted at different positions with a cut-off absorption wavelength of 530 nm. Finally, O-MI4C was added to polymethylmethacrylate (PMMA) and Columbia resin 39 (CR-39) flakes through in situ polymerization to investigate the behavior of blue light blocking. The PMMA/O-MI4C (0.01 wt%) and CR-39/O-MI4C (0.02 wt%) can block 25% and 35% of blue light; however, they have no significant effect on green and orange lights.

Quantitative molecular surface analysis of doxofylline and its thermodynamic solubility behavior in aqueous solutions

The Hirshfeld surface, molecular surface electrostatic potential together with molecular surface average local ionization energy, were employed in this work to analyze the electrostatic characteristics of acidity and basicity of doxofylline at a microscopic level. H···H and O···H contacts present predomination among all contact interactions and doxofylline molecule can behave as a hydrogen-bonding donor with powerful ability. The nitrogen of -N = group and oxygen of >C=O group of doxofylline molecule are primary sites of electrophilic attack. The mole-fraction solubility of doxofylline in four blends of isopropanol + water, ethanol + water, acetone + water and methanol + water covering the temperature from 278.15 to 323.15 K was acquired by the use of saturation shake-flask method under atmospheric pressure of 101.2 kPa. For each aqueous solution, the solubility data firstly presented a peak at isopropanol (ethanol, acetone or methanol) composition of 0.7 and then decreased with the increasing mass fraction of organic solvents at a fixed temperature. No existence of crystaltransition and solvation was recorded in all experiments as indicated by X-ray power diffraction patterns. Solubility data were mathematically correlated by Jouyban-Acree, modified Wilson model, Apelblat and modified van’t Hoff-Jouyban–Acree models. Investigation on preferential solvation of crystalline doxofylline was performed by the inverse Kirkwood–Buff integrals over temperatures from 293.15 to 313.15 K. The preferential solvation parameters of isopropanol, acetone or acetonitrile presented positive values in blends with middle isopropanol/acetone/acetonitrile composition regions, demonstrating the preferential solvation of doxofylline by isopropanol/acetone/acetonitrile. In addition, the extended Hildebrand solubility approach was employed to quantitatively describe the solubility behavior at 298.15 K in isopropanol/ethanol/acetone/methanol + water blends studied in this paper and in acetonitrile + water blends previously reported, attaining the average relative deviations of < 7.80 %.

Quantitative surface analysis of paclobutrazol molecule and comprehensive insight into its solubility in aqueous co-solvent solutions

As powerful tools, the minimum negative surface electrostatic potential together with minimum surface average local ionization energy, were used herein to illustrate the electrostatic characteristics of acidity and basicity at a microscopic level, correspondingly. The groups of -N = and –OH of the paclobutrazol molecule are primary sites of electrophilic and nucleophilic attack. The mole-fraction solubility of paclobutrazol in three co-solvent blends of isopropanol + water, acetone + water and acetonitrile + water covering the temperature range from 278.15 to 318.15 K was experimentally acquired by the use of isothermal saturation method under 101.2 kPa. Under the identical experimental conditions, e.g. same temperature and mass composition of isopropanol (acetone or acetonitrile), the solubility of paclobutrazol in mole fraction was much larger in acetone + water blends than in isopropanol/acetonitrile + water blends. The minimal solubility was recorded in neat water solvent at 278.15 K; and the maximal one, in acetone/acetonitrile/isopropanol at T = 318.15 K. No appearance of crystaltransition as well as solvate formation was observed in experiments as indicated by X-ray power diffraction patterns. Solubility data were mathematically correlated by three models including Jouyban-Acree, Apelblat and modified van’t Hoff-Jouyban–Acree. Investigation on preferential solvation of crystalline paclobutrazol was performed by the powerful approach of inverse Kirkwood–Buff integrals at 298.15 K. The preferential solvation parameters of isopropanol, acetone or acetonitrile presented positive values in blends with middle and isopropanol/acetone/acetonitrile-rich composition regions, which indicated the preferential solvation of paclobutrazol by the co-solvents. In addition, the extended Hildebrand solubility approach was employed to quantitatively describe the solubility behavior at 298.15 K in isopropanol/acetone/acetonitrile + water blends studied in this paper and in ethanol/n-propanol/1,4-dioxane + water blends previously reported by us, attaining the average relative deviations < 7.61 %.

Equilibrium solubility of amrinone in aqueous co-solvent solutions reconsidered: Quantitative molecular surface, inter/intra-molecular interactions and solvation thermodynamics analysis

Two powerful tools of quantum-chemical parameters, minimum negative surface electrostatic potential together with minimum surface average local ionization energy, were employed in this communication to illustrate the electrostatic characteristics of acidity and basicity from a microscopic point of view, correspondingly. The -N = and > NH groups of amrinone molecule are primary sites of electrophilic and nucleophilic attacks. With the help of the famous method of inverse Kirkwood–Buff integrals, preferential solvation analysis was executed based on the reported amrinone solubility in four solution systems of EG (1) + water (2), ethanol (1) + water (2), DMF (1) + water (2) and methanol (1) + water (2). In rich water concentrations, amrinone was surrounded preferentially by water; while in intermediate and rich EG/ethanol/DMF/methanol compositions, EG/ethanol/DMF/methanol solvated preferentially amrinone. High basicity of EG/ethanol/DMF/methanol that favored interactions with the acidic groups of amrinone resulted in selective solvation of amrinone by the co-solvent. Deep investigation on the amrinone solubility behavior was done by the partial Hansen solubility parameters. The inspection of molecular interactions on amrinone solubility variation was made in the light of the well-known linear solvation energy relationships, identifying the solubility parameter, hydrogen-bond acidity and dipolarity-polarizability of solutions presented dominant contributions to the solubility variation. The transfer and thermodynamic dissolution properties including entropy, enthalpy and Gibbs free energy change were also derived and deeply discussed. Thermodynamic enthalpy–entropy compensation analysis validated a shift of prevailing mechanism of dissolution from entropy-driven (in rich water compositions) to enthalpy-driven (in rich co-solvent compositions).

Structure analysis and insight into hydrogen bond and van der waals interactions of etoricoxib cocrystals and cocrystal solvate

Etoricoxib (ETR) is a non-ionizable BCS class II drug with no typical hydrogen bond donors and low solubility in water. Cocrystal was proved to be a good strategy to improve bioavailability. In this work, the excess enthalpy (△Hex) was used to shorten the time of the screening of ETR cocrystals. Six cocrystals of ETR and one cocrystal solvate have been synthesized and characterized. The dissolution experiments showed that all cocrystals performed a higher apparent solubility compared with ETR Form Ⅴ. To gain insight into the intermolecular interactions of cocrystals, the crystal structures have been solved by single crystal X-ray diffraction and other analysis methods. The average local ionization energy (ALIE) analysis shows that pyridine nitrogen is more susceptible to be attacked by the electrophiles than sulfonyl oxygen. Therefore, O-H···N rather than O-H···O hydrogen bond dominates the formation of supramolecular synthons. Van der Waals (vdW) force is another main driving force that works together with hydrogen bonds to form basic units of ETR-CT cocrystal and ETR-HQ-MeOH cocrystal solvate. The hydrogen bond strength of all the ETR cocrystals and cocrystal solvate was calculated by atoms-in-molecules theory, which was rationalized by natural population analysis. Overall, our work presents the structure analysis of six newly formed ETR cocrystals and one cocrystal solvate, which provides a deeper insight into intermolecular interactions of cocrystals at the molecular level.

Rational modulation of N and O binding in Fe(III) complex formation derived from hydroxychloroquine: Synthesis, spectroscopic, computational, and docking simulation with human thrombin plasma

Hydroxychloroquine (HCQ) can bind with Fe(III) by both N and O atoms to form either [Fe-HCQ] or [Fe-(HCQ)2] complex. The characterization of the product developed as a result of the reaction between HCQ and Fe(III) salt suggested the formation of [Fe-HCQ] complex. Rational studies characterized the synthesized complex with several types of spectroscopic analysis such FT-IR, UV-Visible and mass spectra and XRD evaluation. The computational analysis involved in this study view an investigation about the electronic behavior around the central metal atom coordinated to the donor ligand atoms. The postulation discussed the formation of [Fe-HCQ] complex rather than [Fe-(HCQ)2] complex. Quantum reactivity parameters (Physiochemical properties) and FMOs analysis were studied. Important topological parameters such as electronic localization function (ElF), average local ionization energy (ALIE), and molecular electrostatic potential (MEP) analyses were studied; also, non-covalent interaction- reduced density gradient (NCI-RDG) analysis illustrated the type of interactions in HCQ and [Fe-HCQ]. Molecular docking of the ligand and its synthesized complex was performed on the protein crystal structure (5TO3) of human thrombin plasma, and a good predicted result was obtained in inhibiting thrombosis acceleration with the synthesized Fe-complex. Molecular dynamic simulation analysis was applied to predict the stability of the studied compounds based on energetic variables and RMSD values.

Simulation of Gas Production Mechanisms in Shear Deformation of Medium-Rank Coal.

The discovery of mechanochemical action provides a theoretical basis for revealing gas production from coal under stress degradation. The research on gas production in such a manner is conducive to revealing mechanisms of coal and gas outburst and excess coalbed methane (CBM). By selecting a model of a macromolecular structure of Given medium-rank coal, its structure was optimized based on molecular mechanics, molecular dynamics, and quantum chemistry, and the six optimized models were constructed into a coal polymer cell. The coal polymer cell was loaded to shear deformation through large-scale atomic/molecular massively parallel simulator (LAMMPS) software. The Given model was optimized by quantum chemistry software Gaussian and the frequency was calculated to obtain the bond strength and average local ionization energy (ALIE). The following understanding was reached: under shear, bridge bonds of a ring structure, and large π-bonds are subjected to shear and tensile action, and atoms (atomic clusters) in the outermost region of coal macromolecules tend to be sheared by surrounding molecules. The shear action shortens a molecular chain of medium-rank coal with a cross-linked structure and promotes the evolution of the coal macromolecular structure. The shear action can lead to the formation of free radicals, such as H• and •CO from macromolecules of medium-rank coal, thus producing many small gas molecules, such as H2 and CO. Moreover, the shear action can not only break chemical bonds but also can produce new chemical bonds. The research on gas production mechanisms under shear deformation of medium-rank coal provides a certain reference for studying mechanochemistry.

Analysis of the combustion mechanism of diesel surrogate fuel under CO2/O2 atmosphere

Closed-cycle diesel engine (CCDE) can effectively control CO2 emissions and reduce the greenhouse gas effect, but diesel fuel combustion under an atmosphere with CO2 has the problem of misfire and unclear mechanism. In order to study the CO2 impact on diesel combustion under the CO2/O2 atmosphere, a quantum chemical (QC) model of diesel surrogate fuel (DSF) is proposed, which takes into account the CO2 pyrolysis effect (CO2⇆CO+12O2) and the new reaction of OH radical generation from pyrolysis products (CO+O2+H∙→CO2+OH∙). Firstly, the active sites of the DSF molecules are predicted by average local ionization energy (ALIE) and electrostatic potential (ESP). New chemical reaction paths are obtained using ab initio theory and density functional theory combined with thermodynamic combination algorithm. The QC model is then established by sensitivity analysis and simplification of the mechanism and computational fluid dynamics (CFD) simulation of constant volume combustion chamber (CVCC.) Secondly, the CVCC experiment bench and visualization system are set up. The flame propagation at different times (1.5 ms, 1.9 ms, 2.3 ms, 2.7 ms, 3.1 ms and 3.5 ms) are captured by high-speed cameras under four different CO2 concentrations (air condition, 50%CO2 + 50%O2, 43%CO2 + 57%O2 and 35%CO2 + 65%O2). Finally, the comparison between experiment and model shows that the QC model is suitable for studying combustion characteristics of diesel fuel under CO2/O2 atmosphere. Under maximum CO2 concentration (50%CO2 + 50%O2), The maximum errors of flame combustion limit length (FCLL) and Flame longitudinal section area (FLSA) are 8.54% and 4.94%, respectively. In addition, the CO2 pyrolysis reaction and the new reaction of generating OH radicals indicate that the CO2 chemical effect can promote the combustion of diesel fuel under CO2/O2 atmosphere.

Detailed Study of Three Halogenated Benzylpyrazole Acetamide Compounds with Potential Anticancer Properties

Spectroscopic and chemical properties of three acetamide derivatives are investigated experimentally and theoretically. Detailed functional group assignment shows that the important functional mode frequencies are in agreement with the simulated values. The nitrogen atom in the acetamide group has very strong hyper conjugative interactions with the neighboring groups. Studies of frontier orbitals showed that the LUMO is delocalized in mono substituted phenyl rings of all systems while the HOMO is over the pyrazole ring and acetamide group with changes in polarity. Electron localization function showed that electrons are more localized in the C–H bond adjacent to C–Cl bonds in the aromatic ring. Average local ionization energy in the molecule surface has also been reported. The compounds might exhibit inhibitory activity against antitumor protein-chromophore complexes.

Investigation of Pharmaceutical Importance of 2H-Pyran-2-One Analogues via Computational Approaches

Highly functionalized spirocyclic ketals were synthesized through asymmetric oxidative spirocyclization via carbanion-induced ring transformation of 2H-pyran-2-ones with 1,4-cyclohexandione monoethyleneketal under alkaline conditions. Further acidic-hydrolysis of obtained spirocyclic ketals yields highly substituted 2-tetralone in good yield. Computational analysis based on the DFT calculations and MD simulations has been performed in order to predict and understand global and local reactivity properties of newly synthesized derivatives. DFT calculations covered fundamental reactivity descriptors such as molecular electrostatic potential and average local ionization energies. Nitrogen atom and benzene rings have been recognized as the most important molecular sites from these aspects. Additionally, to predict whether studied compounds are stable towards the autoxidation mechanism, we have also studied the bond dissociation energies for hydrogen abstraction and identified the derivative which might form potentially genotoxic impurities. Interactions with water, including both global and local aspects, have been covered thanks to the MD simulations and calculations of interaction energies with water, counting of formed hydrogen interactions, and radial distribution functions. MD simulations were also used to identify which excipient could be used together with these compounds, and it has been established that the polyvinylpyrrolidone polymer could be highly compatible with these compounds, from the aspect of calculated solubility parameters.

A novel sulfamethoxazole derivative as an inhibitory agent against HSP70: A combination of computational with in vitro studies

In the current study, a novel derivative of sulfamethoxazole (a sulfonamide containing anti-biotic) named ZM-093 (IUPAC name: (E)-4-((4-(bis(2-hydroxyethyl)amino)phenyl)diazenyl)-N-(5-methylisoxazole-3-yl)benzenesulfonamide) was synthesized via common diazotization-coupling reactions from sulfamethoxazole and subsequently characterized through NMR/FT-IR spectroscopy. After evaluation, the compound was geometrically optimized at the DFT level of theory with BL3YP method and 6/31++G (d,p) basis set and from the optimized structure, several molecular descriptors important in the biological reactivity of the compound, such as global reactivity parameters, molecular electrostatic potential, average local ionization energy, and drug-likeness features of the compound were computationally analyzed. The experimental in vitro investigations of the interaction between ZM-093 and heat shock protein 70 (HSP70), a protein that is highly expressed in several types of cancers, exhibited a significant inhibitory effect against the chaperone activity of HSP70 for the titled compound (P-value < 0.01) and the comparison between the experimental studies with the mentioned computational analysis, as well as molecular docking, illustrated that ZM-093 may inhibit HSP70 through binding to its substrate-binding domain. Finally, by taking all the previous results into account, a new method for assessing the inhibitory activity of ligand to HSP70 is introduced based on protonography, a recently developed method that is dependent on the catalytic activity of carbonic anhydrase on polyacrylamide gel electrophoresis.

Vibrational Spectral Studies, Quantum Mechanical Properties, and Biological Activity Prediction and Inclusion Molecular Self-Assembly Formation of N-N’-Dimethylethylene Urea

A cyclic urea analog, N-N'-dimethylethylene urea, was studied using different spectral methods like FT-IR, FT-Raman, and UV-VIS methods followed by computational simulations. The experimental and simulated spectra are compared, and a detailed assignment of vibrations and potential energy distribution is made. It was followed by various quantum mechanical studies like frontier orbital analysis, energy descriptors, average local ionization energies, and nonlinear optical properties. The NBO gave an insight into the various intramolecular stabilizing electron delocalization by hyperconjugation. Noncovalent interaction analysis provided various types of interactions present in the molecule. We also studied ALIE, local information entropy, electron localized function, reduced density gradient studies, localized orbital locator studies, and other analyses. Molecular docking results indicated that this urea derivative acted as an ATP-hydrolysing inhibitor, and the drug delivery ability of cyclodextrin on NND was tested by forming an inclusion complex with both compounds with dispersion and without dispersion interaction.

Detailed Structural Examination, Quantum Mechanical Studies of the Aromatic Compound Solarimfetol and Formation of Inclusion Compound with Cucurbituril

This manuscript aims to look at the structure and the other physical and chemical properties of solriamfetol, which is used to treat excessive sleepiness, using electronic structure methods. Density functional theory optimizes the ground state geometries of the molecules, and the frontier molecular orbitals are analyzed using B3LYP functional and 6-311++G (2d,p) basis sets. They give ample information regarding the electronic properties and descriptors, which can be used to predict the same molecule's biological activity. Evaluation of aromaticity has been performed using the nuclear induced chemical shift (NICS) measurements. Electrostatic potential, average local ionization energy and the assessment of non-covalent interactions in the molecule show effects biological activity potential. The sound interaction between the drug molecule with cucurbit[8]uril strongly advocates its possibility be used as a drug delivery system.

DFT insights into the structure, reactivity and radical scavenging activity of cycloartocarpesin

AbstractDaily increase in the number of patients suffering from illnesses due to reactive species has induced the permanent discovery and study of antioxidant compounds. The structure, reactivity, and antioxidant activity (AOA) of a phenolic compound named cycloartocarpesin (CAP), evaluated at DFT/B3LYP/6‐31 + G(d,p) level, is reported herein in the gas, pentyl ethanoate, and water phases. Bader topological analysis revealed that two of the three O‐H groups of CAP are involved in hydrogen bonds while the average local ionization energy (ALIE) and appropriate Fukui functions showed that electrons in the near vicinity of C7, C10, and C12 are the least tightly held and can easily be attacked by radicals. Analysis of the transition state of the reaction between CAP and HOO• radical shows that the proton coupled electron transfer process is not favored. Moreover, analyses of electronic spectra calculated at TD‐DFT/B3LYP/6‐31 + G(d,p) has interestingly demonstrate the ability of CAP to filtrate UVA, UVB, and UVC, thus exhibiting a photo‐protective activity.

Identifying the most energetic electrons in a molecule: The highest occupied molecular orbital and the average local ionization energy

The site of the greatest electronic density of the highest occupied molecular orbital (HOMO) is often taken to be the location of the most energetic electrons in a molecule, and thus the most likely site for reaction with an electrophile. However we show, by reference to the average local ionization energy on a molecular surface, that the HOMO alone often does not locate the most energetic electrons. This is because the HOMO, unlike the average local ionization energy, does not take explicit account of the fact that any molecular site has a significant probability of being occupied by electrons in lower-lying, less energetic molecular orbitals.