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The discharge of industrial wastewater, particularly from chemical and mining industries, poses significant threats to the environment, public health, and safety due to high concentrations of pollutants leading to serious illnesses and the loss of aquatic life. It is therefore essential and urgent to devise measures for mitigating these threats. To advance the understanding of graphene membranes for Arsenic (As) removal from wastewater, this research investigates As adsorption and its relative selectivity on graphene-based materials using computational approaches. Our study employed hybrid quantum mechanical calculations for energy and geometry optimization to explore As adsorption on pristine graphene membrane surfaces in vacuum and aqueous environments. We assessed the effect of different adsorption sites on the surface which includes the top (T), bridge (B), and hollow (H) sites across the edge (E) and center (C) regions of the absorbent surface, to identify the optimal site/mode of adsorption. Our results demonstrate that the edge sites are the most effective for adsorption, exhibiting strong adsorption energies in both vacuum (− 1.98 eV) and aqueous environments (− 1.97 eV). These values are significantly higher than the adsorption energies for water on the surface, which range from − 0.25 to − 0.26 eV. Geometrical analyses confirmed the bridge edge sites as the most preferred adsorption configuration. Our findings not only advance upon existing computational approaches for designing efficient adsorbents but also provide deeper insights into the adsorption mechanisms on graphene-based materials. Unlike previous studies, which focused primarily on experimental or theoretical aspects in isolation, this work integrates computational and theoretical approaches to optimize adsorption processes at the molecular level. By investigating membrane properties for As removal, this research offers a novel pathway for developing advanced adsorbents, addressing critical challenges in environmental remediation with greater precision and efficiency. [ABSTRACT FROM AUTHOR]

Due to the rapid development of the economy, increasing level of urbanization, and industrialization, air pollution has transformed from the traditional coal-fired type to the composite pollution of coal-fired type and motor vehicle exhaust. With this transformation, the excessive release of many gases results in drastic climatic changes, global warming, ozone layer depletion, and more, which dramatically affect human lives in many sectors including sports. Based on the above, this research employs the Generalized Additive Model (GAM) to study and predict the effect of atmospheric pollution on the health of soccer players. First, the paper evaluates the impact of air pollution on the physical health of soccer players. It starts with a rigorous evaluation of the influence of various atmospheric pollutants on the health of athletes. Second, it investigates data analysis using numerous tests, including the Augmented Dickey–Fuller test, to evaluate the stationarity of the data and choose the most suitable models for further examination. Third, the research explores the complex correlations between meteorological factors and atmospheric pollutants by considering the dynamic interplay of environmental variables on health results. This analysis offers a nuanced understanding of how meteorological conditions affect pollutant concentrations and their potential health implications. Finally, the research constructs a prediction model that incorporates these complicated associations by employing GAMs with cubic spline functions to capture the non-linear interactions among multiple factors influencing soccer players' health. This advanced modeling technique offers a full examination of air pollution's complex effects, opening the way for useful findings in the disciplines of public health, environmental management, and sports medicine. The experimental results show that the proposed GAM outperforms the other models in terms of accuracy (85%), precision (88%), F1-Score (87%), consistency (90%), recall (86%), specificity (91%), and sensitivity (82%). These remarkable achievements highlight the importance of the proposed GAM in predicting the effect of air pollution on soccer players' health. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• 13C SCS significantly correlates PM3 charge (q) of disubstituted benzene para carbon. • δ (13C SCS or q) = ρ F σ F + ρ R σ R o • The concept of π-polarization reflects the variation in ρ F. • Enhancement of ρ F parallels π-polarization stabilization of para carbon. • Generally, series' ρ R have the same trend of q,13C SCS and extended conjugation. The PM3 calculations of the Mulliken charge and the experimental 13C substituent chemical shifts (SCS) of para carbon for 17 para- disubstituted benzene series were investigated by correlation analysis. A significant correlation between the charge and the 13C SCS of the para carbon of the same series was observed. In mono-substituted benzene, the correlation of para 13C SCS with Mulliken charges calculated by PM3 and Mulliken charge calculated by DFT(B3LYP) with basis set 6 311(dp)G of the same carbon is similar. All the substituent effects on the charge and 13C SCS were modeled by the Reynolds' dual substituent parameter model (charge or 13C SCS = ρ F σ F + ρ R σ R o), where σ F and σ R o are the Reynolds' field and resonance constants, respectively, and ρ F and ρ R are the field and resonance effects, respectively. The coefficients of determination for all series were significant. The concept of π-polarization was used to analyze variation in ρ F. The interpretation of ρ F showed parallels between the charge and 13C SCS. An enhanced ρ F for a given series was attributed to the stabilization of the π-polarization charge at the para carbon. The ρ R was a function of extended conjugation within the side chain. Parallelism of charge and 13C SCS of the ρ R of the compared series were also observed, except in series with the reverse-substituent effect and the possession of a strong electronegative group, such as a nitro or azo group. [Display omitted] [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]

Quantitative Structure-Activities Relationship Analysis (QSAR) on the 1-aryl-tetrahydroisoquinoline derivative as a candidate for the anti-HIV drug (Human Immunodeficiency Virus) has been done. The analysis using an electronic descriptor of atomic net charge, dipole moment, polarization, HOMO-LUMO energy, and log P was calculated using the PM3 semiempirical method. The best equation model is determined using multilinear regression analysis. The QSAR analysis show that the best QSAR equation model of 1-aryl-tetrahydroisoquinoline derivatives: pEC50= -23.019-10.867(qC3)-162.911(qC4)-107.057(qC6) + 53.621(qC8) - 0.047 (µ) + 0.158 (a) + 0.175 (log P); (n = 36; r = 0.935; r² = 0.875; SE= 0.135927366; Fcount/Ftable= 7.945277618; PRESS = 2.857943). The compound with the higher activity value is the best theoretically derivative compound for the anti-HIV drug candidate. The new model of the 1-aryl-tetrahydroisoquinoline derivative from the design is expected to have better activity than the 1-aryltetrahydroisoquinoline derivative compound that already exists is 1-(6-acetylpyridine-2-yl)-7,8-methoxy-quinoline. [ABSTRACT FROM AUTHOR]

The spectroscopic data for a range of cyclopenta-[ d ][1,2,3]-triazine derivative dyes have been evaluated using various standard computational approaches. Absorption data of these dyes were obtained using the ZINDO/S semi-empirical model for vertical excitation energies of structures optimised with the AM1, PM3, and PM6 methods. These studies were conducted under vacuum and solution states using the polarisation continuum model (PCM) for implicit solvation in the linear response model. The accuracy, along with the modest computational costs of using the ZINDO/S prediction, combined with the PM3 optimisation method for absorption data was reliable. While a higher computational cost is required for the time-dependent density functional theory (TDDFT), this method offers a reliable method for calculating both the absorption and emission data for the dyes studied (using vertical and adiabatic excitation energies, respectively) via state-specific solvation. This research demonstrates the potential of computational approaches utilising solvation in evaluating the spectroscopic properties of dyes in the rational design of fluorescent probes. The spectroscopic analysis of cyclopenta-[ d ][1,2,3]-triazine derivatives was studied. TDDFT calculations corresponded to the experimental absorbance and emission data. Semi-empirical methods recorded a lower computational cost. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Semi-empirical PM3 calculations are made for the electronic absorption spectra of colored forms of nonmethylated anthocyanidins (aurantinidin, pelargonidin, cyanidin, and delphinidin). The position of the absorption band peak is shown to depend on the orientation of hydroxyl groups in the aglycone structure. The observed tendency toward a bathochromic shift after ОН groups are added to the ring generally corresponds to experimental data. The results for the uncharged quinonoid forms of pelargonidin (a hypsochromic shift of absorption bands) do not in this case agree with the prevailing opinion of specialists about the bathochromic shift. While this opinion is confirmed by DFT calculations, there are still no reliable experimental data on their validity. The formation of single-charged (negatively) quinonoid structures is clearly the reason for the bathochromic shift of absorption bands, which is consistent with the experimental data. When the charge multiplicity increases (to −2), a hypsochromic shift of absorption bands to the experimentally observed yellow color of anthocyanins in alkaline solutions is again predicted. [ABSTRACT FROM AUTHOR]

The theoretical study represents an essential preliminary stage for the start of any industry, as it gives a theoretical description of the properties of compounds (chemical, physical and biological properties) without conducting research to find out about this and the least cost. Through the theoretical study, we extract a clear picture of the chemical compounds before starting to manufacture them to know the extent of their impact on human health and their chemical and biological effectiveness. Using the Density Functional Theory (DFT/B3LYP) with base 6-311G, through Gaussian 09 program, the optimize geometry, (bond lengths, angles bond) and vibrational spectra was calculated of the benzimidazole derivatives [Carbenzim (CZM), Mebendazole (MBZ)]. Through orbital charts of HOMO and LUMO to study electronic properties. The HOMO-LUMO gap was also evaluated for chemical reactivity and determination of global reactivity descriptors (Hardness (h), Softness (S), Electrophilicity (w), Chemicalpotential (m), Electronegativity(χ))] that defines compunds effectiveness and the their biological activities. In addition, (QSAR) data has been used to develop relationships between biological activities and thermophysical properties of chemicals, through the Hyper Chem 8.0 program by using Semi-empirical (SE) method at the (PM3) level. The LOG P value was calculated, binding energy, Polarizability, hydration energy, surface area, and electrostatic potential energy difference of two level. [ABSTRACT FROM AUTHOR]

In this research, the possibility of using new suggested carriers (A) of vitamins (D3 and C) and amino acids (Leucine and Threonine) for diclofenac (Dc) drugs was addressed. Parameterization model 3 (PM3), unrestricted Harttre-Fock (UHF), unrestricted Density Functional Theory (U-DFT), and Docking have been used to calculate the reaction path of (O-A) bond rupture energies in diclofenac prodrugs (in vacuum). All were done at their optimize geometries by using Gaussian 09, Molecular Graphic Laboratory M.G.L. tools, Vina, BIOVIA (D.S.V.) and PyMol programs. The calculation involved the geometric structures, physical properties, lethal concentration (LC50), biological activity, and N.L.O. properties. Furthermore, the binding between Ribosomal protein S9 structure and the prodrugs in the liver were studied. Comparisons were made for the energies of the reactants, transition states, and products. The new carriers aim to improve the diclofenac drug's properties and provide new alternatives for the approved carriers. By examining the path of reaction of O-breakage energies, D3 and Threonine (Thr) represent a good prodrug due to their low heat of cracking (ΔHc), energy gap (ΔE), and activation energy (Ea#). At the same time, vitamin C and Leucine (Lue) showed a lower influence. In addition, LC50 showed theoretically that the maximum concentration of diclofenac carriers (Dc. A) was 9.290 × 10−10, 3.390 × 10−7, 6.762 × 10−7, and 1.125 × 10−6 M for Dc.D3, Dc.C, Dc.Leu, and Dc.Thr can be used, respectively. The order of the biological activity for the investigated carriers was Dc.D3 > Dc.C > Dc.Leu > Dc.Thr. The order of N.L.O. activity was Dc.D3 > Dc.Leu > Dc.C > Dc.Thr. In addition, the Autodock studies showed the ability of the suggested prodrugs to link with Ribosomal protein S9 structure in the liver for metabolism and producing an active drug (diclofenac acid). The suggested carriers were better than the common carriers (Na+ and K+) according to the binding energy.

AMBER/PM3 hybrid model allowed determining the structural properties of 5FU and imiquimod individually and after the adsorption of chitosan hydrogels crosslinked with genipin, respectively. It was observed that the Gibbs free energy (ΔG) decreases with the adsorption, but indicates thermodynamic stability and spontaneity in both processes; ΔG was verified by the increase in the dipole moments. On the one hand, the partition coefficient established the hydrophilic character with respect to the water present in the hydrogel, which increases with the adsorption. The FTIR showed that there were displacements in the signals, however, the hydrogen bond bands attributed to the formation of new bonds to perform the adsorption of the drugs were observed. The adsorption was verified by the MESP and the surface analysis, where the distribution of nucleophilic and electrophilic zone was observed.

A quantum‐chemical semi‐empirical PM3 and Gaussian 09 method has been used to evaluate the structure of a monolayer of α‐ and β‐cyclodextrins on a carbon surface. The adsorption energies for various types of packing of cyclodextrin molecules in a dense monolayer have been calculated. It has been established that the monolayers with the "sideway" orientation of the cyclodextrin molecules to the carbon surface are most energetically favorable. [ABSTRACT FROM AUTHOR]

In this work, we performed a theoretical density functional theory (DFT) and semi-empirical (PM3) analysis to calculate thermodynamic properties of biokerosene from coconut and palm kernel oils, Jet Propulsion Fuel 8 (JP-8), and mixtures of these fuels. All simulations were performed in thermal equilibrium and for a temperature range of 0.5–1500 K, considering the canonical ensemble model. We predicted the thermal properties energy, enthalpy, enthalpy change, Gibbs free energy, entropy, and specific heat at constant pressure with respect to temperature. In addition, we compared the performances of the DFT functional hybrid B3LYP and the basis set 6-311++G(d,p) and PM3 methods, in order to determine their accuracy for thermodynamic predictions relating to the fuels. Calculations for combustion enthalpy were carried out using the following methods: B3LYP/6-311++G(d,p), B3LYP/6-31+G(d), CBS-QB3, G3, G4, and G3/G4. The results showed good agreement with measured values, indicating that DFT may be a good method to calculate and predict thermodynamic properties of the combustion reactions of kerosene and biokerosene. [ABSTRACT FROM AUTHOR]

A research has been conducted to investigate the HKSA equation model of a set of carbamic derivative insecticidal compounds based on the hydrofobic, electronic and steric descriptors. The descriptors are calculated by a method of PM3 while the the insecticidal activity are obtained by the experiment. The relationship of the descriptos and the activities are determined by multilinear reggression analysis. The result of the analysis then provide a best equation model that can be used to design new carbamic derivative insecticidal compounds. These design might be recommended to be synthesized in the experimental works.

Naproxen (C14H14O3) is a non-steroidal anti-inflammatory drug (NSAID). It is important to investigate its structure to know the active groups and weak bonds responsible for medical activity. In the present study, naproxen was investigated by mass spectrometry (MS), thermal analysis (TA) measurements (TG/DTG and DTA) and confirmed by semi empirical molecular orbital (MO) calculation, using PM3 procedure. These calculations included, bond length, bond order, bond strain, partial charge distribution, ionization energy and heat of formation (ΔHf). The mass spectra and thermal analysis fragmentation pathways were proposed and compared to select the most suitable scheme representing the correct fragmentation pathway of the drug in both techniques. The PM3 procedure reveals that the primary cleavage site of the charged molecule is the rupture of the COOH group (lowest bond order and high strain) which followed by CH3 loss of the methoxy group. Thermal analysis of the neutral drug reveals a high response to the temperature variation with very fast rate. It decomposed in several sequential steps in the temperature range 80–400 °C. These mass losses appear as two endothermic and one exothermic peaks which required energy values of 255.42, 10.67 and 371.49 J g−1 respectively. The initial thermal ruptures are similar to that obtained by mass spectral fragmentation (COOH rupture). It was followed by the loss of the methyl group and finally by ethylene loss. Therefore, comparison between MS and TA helps in selection of the proper pathway representing its fragmentation. This comparison is successfully confirmed by MO-calculation.

A novel Si–Al porous clay material W (reprocessed from ceramic waste) was used for Acidovorax sp. strain PM3 immobilization to promote the growth of strains and improve nitrogen and phosphorus removal performance in water treatment systems. The porous clay material W was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy indicating that porous clay material W was a type of mullite with 63.52 m2/g specific surface area. After immobilization, the maximum biomass increased 2.7 times the specific growth rate and the removal rates of chemical oxygen demand (COD), ammonia (NH4+–N), and total phosphorus (TP) by the immobilized PM3 were 42.99, 29.19, and 11.76% higher than the free strain after 24 h. The Monod equation showed that the growth rate and processing speed of immobilized PM3 increased. The maximum adsorption capacities of COD and NH4+–N onto porous clay material W were 2.33 and 0.32 mg/g on the basis of Langmuir isotherm. The removal capacities of COD, NH4+–N, and TP by the immobilized PM3 were 588.24, 20.37, and 5.06 mg/l, respectively, as shown by kinetic studies. These results demonstrated that porous clay material W could improve the efficiency of microbial nitrogen and phosphorus removal, and the immobilized microorganism system could effectively treat domestic sewage. The adsorption isotherms can well describe the adsorption process. The maximum adsorption capacity of COD and NH4+–N on porous clay material W is 2.33 and 0.32 mg/g, respectively. Kinetic studies showed that the removal capacity of immobilized PM3 to COD, NH4+–N, and TP was 58.824, 20.37, and 5.06 mg/l, respectively. [ABSTRACT FROM AUTHOR]

The character table or the table of eigen values for the D7h point group, which is not found in the literature was constructed. The constructed table is used to classify all modes of the vibrational frequencies of the IR and Raman spectra for any compound or molecule that has the D7h symmetry in the Point Group. For that, it was used for classifying all the modes of vibrational frequencies of the [7] cyclacene (linear) monitoring molecule, possessing D7h symmetry. The constructed table was used to classify the symmetry species for the total degrees of freedom, total degrees of transition, total degrees of rotation and for the total degrees of modes of vibration (3N-6) for this tube. The character table was also used to determine the active and inactive modes of vibration in the IR and Raman spectra.Also,determining the polarized and non-polarized vibrational frequencies in the Raman spectrum, and used for describing the complete physical structure of the studied molecule after extracting its geometric shape. The methods of quantum mechanics calculations PM3 and DFT were used for this purpose applying the Gaussian 09 program. [ABSTRACT FROM AUTHOR]

• Semiempirical (PM3) and DFT (PBE1PBE/6-31G(d,p) were carried out. • HOMO-LUMO gaps were estimated for the β-CD-based molecular wires formed with polypyrroles. • The process of encapsulation does not affect the gaps calculated for the PPys oligomers. In the present paper, we performed a theoretical investigation via semiempirical and Density Functional Theory calculations in order to evaluate structural and electronic properties related to the native and push - pull derivatives oligomers of polypyrrole (PPys), as well as their respective molecular wires (MWs) formed from the encapsulation process of PPys into β-Cyclodextrin (β-CD). The HOMO-LUMO gaps (E g) for the PPys before and after the formation of β-CD based-MWs were calculated. As the main result, after the encapsulation process, there is a maintenance of the PPys semiconductivity, i.e., the process of complexation does not affect the E g. [ABSTRACT FROM AUTHOR]

Host-guest inclusion complexes between 2,6-dimethyl-ß-Cyclodextrin (DIMEB) and enantiomers of ibuprofen (R/S-IBP) were simulated using the molecular docking, semi-empirical PM3 and ONIOM2 (B3LYP/6-31g(d,p): PM3) methods. The modelling results showed that the most stable geometries of two R and S-IBP/DIMEB complexes were similar. It also showed that the binding energy of (R)-IBP/DIMEB and (S)-IBP/DIMEB complexes calculated by PM3 were -53.770 and -57.278 kJ/mol, while those calculated by ONIOM2 method referred to -52.917 and -59.053 kJ/mol similarly. In addition, thermodynamic parameters obtained to follow the trend of a binding energy value. Furthermore, the modelling indicated that (S)-IBP/DIMEB inclusion complex was more stable than (R)-IBP/DIMEB. DIMEB inclusion complex with S-enantiomer was stronger than Ibuprofen R-enantiomer. The theoretical results were in agreement with the experimental data. [ABSTRACT FROM AUTHOR]

In the molecule of title compound, C15H20O6, also known as cynarinin A, the cyclopentane ring having twist conformation and a γ-lactone ring assuming an envelope conformation are trans- and cis-fused, respectively, to a cycloheptane ring adopting a twist-chair conformation. In the crystal, O—H...O hydrogen bonds link neighbouring molecules, forming a three-dimensional network. Theoretical calculations of the molecular structure using the CNDO approximation and MOPAC PM3 geometry optimization are in satisfactory agreement with the results of the X-ray structure analysis.

Theoretical molecular structures of the ligand and its Co(II), Ni(II), Cu(II) and Zn(II) complexes have been studied using the semi-empirical quantum chemical methods. The experimental IR, electronic and NMR data of the investigated compounds are compared with the computational data. The ESP map and the natural atomic charge of the ligand was calculated to ascertain the reactive sites of the ligand. The experimental data agree well with the computational data. [ABSTRACT FROM AUTHOR]

N 1 ,N 4 -Bis{(2-hydroxyethyl)(methyl)carbamothioyl}terephthalamide (1A) was synthesized by reacting terephthaloyl chloride and ammonium thiocyanate and the product was reacted with 2-Methyl amino ethanol to afford the final product. The product was characterized by Infra Red, Nuclear Magnetic Resonance and Electrospray Ionization mass Spectrometric techniques. The crystal was obtained by recrystallization from DMSO by slow evaporation technique. The X-ray studies reveal that (1A) is crystallized in monoclinic system with space group P 21/n, a = 6.9727(9), b = 17.649(2), c = 8.2629(11), α = 90, β = 112.329(4), γ = 90. Z = 2 and V = 940.6(2). In the crystal structure, the molecules are linked by O(1) … H(1) … S(1), and O(1) … H(1) … O(2) intermolecular H-bonds forming a 3-D network. In addition, the antibacterial activities against four different strains of bacteria and theoretical evaluation for the stable geometries for (1A) has been performed using semi-empirical calculations of PM3 method. [ABSTRACT FROM AUTHOR]

AMBER/PM3 hybrid model allowed determining the structural properties of 5FU and imiquimod individually and after the adsorption in chitosan hydrogels crosslinked with genipin, respectively. It was observed that the Gibbs free energy (ΔG) decreases with the adsorption, but indicates thermodynamic stability and spontaneity in both processes; ΔG was verified by the increase in the dipole moments. On the one hand the partition coefficient established the hydrophilic character with respect to the water present in the hydrogel, which increases with the adsorption. The FTIR showed that there were displacements in the signals, however, the hydrogen bond bands attributed to the formation of new bonds to perform the adsorption of the drugs were observed. The adsorption was verified by the MESP and the surface analysis, where the distribution of nucleophilic and electrophilic zone was observed. [ABSTRACT FROM AUTHOR]

β-Cyclodextrin (β-CD) dimers have been prepared using the bioorthogonal Staudinger ligation for the first time. In addition to a known linker, methyl 2-(diphenylphosphanyl)terephthalate, a doubly active linker was specifically developed that enabled connection of two β-CD units in a single step and in aqueous/organic media, under mild conditions and with good yields. A three-carbon spacer between the β-CD torus and the azido group was required for facile dimer formation. The products, as studied by NMR spectroscopy, were found to adopt closed conformations by intramolecular self-inclusion. On the other hand, association via intermolecular binding was also observed in aqueous solution, confirmed by DOSY NMR experiments. Despite self-inclusion, the β-CD cavities were capable of guest encapsulation, as shown by titration experiments: the binding constant with 1-adamantylamine was similar to that of natural β-CD. Theoretical calculations for isolated molecules (PM3 level of theory) and in the presence of solvent [water, PM3(COSMO)] as well as DFT calculations suggested that the compounds prefer to adopt conformations which bring the phenyl groups either inside the β-CD cavity (inclusion) or over its narrow side (vicinal). Thus, Staudinger ligation could be the method of choice for linking CDs exhibiting (i) ease of preparation in aqueous media, in short steps, under mild conditions and in good yields, (ii) satisfactory aqueous solubility and independent binding capacity of the cavities.

Two azaphenanthrenes were synthesised by a facile synthetic pathway and characterised by X-ray crystallography. Molecular packing of 4-(2,4-dichlorophenyl)-2-methoxy-5,6-dihydrobenzo[h]quinoline-3-carbonitrile exhibits C–H...N and C–H...Cl hydrogen bonds in addition to intermolecular C–H...π, Cl...π and π...π (π-ring) stacking interactions. However, molecules of the 2-ethoxy derivative are linked into chains by one hydrogen bond of the C–H...N type and the crystal structure reveals an intermolecular C–H...π (π-ring) interaction. Computational studies by AM1, PM3, and density functional theory (DFT) techniques provide good approximations to the experimental X-ray data. The root mean square errors between the experimental and calculated bond lengths using AM1, PM3 and DFT methods for the 2-methoxy and 2-ethoxy derivatives are 0.0187, 0.0193, 0.0120 and 0.0197, 0.0195 and 0.0116 respectively. [ABSTRACT FROM AUTHOR]

Elucidating the brain basis for psychological processes and behavior is a fundamental aim of cognitive neuroscience. The lesion method, using voxel-based statistical analysis, is an important approach to this goal, identifying neural structures that are necessary for the support of specific mental operations, and complementing the strengths of functional imaging techniques. Lesion coverage in a population is by nature spatially heterogeneous and biased, systematically affecting the ability of lesion–deficit correlation methods to detect and localize functional associations. We have developed a simulator that allows investigators to model parameters in a lesion–deficit study and characterize the statistical bias in lesion deficit detection coverage that will result from specific assumptions. We used the simulator to assess the signal detection properties and localization accuracy of standard lesion–deficit correlation methods, under a simple truth model — that a critical region of interest (CR), when damaged, gives rise to a deficit. We considered voxel-based lesion-symptom mapping (VLSM) and proportional MAP-3 (PM3). Using regression analysis, we examined if the pattern of outcome statistics can be explained by simulation parameters, factors that are inherent to anatomic parcels, and lesion coverage of the population, which consisted of a representative sample of 351 subjects drawn from the Iowa Patient Registry. We examined the effect of using nonparametric versus parametric statistics to obtain thresholded maps and the effect of correcting for multiple comparisons using false discovery rate or cluster-based correction. Our results, which are derived from samples of realistic lesions, indicate that even a simple truth model yields localization errors that are systematic and pervasive, averaging 2 cm in the standard anatomic space, and tending to be directed towards areas of greater anatomic coverage. This displacement positions the center of mass of the detected region in a different anatomical region 87% of the time. This basic result is not affected by the choice of PM3 vs VLSM as the fundamental approach, nor is localization error ameliorated by incorporation of lesion size as a covariate in the VLSM approach, or by data distribution-driven approaches to controlling multiple spatial comparisons (false discovery rate or cluster-based correction approaches). Our simulations offer a quantitative basis for interpreting lesion studies in cognitive neuroscience. We suggest ways in which lesion simulation and analysis frameworks could be productively extended.

This paper reports a theoretical investigation using semiempirical and DFT calculations in order to evaluate structural and energetic properties related to the formation process of Cross-Linked β-Cyclodextrin molecular tubes. As result, TT spatial orientation was found to be the most favorable among the dimeric tubes. The overall stability order, TT > HH > HT, does not change with the number of cross-linking groups. Besides, we have shown that tubes with 3 cross-linking in their structures are the most stable ones due to steric and repulsion factors which is in perfect agreement with experimental data. [ABSTRACT FROM AUTHOR]

Naproxen (C14H14O3) is a non-steroidal anti-inflammatory drug (NSAID). It is important to investigate its structure to know the active groups and weak bonds responsible for medical activity. In the present study, naproxen was investigated by mass spectrometry (MS), thermal analysis (TA) measurements (TG/DTG and DTA) and confirmed by semi empirical molecular orbital (MO) calculation, using PM3 procedure. These calculations included, bond length, bond order, bond strain, partial charge distribution, ionization energy and heat of formation (ΔHf). The mass spectra and thermal analysis fragmentation pathways were proposed and compared to select the most suitable scheme representing the correct fragmentation pathway of the drug in both techniques. The PM3 procedure reveals that the primary cleavage site of the charged molecule is the rupture of the COOH group (lowest bond order and high strain) which followed by CH3 loss of the methoxy group. Thermal analysis of the neutral drug reveals a high response to the temperature variation with very fast rate. It decomposed in several sequential steps in the temperature range 80-400 °C. These mass losses appear as two endothermic and one exothermic peaks which required energy values of 255.42, 10.67 and 371.49 J g-1 respectively. The initial thermal ruptures are similar to that obtained by mass spectral fragmentation (COOH rupture). It was followed by the loss of the methyl group and finally by ethylene loss. Therefore, comparison between MS and TA helps in selection of the proper pathway representing its fragmentation. This comparison is successfully confirmed by MO-calculation. [ABSTRACT FROM AUTHOR]

Anti-leukemia screening of previously prepared isothiouronium and quaternary salts was performed, and some salts exhibited promising activity as anticancer agents. Quantum chemical calculations were utilized to explore the electronic structure and stability of these compounds. Computational studies have been carried out at the PM3 semiempirical molecular orbitals level, to establish the HOMO-LUMO, IP and ESP mapping of these compounds. The ADMET properties were also studied to gain a clear view of the potential oral bioavailability of these compounds. The surface properties calculated included critical micelle concentration (CMC), maximum surface excess (Γmax), minimum surface area (Amin), free energy of micellization (ΔGomic) and adsorption (ΔGoads).

The synthesis of the β-cyclodextrin/propiconazole nitrate inclusion complex and the advantages of the encapsulation of this drug were recently reported, but the experimental data only partially revealed the structure of the supramolecular complex due to the limitations in understanding the intermolecular association mechanism. The present work describes the equilibrium molecular geometries of β-cyclodextrin/propiconazole and β-cyclodextrin/protonated propiconazole, established by the AM1 and PM3 semi-empirical methods. The affinity between different parts of the guest molecule and the cyclodextrin cavity was studied considering that propiconazole possesses three residues able to be included into the host cavity through primary or secondary hydroxyl rims. The results have revealed that the most stable complex is formed when the azole residue of the propiconazole enters the cavity of the cyclodextrin through the narrow hydroxyl’s rim.

The structural and electronic properties of inclusion or interconnection between NT and PVC were studied by quantum semiepirical approximation method using (PM3) self-consistent ?eld molecular orbital method. The total structural energy, HOMO level energy, LUMO level energy, band gap?(E?_g ?=E?_HOMO-E_LUMO), and dipole moment of the compounds were calculated. Increasing the distance between NT and PVC led to decline the total energy difference which led to better interconnection between NT and PVC and vice versa when the distant is decreased. Therefore the more stable compound is f. The best electronic energies were obtained at the structures 3c and 3b in the first distance respectively. The dipole moments for all structures have the following trend: b> d > c > e > f > a> g.

Geometry and electronic structure of chiral carbon and carbon nitride (CNx) nanotubes were investigated through quantum chemical methods. Finite nanotubes with diameters ranging from 5 to 10 Å and containing up to 500 atoms were considered. CNx structures were built through random substitution of carbon atoms by nitrogen. The molecules were fully optimized by semi-empirical quantum chemical method (PM3). Our results show that the energy associated with nitrogen incorporation depends strongly upon the tube helicity and diameter. The doping of nanotubes with nitrogen contributes to reduce the stress caused by the small diameter of the studied systems. Density of States (DOS) results for pure carbon and CNx nanostructures, obtained through DFT and Hartree-Fock calculations, were analyzed. The introduction of nitrogen in the tube produce states in the gap region which characterizes the metallic behavior, as expected for these systems after N-doping.

The synthesis of C7- to C16-alkyl maltosides in the presence of tin(IV) chloride as Lewis acid catalyst was performed. The characterization of the products and theoretical investigation of the crucial step in the synthesis were carried out. The preparation of the β-maltosides required reaction time of 1 h, and that of the α-maltosides was 72 h. The side products were the α-D-maltosidechloride and 2-hydroxy-β-maltoside, respectively. The PM3 calculation confirmed the formation of the kinetically controlled β-product.

It has been known for some years about the presence of drugs excreted by humans in wastewater and its possible toxicological effects. Recently researchers are working on technologies that allow the degradation of these drugs and achieve an effective treatment of wastewater to be returned to the environment. Our interest in this study was to identify some molecular parameters of metoprolol, which is one of the most administered drugs for various cardiological treatments, and their major metabolites generated in the human body. Molecular and electronics properties were calculated using the semi-empirical PM3 calculations to conformations geometrically optimized, including map of electrostatic potential, HOMO-LUMO energies, dipole moments, heats of formation, LogP, ClogP, CMR and tPSA.

AM1 and PM3 methods were applied to investigate equilibrium geometries of inclusion complexes formed between 3-CD and neutral, anionic and cationic species of PABA (Para amino benzoic acid). 3-CD can bind to these three species (two possible orientations A or B) with negative binding energy, where the preference between A and Borientation of each PABA species is due to H-bond interaction. Finally, the HOMO and LUMO energies of each complex were calculated and compared.

The purpose of this work is to study theoretically stereoelectronic aspects of the interaction between heme and artemisinin in the transitional heme-artemisinin complex. Through semi-empirical calculations using the PM3 method, the potential energy barrier of artemisinin rotation relative to heme in the heme-artemisinin complex was studied in vacuum and in the partially solvated state. The minimum heat of formation obtained for the complex with and without water molecules is -702.39 and -100.86 kcal mol-1, respectively, which corresponds to the dihedral angle C-Fe-O1-O2 of 43.93º and 51.90º around the iron-oxygen O1 bond, respectively. The water molecules bind to heme via 13 hydrogen bonds and O-H•••O and 6 C-H•••O interactions, which accounts for -67.23 kcal mol-1. It is observed that the inclusion of water molecules does not affect significantly the stability of the heme-artemisinin complex.

In this study, the complexation of trans 3,5,3′,4′-tetrahydroxystilbene, also known as piceatannol (PIC), with β-cyclodextrin (β-CD) was investigated using the semi-empirical PM3 method in vacuum. Two orientations were assessed for the encapsulation of piceatannol in the cavity of β-cyclodextrin. The orientation in which the A aromatic ring of PIC was directed toward the inner cavity of β-CD was named ‘A’ and that in which the B aromatic ring is located inside the β-CD cavity was named ‘B’. The results indicated that both orientations were favorable for the complexation of PIC/β-CD. Indeed, the energy difference between the two orientations was less than 1 kcal/mol. Additionally, the negative interaction energies obtained for a 1:1 stoichiometry suggest that the complexation process is exothermic and indicate that the PIC/β-CD complex was highly stable and enthalpically driven. HOMO and LUMO investigations confirmed these results. [ABSTRACT FROM AUTHOR]

The interactions between carvacrol (CAR) and β-cyclodextrin (β-CD) have been analyzed employing PM3, ONIOM2 and DFT methods in vacuum and in water. Complexation, deformation, HOMO and LUMO energies were determined and discussed. Van der Waals interactions are mostly responsible for enthalpy driven complex formation of CAR with β-CD. Finally, TD-DFT of visible spectra and NBO calculations were analyzed and discussed. Theoretical studies propose that hydrophobic interaction and hydrogen bonding play significant role in determining the stability of the complexes. [ABSTRACT FROM AUTHOR]

Dexmedetomidine (4-[( S)-1-(2,3-dimethyl-phenyl)-ethyl]-1 H-imidazole), Dex, is potent agonist acting on α-adrenergic receptors (α-ARs). It can exist at the physiological pH in both forms: neutral and protonated. The results of receptor-independent and receptor-dependent studies applied to both forms of Dex are reported. A conformational analysis with PM3 semiempirical MO and ab initio HF/6-31G* methods was carried out for both forms of Dex. The calculated geometries of low-energy conformers of Dex were compared with X-ray geometry and those of conformers resulted from molecular docking of Dex in the binding pockets of 3D homology models of the α-, α-, and α-adrenoceptor subtypes. A MM/QM (molecular mechanics/quantum mechanics) docking study was performed to refine and optimize receptor-ligand complex and close contacts between the ligand and amino acids lining the binding cavity. Two-dimensional potential energy surface and docking results suggest that the imidazole ring can easily adopt the best orientation for an efficient interaction with the carboxylate group of Asp3.32 from the binding cavity of alpha2 adrenergic receptor subtypes. [ABSTRACT FROM AUTHOR]

A molecular docking study, using molecular mechanics calculations with AutoDock and semi-empirical PM3 calculations, was used to predict the enantiodiscrimination of heptakis(2,3,6-tri- O-methyl)-β-cyclodextrin (TMβCD) and ketoconazole (KTZ) enantiomers. A Density Functional Theory (DFT) single-point calculation at the level of B3LYP/6-311G (d,p) was performed for the PM3-optimized complexes to obtain more accurate binding energy and the electronic structures of the complexes. The difference in energies of the inclusion complexes between the KTZ enantiomers and TMβCD is probably a measure of chiral discrimination, which results in the separation of the enantiomers as observed in the experimental studies. Chirality 28:209-214, 2016. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]