B3LYP Density Functional Theory Research Articles

Molecular docking and spectroscopic exploration (FT‐IR, FT‐Raman) with HOMO–LUMO, ADMET, and 5,7‐dihydroxy‐2‐(4‐hydroxyphenyl) chroman‐4‐one against lung cancer: A potential uptake B‐RAF inhibitor

AbstractNaringenin has been proven to inhibit cell proliferation, which has anticancer properties. The role of Naringenin molecule in lung cancer and its processes are yet unknown. Naringenin is chemically called as 5,7‐dihydroxy‐2‐(4‐hydroxyphenyl) chroman‐4‐one, which was optimized geometrical parameters analysis such as bond length, bond angle and torsion angle were analyzed from Naringenin by utilizing Gaussian 09 W program. Characterizations of Naringenin analyzed by B3LYP density functional theory with basis set 6–311G (d,p). The energy value of Naringenin molecules are analyzed with (ground state) HOMO value −4.616, LUMO value for −0.169 (first excited state) energies and also predicted by energy cap value is 4.446. ADMET and drug likeness of the title compound was predicted, it's qualified with the Lipinski's rule of five. Naringenin molecular structural changes, distribution and also its reactive site investigated with MEP (Molecular Electrostatic Potential) analyses spans from −0.118eO to 0.118eO. The density of state (DOS) used to know molecular orbital contribution for selected compound. It was determined that Naringenin molecule in the active site of B‐RAF inhibitor (PDB code: 4MNF) has a binding energy of −8.9 based on a docking analysis and conformational changes. From this study, this drug will be expected to undergo essential future chemotherapy agent for lung cancer patient.

Two new cyclobutane derivatives of thiazolidin-4-ones: Synthesis, spectroscopic characterization, DFT quantum chemical calculations and determination of protonation constants

In the first stage of this study, 2-((4-(4-(3-methyl-3-phenylcyclobutyl)thiazol-2-yl)imino)thiazolidin-4-one (compound 1) and 2-((4-(3-(2,5-dimethylphenyl)-3-methylcyclobutyl)thiazol-2-yl)imino)thiazolidin-4-one (compound 2) were synthesized, characterized using FT-IR and NMR methods, and a combination of experimental and theoretical studies of the title compounds was performed. With the aid of the 6-311+G(d,p) basis set, all theoretical computations were performed using the density functional theory (DFT) B3LYP approach. The GIAO approximation was used to compute the chemical shifts of 1H and 13C-NMR. Theoretical calculations provide detailed information on chemical activity and molecular properties by determining electrophilic and nucleophilic properties. Accordingly, global chemical activity descriptors (FMOs, hardness, and softness parameters) were investigated, natural bond orbital (NBO) analyses were performed, thermodynamic properties at different temperatures were calculated, and the related relationships with temperature were obtained. The experimental and calculated NMR data presented consistent results for both compounds. R2 values for the 1H-NMR and 13C-NMR of compound 1 are 0.9914 and 0.9988, respectively. For the second compound, 2, these values are 0.9957 and 0.9962, respectively.In the second stage, the acid-base equilibria of title compounds containing cyclobutane, thiazole, and thiazolidinone functional groups were investigated potentiometrically in 60% dioxane-water media at room temperature and constant ionic strength. The values of the protonation constants determined in this study, logKNH(1) and logKNH(2), are related to the protonation of the azomethine nitrogen atom and the nitrogen atom on the thiazole ring, respectively. The sum of these values is the total protonation value of title compounds. The total protonation constants for compounds 1 and 2 are 10.59 and 10.58, respectively.

Synthesis, Characterization, Crystal structure determination and DFT study of a six coordinated Cu (II) complex of a phosphorous based tris-(2-pyridinylamino) phosphene sulphide ligand and its acid catalysed hydrolysis

One mono nuclear copper(II) complex (Cu-TPPS-OOCCH3 with structural formula C17H19CuN6O3PS) is synthesized using a novel tripodal tetradentate ligand, tris-(2-pyridinylamino)phosphene sulphide (TPPS), which has three pyridinylamino groups attached to a phosphorus atom connected to a sulphur atom (PS). The equatorial positions of the complex are occupied by three amino N-atoms of three aminopyridyl groups and one O-atom of the acetate group. The apical position is occupied by other O-atom of acetate group and one secondary N-atom of the tripodal ligand. The complex has been synthesized and purified as green solid and characterized by various spectroscopic techniques and the structure has been determined by X-ray single crystal diffraction study. The geometry optimizations and calculations of energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the compounds are performed by using the hybrid B3LYP density functional theory (DFT) along with the def2TZVP basis set.

Interdisciplinary insights into (1′R,3S,3′R)-1'-(4-chlorobenzoyl)-5′,6′,7′,7a′-tetrahydro-1′H dispiro[indoline-3,2′-pyrrolizine-3′,3″-indoline]-2,2″-dione: Structural, electronic, and molecular dynamics perspectives

In the field of heterocyclic compounds, the spiro-pyrrolidine and oxindole ring systems are highly esteemed due to their distinctive structural scaffold that is present in numerous pharmacologically significant alkaloids. Interdisciplinary research has been increasingly important in recent years for deciphering the intricate characteristics and behaviors of novel organic compounds. The current work uses quantum chemical computational techniques to study the structural stability and nonlinear optical (NLO) activity of (1′R,3S,3′R)-1'-(4-chlorobenzoyl)-5′,6′,7′,7a′-tetrahydro-1′H dispiro[indoline-3,2′-pyrrolizine-3′,3″-indoline]-2,2″-dione (DSOIP-Cl). The study combines molecular biology, computational chemistry, and theoretical chemistry knowledge to create a comprehensive picture of this fascinating organic compound. This study employed the density functional theory (DFT) B3LYP method to compute the electronic properties and molecular geometry. The basis set for the computations was 6–311++G(d,p). The IEFPCM solvation method is used to investigate the behavior of the head compound in different solvents. Understanding the interaction between organic compounds and the solvent phase is crucial because the majority of interactions in biological systems occur in solution. UV–Vis spectral analysis of the molecule in different solvents is performed using the TD-DFT method. The compound exhibits more excellent absorption in polar solvents such as water, while its absorption is lower in the gaseous phase. Assessing NLO properties revealed optoelectronics applications. DSOIP-Cl has 5.25 times the first-order hyperpolarizability of urea. Different solvents have higher dipole moments and first-order hyperpolarizability than gases. To identify the inter- and intramolecular charge transfer interactions, intermolecular hydrogen bonding, and hyperconjugative interactions that stabilize the structure, natural bond orbital (NBO) analysis is performed. A stabilization energy of 9.99 kcal/mol is obtained for π(C32–C33) → σ*(C33–C34) due to strong intramolecular hyperconjugative interactions. Frontier molecular orbital (FMO) analysis helps determine the global reactivity parameters and the charge transfer interaction. The van der Waals interaction and steric effect within the molecule are identified using RDG analysis. The pharmacokinetic properties, adherence to drug-likeness criteria, and easily controllable synthesis process were evaluated through ADME analysis, establishing it as an up-and-coming candidate for subsequent drug development. Ultimately, to determine the biological activity and the ability of the title compound to inhibit aldose reductase, a series of computational techniques are employed, including molecular docking study, molecular dynamic (MD) simulation, and MM-PBSA binding energy calculations. −7.86 kcal/mol was reported as the docking score. Hydrophobic interactions play an essential role in the efficiency of protein-ligand binding. The remarkable energetic contribution of DSOIP-Cl to the MM-PBSA binding dynamics highlights its unique association with the AR protein, with a binding energy of −79.81 kJ/mol.

Microwave spectroscopy and large amplitude motion of chlorosulfonic acid (ClSO2OH)

The high-resolution rotational spectrum of chlorosulfonic acid (ClSO2OH) has been studied using both broadband and cavity-based Fourier transform microwave spectrometers over the frequency range of 5–18 GHz. a-, b-, and c-type transitions have been recorded for both the 35Cl and 37Cl isotopologues. The observation of c-type lines establishes that the molecule lacks a plane of symmetry and suggests that the OH group can undergo large amplitude motion between equivalent structures. Interconversion between these structures can be achieved via internal rotation through two inequivalent barriers occurring at Cl-S-O-H torsional angles of 0 or 180degrees. As in previous work on triflic and methanesulfonic acids, two states are observed and are treated as tunneling states which are presumed to arise primarily due to motion through the lower of the two barriers. The a- and c-type transitions occur within each of these states while the b-type transitions cross between them. Rotational, centrifugal distortion, and chlorine nuclear quadrupole coupling constants, as well as the energy difference between the two tunneling states and associated coupling constants, have been determined. The experimental tunneling energies, ΔE, for the 35Cl and 37Cl isotopologues are 52.6926(16) MHz and 52.6397(46) MHz, respectively. Quantum chemical calculations were carried out using MP2 and B3LYP density functional theory (DFT) methods with an aug-cc-pVTZ basis set. The rotational constants from the optimized structures were in good agreement with the experimental values. The lowest energy barrier for OH motion was calculated to be 2.63 kcal/mol at the B3LYP/aug-cc-pVTZ level. The effects of the large amplitude motion are similar to those recently reported for triflic acid (CF3SO2OH) and methanesulfonic acid (CH3SO2OH). However, while the tunneling splittings in chlorosulfonic and triflic acids are virtually identical, they differ significantly from that of methanesulfonic acid.

Design, synthesis, and pharmacological efficacy of sonication-irradiated nanostructured transition metal (II) designed macrocyclic complexes

The synthesis of transition metal (II) complexes from aspartic acid was accomplished by using sonication irradiation in this work. Sonication irradiation is a straightforward and efficient technique for synthesis. Physiological and spectroscopic studies were carried out to investigate the process of assembling nanostructured complexes. Using the serial dilution (2-fold) and free radical scavenging (DPPH) procedures, the antioxidant and antibacterial activity were assessed, respectively. Various bacteria, including Gram-positive and Gram-negative strains and fungi, were tested to determine the antimicrobial efficacies of the macrocyclic ligand and its accompanying metal complexes. The inhibitory results on microbes showed that metal complexes had more potent antibacterial effects than their Schiff base ligands. The findings demonstrated that the biological activity had a positive impact. Sonication irradiation of some complexes increased the movement of those complexes at concentrations ranging from 3.125 to 6.250 μg/ml (MIC). The Gaussian 09 software was utilized to simulate the three-dimensional structure of the complexes, the chemical reactivity of the produced macrocyclic ligand, and the binding energy of its complexes’ EHOMO and ELUMO energies using the B3LYP Density Functional Theory (DFT) method. This method is well-suited for pharmaceutical applications in the real world since it requires little effort to set up, produces a high yield, and requires a relatively small amount of solvent.

Synthesis of bis-(benzhydryloxy) substituted axially silicon(IV) phthalocyanine: investigation of photophysical, photochemical, and computational electronic properties

Synthesis of axially disubstituted silicon(IV) phthalocyanine bearing benzhydryloxy groups obtained by reaction of SiPcCl2 with diphenylmethanol is reported. Characterization of the compound was performed by 1H and 13C NMR, UV–Vis, mass spectrometry, and FT-IR spectroscopy. Photophysical and photochemical properties were investigated. Fluorescence spectra measurements were performed in DMSO as solvent. A preferred chemical method was used to determine the amount of singlet oxygen production. Optimizations were calculated for the single-molecule Si-Pc with the 6–311 G (d, p) basis set at the B3LYP and B3PW91 levels of density functional theory (DFT). The charge transfer (or) charge delocalization between intramolecular donor–acceptor groups was determined by NBO analysis. Furthermore, molecular electrostatic potential, Fukui functions, electrophilic and nucleophilic character maps were calculated. The electronic structure and energy parameters of the investigated compound were determined to be ΔE calc = 2.19 eV by DFT calculation and ΔE opt = 1.84 by experimental UV spectrum.

In Silico Coformer Screening for Mefenamic Acid Cocrystallization

Cocrystallization is a widely used approach to enhance the solubility and dissolution characteristics of poorly soluble drugs. A pharmaceutical cocrystal is a multicomponent system composed of a solid active pharmaceutical ingredient (API) and a coformer, governed by non-covalent interactions. Screening for suitable coformers is essential to obtain an optimal cocrystal for specific drugs. This study aims to determine the drug-coformer interactions to select the most suitable coformer for cocrystal formation using the molecular docking method. Mefenamic acid, classified as a class II drug in the biopharmaceutical classification system (BCS), was used as the model drug. Two-dimensional structures of mefenamic acid (PubChem CID: 4044) and potential coformers were sourced from PubChem. Geometric optimization of all compounds was performed using GaussView 5.0.8 and Gaussian09 with the 3-21G basis set and Density Functional Theory (DFT) B3LYP method. The optimized compounds were prepared by adding hydrogen atoms and calculating Kollman partial charges using AutoDock 4.2. A grid box of size 40 Å × 40 Å × 40 Å was generated, with a maximum radius of 0.375 Å set as the surface distance in each simulation. A hundred conformations were run using the Lamarckian Genetic Algorithm. Interaction types and binding energies were analyzed using VMD 1.9.2 and BIOVIA Discovery Studio 2020 to compare interactions between mefenamic acid and each coformer. The results revealed that most coformer compounds formed interactions with mefenamic acid via hydrogen bonding and π–interactions. Saccharin demonstrated the most optimal interaction with mefenamic acid, with a binding free energy of –3.1 kcal/mol. Saccharin was identified as the most suitable coformer for mefenamic acid cocrystal formation based on the molecular docking study. Further experimental validation of saccharin is recommended to confirm its effectiveness in cocrystallization with mefenamic acid.

Unraveling the influence of biomaterial’s functional groups in Cd biosorption: a density functional theory calculation

Abstract Several biomass wastes, including forest wastes, bagasse, algae, and others, have been studied to determine their biosorption capability for adsorbing different ranges of heavy metals in the literature. Most experimental studies have not clearly shown the impact of functional groups in biomaterials discovered by FTIR analysis on the investigated biosorption processes. Because of this, the findings of this study indicate that it is necessary to theoretically investigate the influence of identified functional groups (as determined by FTIR analysis) on the biosorption activities of the sorbent or biomaterial prepared for the removal of cadmium metal from an effluent. Using the most geometrical structure for cadmium (Cd) metal, a series of identified functional groups for the sorbent were analyzed using FTIR to determine their mode and intensity of interaction to computationally understand better how they each influence the biosorption of cadmium. This was done to determine how each functional group contributes to the intensity of the cadmium biosorption, using a ground-state B3LYP density functional theory calculation performed in a Spartan 20 simulation package utilizing the 6-31G* and LANL2DZ > Kr basis sets. According to the study’s findings, carboxylate (–COO*) had the most significant effect on cadmium biosorption activity of all the functional groups studied due to the stronger binding strength obtained for it. Therefore, this research suggests exploring biomaterials with greater intensity for carboxylate function, which would aid cadmium sorption efficiency in an effluent treatment process.

Theoretical evidence for the enantioselectivity of Mannich reactions with fluorinated aromatic ketones

The enantioselective mechanism of the Mannich reaction with fluorinated aromatic ketones catalyzed by Zn/prophenol was examined using B3LYP density functional theory.

Exploration of 4-Chloro-3-nitrocoumarin: Spectroscopic Analysis, DFT Insights, Molecular Docking, Assessments of Antibacterial and In Vitro Anticancer Activities as a Potent Bioactive Agent

The detailed theoretical and experimental (FT-IR, FT-Raman, UV-visible) spectroscopy analyses of the 4-Chloro-3-nitrocoumarin (CNC) molecule were carried out. The CNC compound's pharmacological properties were also investigated utilizing antibacterial and anticancer activity investigations. Initially, the CNC molecule was optimized by the density functional theory B3LYP method with a cc-pVTZ basis set using the Gaussian 09W program. The optimized molecular structure provides the harmonic vibrational frequencies of the CNC molecule. The observed and computed vibrational wavenumbers were assigned and found to be well correlated. UV-Vis absorption spectrum analysis indicates that the molecule contains π→π* electronic transition. Frontier molecular orbitals (FMOs) analysis indicates that the LUMO of CNC molecule is mainly located over the nitro group, it indicates that the nitro group is particularly prone to accepting electrons from other molecules and participate in chemical reactions where acts as an electrophile. Mulliken atomic charge distribution analysis further confirms the FMOs results. The antibacterial test results validate that the CNC molecule exhibits a stronger inhibitory effect on Staphylococcus aureus compared to the other tested bacteria. In vitro anticancer cytotoxicity analysis clearly evidences that the CNC compound inhibits the growth of HeLa cervical cancer cell lines more than A549 lung cancer cell lines. In silico molecular docking study further validates that the CNC molecule inhibits the function of the p38a Mitogen-activated protein kinase 14, which has been associated with cervical cancer. As a result, the present study paves the way for the development of new drugs to treat cervical cancer.
 Keywords: 4-Chloro-3-nitrocoumarin; DFT; FT-IR; FT-Raman; Anticancer; Molecular docking; Cervical cancer drug.

TD-DFT calculation, equilibrium and kinetic adsorption study of removal of rose bengal dye by poly vinyl alcohol as a synthetic polymer adsorbent hybrid blend

Spectrophotometric study of the efficacy of the synthetic polymer such as polyvinyl alcohol in the removal of the dye Rose Bengal (RO) was examined. Different contact times, starting dye concentrations, adsorbent doses, dye solution temperatures, and pH values were tested. Density functional theory (DFT) with functional B3LYP and Hartree-Fock (HF) were used to investigate the optimal geometries, vibrational wavenumbers, vibrational band intensities, and atomic charges of 9VC. The researchers contrasted theoretical predictions for the basic vibrational modes with actual measurements. Using the functional B3LYP of DFT, we analyzed the hybrid organic dye (PVA+RO)HB such as the shape of geometry, electronic configuration, the capacity of polarizability, and second-order hyperpolarizability. The time-dependent density functional theory (TD- DFT), linked to a variety of hybrid functionals, was used in order to conduct research on the electronic absorption spectrum. Good agreement was found between the correlation coefficient values obtained from the Langmuir and Freundlich isotherm models, which were used to characterize the adsorption equilibrium. Pseudo-first-order kinetics was the best fit for the data on RO adsorption onto PVA. The values of enthalpy change and free energy change are negative and these confirm that our study concluded the exothermic and adsorption mechanism was spontaneous, respectively. The adsorption capacity was found to increase with increasing temperature. So, the kinetic parameters were evaluated from the temperature dependence of the adsorption capacity using the method of least squares.

Spectroscopic Characterization, Quantum Chemical, Molecular Docking, Antibacterial and Anticancer Studies on Ethyl Coumarin-3-Carboxylate: an Antibacterial and Lung Cancer Agent

The detailed theoretical and experimental (FT-IR, FT-Raman, UV-visible) spectroscopy analyses of the Ethyl Coumarin-3-Carboxylate (ECC) molecule were carried out. The ECC compound’s pharmacological properties were also investigated, utilizing antibacterial and anticancer activity investigations. Initially, the ECC molecule was optimized by the density functional theory B3LYP method with a 6-311 G++ (d,p) basis set using the Gaussian 09 W program. The optimized molecular structure provides the harmonic vibrational frequencies of the ECC molecule. The observed and computed vibrational wavenumbers were assigned and found to be well correlated. UV-Vis absorption spectrum analysis indicates that the molecule contains π →π* and n → π* electronic transitions. The Frontier molecular orbital analysis confirmed the molecular reactivity and bioactivity of ECC, while the Mulliken atomic charge distribution analysis pinpointed the molecule’s reactive sites. Antibacterial testing demonstrated the ECC compound’s inhibitory effect on various bacterial strains, with a particular impact on Klebsiella pneumonia. In vitro, anticancer assessments showcased ECC's stronger inhibitory effects on A549 lung cancer cell lines compared to HeLa cervical cancer cell lines. Additionally, in silico molecular docking investigations provided further validation that the ECC compound can inhibit the function of the epidermal growth factor receptor, a factor associated with lung cancer. As a result, this study lays the foundation for the development of novel drugs for lung cancer treatment.

Spectroscopic, Topological and NLO Activity of N N’ Diphenyl Thiourea Acetone Monosolvate: Experimental and Theoretical Approach

The compound N,N’-Diphenylthiourea acetone monosolvate was synthesized using slow evapouration technique and characterized by FT-IR, FT-Raman, UV-visible spectra. The optimized molecular geometry (bondlength, bondangle and dihedral angle), the complete vibrational frequency were calculated by using density functional theory (DFT) B3LYP method with the help of 6-31 G(d,p) basis set. The protonated N–H…O intermolecular interaction liable for the NLO activity was deliberated using DFT method along with experimental spectroscopic techniques. The inter and intramolecular interactions accountable for the stabilization of the material was done via NBO and AIM analysis. In addition, the molecular electrostatic potential, frontier molecular orbital, global reactivity descriptors, Hirshfeld surface and 2D-fingerprint was analyzed to acquire a greater understanding of the molecular effect. UV-Vis spectrum of DPTA crystal exhibits good optical transmittance in the spectral analysis. By using spectroflurometer technique the green band region was observed in fluorescence emission spectrum. The dipole moment, polarizability, first-order hyperpolarizability (α 0), related properties (β, α 0 and Δα) and second-order hyperpolarizabilties were calculated for the identification of non-linear optical activity of the molecule. The molecular docking studies were performed to investigate the binding affinity of legend with target receptor.

Computational Quantum Chemical Study, Insilco Molecular Docking and ADMET Study of (3E,5E)-3,5-Bis((1H-Indol-3-yl)Methylene)-1-Benzylpiperidin-4-One Derivatives

The title compound (3E,5E)-3,5-bis((1H-indol-3-yl)methylene)-1-benzylpiperidin-4-one (BIMBP) was deliberated optimal structure, data were calculated using the density functional theory (DFT) B3LYP method on 6-31 G (d, p) basis set and the experimental bond length and bond angles are compared with experimental data. The six-member piperidin-4-one ring adopts a chair conformation with the benzyl group occupying an equatorial position and the olefinic double bonds possessing an E configuration by DFT method. The stability and charge delocalization of the molecule were also studied by natural bond orbital (NBO) analysis. The calculated energies for the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) showed the stability and reactivity of the title compound. The molecular electrostatic potential (MEP) picture was drawn using the same level of theory to visualize the chemical reactivity and charge distribution on the molecule. The reported BIMBP molecule used as a potential NLO material since it has high μβ0 value. Molecular docking study performed for the synthesized compound revealed an efficient interaction with the antibacterial protease and resulted in good activities. Virtual ADMET studies were carried out as well and a relationship between biological, electronic, and physicochemical qualifications of the target compound was determined. Toxicity prediction by computational technique for the title compound was also carried out.

Crystal growth, structural insights, spectral, Z-scan, N[sbnd]H…O hydrogen bonding interaction and non-linear optical properties of the novelly synthesized 2-aminopyridinium cyanoacetate crystal

A novel organic single crystal 2-aminopyridinium cyanoacetate (2ACY) was synthesized and analysed by using UV–Vis, FT-IR, FT-Raman and single crystal X-ray diffraction experiments. Optically transparent and defect free crystal was grown from aqueous solution by slow evaporation technique at room temperature. All theoretical computations were carried out using the density functional theory (DFT) B3LYP approach using the basis set of 6–31+G(D). The grown crystal exhibits good optical transmittance in the UV–visible spectral analysis. The thermal behaviour of the 2ACY crystal has been analysed by TG/DTA analysis. Besides, the intermolecular interactions have been inquired and revealed by NBO analysis. Intermolecular contacts and molecular surface contours were analysed by using Hirshfeld and 2D fingerprint plot analysis. Topological analysis of electron localization function (ELF), localized orbital locator (LOL) and reduced density gradient(RDG) were evaluated. Additionally molecular electrostatic potential (MEP), HOMO-LUMO and charge analysis of the title compound have been investigated. The fluorescence behaviour of 2ACY crystal has been analysed in visible region and red colour emission is evidenced at 610 nm. The outcome of SXRD, UV-visible, TG/DTA, NLO, LDT and Z-scan values were compared with earlier reported compounds and amongst which the analysed compound 2ACY show good NLO activity. The occurrence of protonated intermolecular NH…O hydrogen bonding interaction liable for the nonlinear optical activity and it was projected using theoretical along with experimental techniques.

First-principles density functional theoretical study on the structures, reactivity and spectroscopic properties of (NH) and (OH) Tautomer's of 4-(methylsulfanyl)-3[(1Z)-1-(2-phenylhydrazinylidene) ethyl] quinoline-2(1H)-one

The tautomerizations mechanism of 4-(methylsulfanyl)-3[(1Z)-1-(2-phenylhydrazinylidene) ethyl] quinoline-2(1H)-one were inspected in the gas phase and ethanol using density function theory (DFT) M06-2X and B3LYP methods. Thermo-kinetic features of different conversion processes were estimated in temperature range 273–333 K using the Transition state theory (TST) accompanied with one dimensional Eckert tunneling correction (1D-Eck). Acidity and basicity were computed as well, and the computational results were compared against the experimental ones. Additionally, NMR, global descriptors, Fukui functions, NBO charges, and electrostatic potential (ESP) were discussed. From thermodynamics analysis, the keto form of 4-(methylsulfanyl)-3-[(1Z)-1-(2 phenylhydrazinylidene) quinoline-2(1H)-one is the most stable form in the gas phase and ethanol and the barrier heights required for tautomerization process were found to be high in the gas phase and ethanol ~ 38.80 and 37.35 kcal/mol, respectively. DFT methods were used for UV–Vis electronic spectra simulation and the time-dependent density functional theory solvation model (TDDFT-SMD) in acetonitrile compounds.

Interaction of bases and base pairs with polycyclic aromatic hydrocarbons as finite size model of graphene

Interaction of DNA bases and base pairs with polycyclic aromatic hydrocarbons (PAHs) as finite size models of graphene were studied theoretically using the Density Functional Theory (DFT). The finite size PAH optimized in a plane were used as finite size models of graphene. These structures were optimized at the B3LYP, B98 and MPW1PW91 functionals of DFT along with the 6–31G(d,p) basis set. For the stability of bases and base pairs, binding energies with and without basis set superposition error (BSSE) were calculated at mentioned levels. The calculated binding energies indicates that edges of PAHs are more feasible for reactions.

A DFT evaluation of molecular reactivity of volatile organic compounds in support of chemical ionization mass spectrometry

Gas-phase molecular properties of volatile organic compounds (VOCs) play an important role in the selection of gas-phase reagent ions for chemical ionization mass spectrometry (CI-MS). Chemical ionization-based mass spectrometry techniques such as proton transfer reaction mass spectrometry (PTR-MS) and selected ion flow-tube mass spectrometry (SIFT-MS) provide real-time, rapid, and online detection and quantification of VOCs using thermodynamics and kinetics of ion-molecule gas-phase reactions. We apply hybrid density functional theory (DFT) to compute proton affinity (PA), ionization energy (IE), and global reactivity parameters for VOCs, which are widely regarded as the primary sources of taints and off-flavors in wine. Atomic polar tensor (APT) charges and total energies at the stationary point for neutral and protonated molecules are also computed. PA and IE values determine the CI-MS mode of reactions, either proton transfer or electron transfer from the reagent gas ions to VOCs. Global reactivity parameters, such as chemical potential (μ), chemical hardness (η), softness (σ), and electrophilic nature (ω) as obtained from frontier molecular orbitals, are considered useful in rationalizing the chemical reactivity patterns of the molecules. A benchmark calculation of indole molecule with MP2, B3LYP, and M06-2X DFT methods at thermodynamically and kinetically stable protonation sites further supports the applied DFT method. Since limited data are available on computed parameters, the reported values would support CI-MS quantification of trace-level VOCs not only in wine but also in various food products.

Thermodynamic and Theoretical Studies of some N-substituted phthalimides Derivatives

N,N’-(biphenyl)bisphthalimide and N-(4’-amino __ biphenyl)phthalimide were chosen in this study to compare the stabilitytheoretically by density function theory (DFT) using B3LYP/6-31Gmethod, the electronic properties of these imides indicate that compound(N,N’-(biphenyl)bisphthalimide) is more stable than the compound (N-(4’-aminobiphenyl) phthalimide) by (-0.8422 eV or -19.4215 Keal.mo!'')depending on the values of HOMO, synthesis _ reaction of imide isspontaneous and endothermic at temperature 150°C according to the valuesof A,S, A,G and A,H thermodynamically.INTRODUCTION Imides are organic compounds for N-monoacy] derivatives of amidewhich may be open or cyclic chain. Cyclic imide constitute an importantclass of compounds possessing bis-amide linkage with common nitrogen.Imide very important molecules because their activity as antibacterial,antifungal, anti nociceptive, anticonvulsant and antitumor!, They havebeen useful building blocks in the synthesis of natural products’! and otherheterocycles as well!*!, Their ability to cross biological membranes in-vivo,due to their hydrophobicity is well established'“!,The preparation of imideshas received considerable attention during recent year A number ofmethods such as acylation of amides with acyl chlorides, anhydrides andcarboxylic esters or acids), amino carbonylation of aryl bromides'*! havebeen reported for the preparation of acyclic imides.COMPUTATIONAL METHODS Molecular geometries of the all molecules were fully optimized withthe hybrid density functional theory (DFT) B3LYP method!”"'"! using the6-31G basis set!!?!3! by means of the Gaussian 09, revision A.02!"4! usedfor all geometry optimizitions, thermodynamic functions at conditions