Mulliken Atomic Charges Research Articles

Spectroscopic, computational, electronic state and non-linear optical analysis on 1, 8-dihydroxyanthraquinone by density functional theory

The titled compound studied spectroscopically by UV–visible, FT-IR, FT-Raman in addition to quantum chemically through a density functional approach. B3LYP hybrid function/6-311++G (d, p) basis-set utilizes to optimize structure as well as determine normal modes of vibrations. Time-dependent density functional theory together with PCM solvent model applied for various electronic properties (in gas-phase, methanol, acetone, ethanol, DMSO), correlated with experimental UV–Vis spectra. HOMO-LUMO energy outcomes highlight charge transfer that happened inside the molecule. The Fukui functions, molecular electrostatic potential surface, mulliken atomic charge distribution, and NBO analysis confirm reactive and bioactive nature. All non-linear optical action of 1,8 DHAQ was measured through a similar basis set. All quantum chemical computational efforts have completed via Gaussian 09W application software with Gauss-View 6.0.6. The outcomes recommend that hydroxy-substituted Anthraquinone dye can be a good candidate for an optoelectronics, photonics, and pharmaceuticals industries.

Structural and spectral properties of 4-(4-(1-(4-Hydroxyphenyl)-1-phenylethyl)phenoxy)phthalonitrile: Analysis by TD-DFT method, ADME analysis and docking studies

Since phthalonitrile compounds have become popular lately, the focus has been on the idea that these compounds should be investigated. A unique phthalonitrile compound, 4-(4-(1-(4-hydroxyphenyl)-1-phenylethyl)phenoxy)phthalonitrile (coded as PN) was selected and molecular modeling studies were carried out on this compound to be brought to the literature. First, time-dependent density functional theory (TD-DFT) calculations (Geometry optimization, HOMO-LUMO, dipole moment calculations, MEPS maps, Mulliken atomic charges, and NBO analysis) were performed for PN. In addition, in this section, absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis for the compound belonging to the phthalonitrile group was performed and the color regions were presented separately. Finally, molecular docking studies were performed for two compounds separately with three different enzymes (AchE, BchE, α-GLY), and docking scores and receptor models were presented.

Experimental (FT-IR, 13C/1H-NMR) and DFT (B3LYP, B3PW91) Studies of 3-n-Propyl-4-[2-(4-Methoxybenzoxy)-3-Methoxy] Benzylidenamino-4,5-Dihydro-1h-1,2,4-Triazol-5-Ones Molecule

All theoretical calculations of 3-n-propyl-4-[2-(4-methoxybenzoxy)-3-methoxy] benzylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-ones has been performed with B3LYP/B3PW91 functions of DFT method using the 6-311G(d,p) basis set (Frisch et al., 2009; Wolinski et. al., 1990). Firstly, optimized to achieve the most stable form of the molecule. Then, the veda4f program was used in defining Infrared (IR) data (Jamróz, 2004). The standard error values were found via the Sigma plot with regression coefficient of a and b constants. The vibrational frequency values of this molecule have been calculated by using 6-311G(d,p) basis set with DFT (B3LYP/ B3PW91) methods. Then, these values are scaled with appropriate scala factors (Merrick et al., 2007). 1H-NMR and 13C-NMR spectral values according to GIAO method (Wolinski et al., 1990) was calculated using Gaussian G09W program package in DMSO solvent and in gas phase. Theoretical spectral values of molecule were compared with experimental values. Experimental data obtained from the literature (Alkan et al., 2014). In addition, electronic properties (electronegativity (χ), global hardness (η), electron affinity (A), ionization potential (I), softness (σ), thermodynamics properties (heat capacity CV0, entropy S0 and enthalpy H0), HOMO-LUMO energy, ELUMO-EHOMO energy gap (ΔEg), geometric properties (bond angles, bond lengths), dipole moments, Mulliken atomic charges, total energy of the molecule were calculated. Finally, the molecular surfaces such as the electron density, molecular electrostatic potential (MEP), contour and the total density maps were designated.

Synthesis, spectroscopic characterization, molecular docking and in vitro cytotoxicity investigations on 8-Amino-6-Methoxy Quinolinium Picrate: a novel breast cancer drug

Density Functional Theory (DFT) studies of the 8-Amino-6-Methoxy Quinolinium Picrate (8A6MQP) molecule have been carried out with extensive and accurate investigations of detailed vibrational and spectroscopic investigations as well as validated experimentally. The 8A6MQP sample was synthesized and characterized using FT-IR, FT-Raman, FT-NMR and UV-Vis spectroscopic techniques. Subsequently, the optimized molecular structure and harmonic resonance frequencies of the molecule were computed based on DFT/B3LYP method with a 6-311G++(d,p) basis set using the Gaussian 09 program. The experimental and calculated vibrational wavenumbers were assigned. The absorption spectrum of the molecule was computed in the liquid phase (ethanol), which exhibits n to л* electronic transition and compared with the observed UV-Vis spectrum. Frontier molecular orbital analysis shows the molecular reactivity and kinetic stability of the molecule. The Mulliken atomic charge distribution and molecular electrostatic potential surface analysis of the molecule validate the reactive site of the molecule. The natural bond orbital analysis proves the bioactivity of the molecule. Molecular docking analysis indicates that the 8A6MQP molecule inhibits the action of DNA topoisomerase 2-alpha protein, which is associated with breast cancer. In addition, the in vitro cytotoxicity analysis of the 8A6MQP molecule against human cervical cancer cell lines (ME180) and human breast cancer cell lines (MDA MB 231) were determined by MTT assay, which evidences that the title molecule exhibits higher inhibition against the breast cancer cell lines compared to that of cervical cancer cell lines. Hence, the present study paves the way for the development of novel drugs in the treatment of breast cancer. Communicated by Ramaswamy H. Sarma

Theoretical (6-311G(d,p)/ 3-21G) and Spectroscopic (13C/ 1H-NMR, FT-IR) Analyses pf 3-Propyl-4-[3-(2-Methylbenzoxy)-Benzylidenamino]-4,5-Dihydro-1h-1,2,4-Triazol-5-One Molecule

The molecule was studied with the method Density Functional Theory (DFT) using two different the basis sets (6-311G(d,p)/ 3-21G) in the Gaussian 09W program. First, the most stable three-dimensional shape of the molecule was determined with the GaussView5.0 program (Dennington et al., 2009). Based on the structure of this optimized molecule,"spectroscopic properties"(FT-IR, 13C/ 1H-NMR), the electronic properties (electron affinity (A), ionization potential (I), electronegativity (χ), chemical hardness and softness, electrophilic and nucleophilic index), HOMO-LUMO energies and ΔEg energy, the geometric properties (bond length and angle) ve the thermodynamic properties (thermal energy (E), thermal capacity (CV), entropy (S)) were calculated with DFT/ 6-311G(d,p) and 3-21G. In addition, the total energy of the molecule, mulliken atomic charge values, dipole moment, molecular electron potential (MEP), total density and contour surface maps were determined. The electrophilic and nucleophilic regions of the structure were confirmed. Theoretical calculations of 13C/ 1H-NMR isotropic shift values were performed in gas phase and solvent (DMSO) acording to GIAO method and regression analyzes were by compare with experimental values of computational data. R2 values were calculated and regression graphs were created. FT-IR (Infrared) vibration frequency values were calculated from the Veda4f program. The theoretical vibration frequency values were compared with the experimental IR values. Experimental data obtained from the literature.

Theoretical and Experimentical Properties of 3-Ethyl-4-(3-Acetoxy-4-Methoxy-Benzylidenamino)-4,5-Dihydro-1H-1,2,4-Triazol-5-One

In the theoretical study, the 3-ethyl-4-(3-acetoxy-4-methoxy-benzylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-one has been optimized using B3LYP/6-311G(d) basis set. 1H-NMR and 13C-NMR isotropic shift values were calculated by the method of GIAO using the program package Gaussian G09. Experimental and theoretical values were inserted into the graphic according to equitation of δ exp=a+b. δ calc. The standard error values were found via SigmaPlot program with regression coefficient of a and b constants. IR absorption frequencies of this compound were calculated with same method. Theoretically calculated IR data are multiplied with appropriate adjustment factors and the data obtained according to DFT method are formed using theoretical infrared spectrum. The veda4f program was used in defining IR data which were calculated theoretically. The thermodynamic parameters, HOMO and LUMO energies, electronic properties, Mulliken atomic charges of titled compound has been investigated by using Gaussian 09W program. The spectroscopic data of this compound has been calculated by using 6-311G(d) basis set with density functional method (DFT/B3LYP) and compared with experimental values.

Computational Chemistry: Sulfamic Acid Catalyzed PEG-400 Mediated Synthesis, Molecular Structure, HOMO–LUMO, UV-visible, Vibrational, and Reactivity Descriptors Analysis of 2-(Furan-2-yl)-1H-benzo[d]imidazole

2-(Furan-2-yl)-1H-benzo[d]imidazole (2-FBI) is synthesized and investigated using computational chemistry in the present analysis. PEG-400 and catalytic amount of sulfamic acid presents green protocol for the synthesis of 2-FBI. FT-IR, 1H NMR, and 13C NMR spectroscopic methods were used to characterize the structure of 2-FBI. The density functional theory (DFT) approach was used to perform the theoretical calculations, with a basis set of 6-311++G(d,p). Theoretical and experimental UV-Visible investigation is correlated to obtain better insights into the absorption spectral studies. The experimental vibrational frequencies were compared with the scaled vibrational frequencies for the assignment of vibrational bands. Molecular electrostatic surface potential and Mulliken atomic charges are employed for the determination of charge density and reactive sites. In addition, the more precise computation of Mulliken atomic charges is done by comparing 6-311++G(d,p) and 6-311G(d,p) basis sets. DOI: http://dx.doi.org/10.17807/orbital.v13i5.1625

Synthesis, spectral and antimicrobial studies of some 3-Arylideneamino-1,2,3-triarylpropan-1-ones

In this work, -amino ketones or esters were used to manufacture a new chemical called 3-arylideneamino-1,2,3-triarylpropan-1-ones (1–5). The geometries were distinguished using FT-IR, 1H, and 13C NMR spectroscopy. DFT investigations were used to improve the molecular geometry of the selected molecules (1–5). The HOMO and LUMO energies, as well as the Mulliken atomic charges, were determined. HOMO-LUMO computations were also used to quantify and assess electrochemical variables such as chemical hardness and electronegativity. Antibacterial and antifungal activity has been tested on all of the substances. Compounds 2, 3, and 4 were discovered to have potent antibacterial properties. Compound 2 was discovered to be the most effective against Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiellapneumoniae bacteria.

Synthesis, growth, experimental, and theoretical characterization of 6-amino-1H-pyrimidine-2,4-dione dimethylacetamide single crystal

The single crystals of nonlinear optical organic compounds are essential for their use in optical devices. With this purpose, this research presents the formation of good quality single crystals of 6-amino-1H-pyrimidine-2,4-dione dimethylacetamide from an aqueous solution at room temperature by following the slow evaporation solution growth technique. While single crystal X-Ray Diffraction (SXRD) analysis was used to examine the structural properties of the grown crystal, Powder X-Ray Diffraction (PXRD) was employed toconfirm its crystalline nature and phase purity. The presence of the various functional groups was verified using Fourier Transform Infrared (FTIR) spectral analysis. The UV-vis-NIR spectrum was recorded to investigate the optical transparency of the grown crystal.Hirshfeld surface analysis was carried out to further examine the possibly present intermolecular interactions. Finally, the structure of the crystal was optimized using the DFT/B3LYP/3-21G(d,p)level combined with the DFT/B3LYP/6-311++G(d,p) level to study the molecular properties of the grown crystal such as stable configuration, dipole moment, polarizability, hyperpolarizability Nuclear Magnetic Resonance (NMR), Natural Bond Orbital (NBO) theory, and Mulliken's atomic charges in the gaseous state.

Synthesis, characterization and electrochemical behavior for API 5L X70 carbon steel in 5% sulfamic acid medium using PVVH/PEMA blend filled with gold nanoparticles

In the present work, we synthesized the polymer blend of Poly (vinyl chloride-co-vinyl acetate-co-2-hydroxypropyl acrylate), and Poly (ethyl methacrylate) (PEMA) by solution casting method and then filled it with different concentrations of gold nanoparticles (Au-NPs). The present composite was employed as corrosion inhibitors for API 5L X70 carbon steel in 5% sulfamic acid solution by electrochemical methods such as potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) techniques. The quantum chemical computations utilized by DFT process produced an acceptable theoretical interpretation for the adsorption and inhibition performance of the composite on the carbon steel surface. PP plots demonstrated that the examined samples act as a miscellaneous type inhibitor. With raising its concentrations, the inhibition productivity rises up to 91.3% in case of blend/ 3% Au-NPs as observed from the EIS results. The inhibition mechanism follows Langmuir adsorption isotherm. It was discussed as concerns the nanocomposite investigated adsorption on steel metal surface and confirmed using SEM. Bode plots exposed that, the total impedance elevated with raising examined polymer concentration and the constant addition to the phase angle move was clearly associated with the increasing of the examined polymer concentration adsorbed on carbon steel species. A significant agreement was attained among the quantum chemical variables (DFT and Mulliken atomic charges) and the experimental computations, indicating the efficiency of the nanocomposite to act as effective corrosion inhibitor.

Spectroscopic (UV and fluorescence), biological, DFT and molecular docking studies of 3,5‐diethyl‐2r,6c‐di(4‐fluorophenyl)piperidin‐4‐one picrate

AbstractThe spectroscopic investigations of 3,5‐diethyl‐2r,6c‐di(4‐fluorophenyl)piperidin‐4‐one picrate (3,5‐DEDFPP) are evaluated by UV–Vis and fluorescence techniques. At the B3LYP/6‐311++G(d,p) level of theory, the DFT approach was utilized to optimize the molecular structure. The dipole moment, polarizability, and hyperpolarizability values are calculated at same level of theory. NBO analysis was used to calculate the hyperconjugative interaction energy (E(2)) and electron densities of donor (i) and acceptor (j) bonds. The molecule's energy gap was discovered using HOMO and LUMO calculation. The Mulliken atomic charges of the carbon, nitrogen and oxygen atoms were calculated and using at the same level. The thermodynamic properties of the title compound were calculated at different temperatures in gas phase. The 3,5‐DEDFPP's bacterial activity was evaluated against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Vibreo cholerae, and Pseudomonas aeruginosa, as well as fungal strains such as Candida albicans, Aspergillus niger, Aspergillus flavus, and Trichophyton rubrum. The interaction of the title compound to bind to a target protein was studied using molecular docking analysis.

First-principles study on B2 based XAl(X = Rh, Ru)compounds

In this study, to see pressure effects on optical, thermodynamic, structural, elastic, electronic properties, charge density, and phonon frequencies of the XAl (X:Rh, Ru) compounds in B2 structure, the first-principles methods were used. The ground-state properties of these compounds were determined and compared with experimental and theoretical data. High Young’s and shear modulus showed these compounds to be hard materials. The investigated compounds have ductile property according to the Paugh criterion and Poisson’s ratio calculated from elastic constants. The electronic band structure showed that these compounds have a metallic nature. Dynamic stability using phonon distribution curves was determined under pressure. The bond properties between Rh-Al and Ru-Al atoms were evaluated in detail by Mulliken Atomic Populations and charge density analysis. Also, the optical properties are examined in detail. We think that this theoretical work contributes greatly to engineering applications due to the electronic, thermodynamic, and optical behavior of XAl (X: Rh, Ru) compounds.

Preparation, DFT and optical nonlinear studies of a novel azo-(β)- diketone dye

New azo compound containing an antipyrine moiety is prepared via interaction of 4-aminoantipyrine with benzoylacetone. The coupling reaction of diazonium salt with benzoylacetone is employed to prepare the azo compound. The FTIR, 1H NMR and mass spectroscopies are used for the characterization of the new azo compound. Density function theory DFT calculations are carried out to study the electronic structure and vibrational frequencies of the prepared azo compound. A linear correlation appeared between the Mulliken atomic charge of oxygen atoms and the values of calculated wavenumbers. The nonlinear optical NLO properties of the prepared compound solution are studied using 473 nm, continuous wave cw, single fundamental mode, low power laser beam via the diffraction ring patterns DRPs and the Z-scan techniques. The optical limiting OLg property of the compound solution is examined. The DRPs are simulated numerically using the Fresnel-Kirchhoff integral with reasonable accord compared to the experimental findings.

Structural, spectral elucidation, wavefunctional properties, natural bond orbitals, and molecular docking analysis of synthesized 1-phenyl-3(4-methoxyphenyl)-2-propenone: protease kinase inhibitor

In this present work, structural, spectral, and electronic properties of newly synthesized 1-phenyl-3(4-methoxyphenyl)-2-propenone compounds are examined by making the use of the density functional theory Gaussian 16 W tool. Optimized structural parameters, topological properties (Electron localization function and Localized orbital locators) are investigated in the aqueous phase. Experimental spectroscopic (Fourier transform infrared spectroscopy and Fourier transform Raman spectroscopy) investigation and quantum chemical analysis are performed on the title compound. Non-covalent interaction analysis is performed in different solutions. Bandgap energies are calculated from molecular orbital energies in various solvent atmospheres. Electrophilic site strength of headline compound is identified and analyzed from molecular electrostatic potential surface and Mulliken atomic charges analysis in different polar and non-polar liquids. Experimental and theoretical chemical shift values are recorded and predicted in a nonpolar solvent by Nuclear magnetic resonance spectral investigation. Hyperconjucative interactions are studied from the natural bond orbitals method. Drug likeness and mol inspiration properties are calculated. Moreover, a Molecular docking study is performed with breast cancer and anti-malarial receptors.

Microwave-assisted synthesis, DFT theoretical study and biological activities evaluation of two phosphonylated m-toluidine derivatives

An easy and efficient microwave-assisted method has been developed for the synthesis of two phosphonylated molecules: α-aminophosphonic acid (MTA) and α-aminophosphonate ester (MTE). To achieve these, we have synthesized the products from m-toluidine, under microwave conditions. All of the obtained compounds were characterized by Microanalysis, UV–Vis, FT-IR, and 1H, 13C and 31P NMR spectroscopic methods. The spectral results are in good line with the proposed structures. Density Functional theory (DFT) calculations were carried out using Gaussian09 program package, using 6–31G++(d,p) basis set. The frontier orbital energies were presented and have been used to predict global reactivity indices. Results showed that MTE is more reactive and less stable than MTA. The Mulliken atomic charges, dipole moment and thermodynamic proprieties were also calculated and discussed. In addition, the target compounds were evaluated for their in vitro antioxidant, antimicrobial and antienzymatic activities. The biological assays indicated that these compounds displayed potent inhibitory activity toward acetylcholinesterase (MTE: 92.71±0.91%, MTA: 67.32±0.52%) and butyrylcholinesterase (MTE: 79.16±0.47% and MTA 34.80±0.76%). It was also found that they act as excellent antiradical agents (ABTS: MTA/226.077±0.29 μg/ml, MTE/ 535,993±0.30 μg/ml and DPPH: MTA/311.853 ± 0.14 μg/ml, MTE/621.627 ± 0.12 μg/ml). In addition, these compounds exhibited the highest antibacterial and antifungal properties.

Synthesis, structural characterization, Hirshfeld surface analysis and third-order nonlinear optical properties of Schiff bases derived from 1,1-diphenylmethylamine

Two Schiff bases namely, (E)-4-((benzhydrylimino) methyl)-N,N-dimethylaniline (I) and (E)-N-(4-isopropylbenzylidene)-1,1-diphenyl methanamine (II) were synthesized by one pot condensation reaction. The structures were confirmed by single-crystal X-ray diffraction (SXRD) analysis. The molecules are associated by C‒H···π and π···π interactions which are responsible for the formation of supramolecular network. The compounds are further characterized by FT-IR, 1H and 13C NMR spectral analysis. The UV–Vis-NIR and photoluminescence spectral data of the compounds were studied to explore the optical transmission and emission properties respectively. The surface morphological changes in the compounds were observed by scanning electron microscopic (SEM) analysis. TG-DTA methods were used to point out the thermal stability of the compounds. The third-order nonlinear optical property was investigated in detail using Z-scan technique. The optimized geometry, molecular electrostatic potential (MEP) maps, Mulliken atomic charge distribution and first-order molecular hyperpolarizability were calculated using density functional theory (DFT) calculations using the B3LYP method with 6–311 G as basis set. Intermolecular interactions were studied using 3D Hirshfeld surface maps and the percentage contributions of various interactions are studied and quantified by 2D fingerprint plots.

Ag modification of SBA-15 and MCM-41 mesoporous materials as sorbents of thiophene

Zeolites and some mesoporous materials modified by Ag possess excellent desulfurization performances toward the adsorption of thiophenic compounds. However, Ag in Ag-based sorbents has different forms, and the interactions between different forms of silver and thiophene still require further studies. In this paper, pure silica SBA-15 and MCM-41 mesoporous materials with weak acidity were loaded with Ag from the silver ammonia solution to form Ag/SBA-15 and Ag/MCM-41 sorbents. By comparing the desulfurization efficiencies of the sorbents in the simulated solution of thiophene-cyclohexane, thiophene-benzene, tetrahydrothiophene-cyclohexane and tetrahydrothiophene-benzene, it is found that the adsorption of sorbent for thiophene was accompanied by S-Ag and π complexation, and the adsorption performances of thiophene by the sorbents were greatly affected by benzene. The XPS results show that most Ag in Ag/SBA-15 and Ag/MCM-41 sorbents was metallic Ag, and some Ag strongly interacting with the carrier led to the formation of Ag-O-Si bonds as the main active center of thiophenic compounds. In addition, the sulfur atomic mulliken charges (e-) of different thiopheic compounds (thiophene, tetrahydrothiophene, methylthiophene) will affect the interactions between active components Ag and thiophene sulfur compounds. The desulfurization efficiencies of the sorbents in thiophene-cyclohexane, 2-methylthiophene-cyclohexane, and 3-methylthiophene-cyclohexane showed that the decrease in mulliken charges (e-) of sulfur atoms facilitated the S-Ag bond interaction between the sulfur atom of thiophenic compounds and active component in the sorbent. In conclusion, to obtain the Ag-based sorbent with good adsorption performance for thiophenic compounds, the carrier should contain a certain content of silicon hydroxyl and the suitable pore structure. During the preparation of SBA-15 and MCM-41 mesoporous materials modified by Ag, the Ag-O-Si bonds are more easily formed when silver ammonia interacts with the silicon hydroxyl group on the surface of the carrier. The suitable pore size can inhibit agglomerate to form metallic Ag during the calcination process. These conclusions will provide theoretical guidance for the preparation of silver-based sorbents for thiophene.

Quantum computational, spectroscopic and molecular docking studies of potent tuberculosis drug 2,6-dihydroxypyridine-4-carboxylic acid and 2‑hydroxy -6-methylpyridine-4-carboxylic acid

This study reports the molecular structure and spectroscopic (FT-IR, FT-Raman, UV–Vis, 1H and 13C NMR) investigations of 2,6-dihydroxypyridine-4-carboxylic acid (HPC) (citrazinic acid) and 2‑hydroxy -6-methylpyridine-4-carboxylic acid (HMPC) molecules. The quantum computational calculations were performed by density functional theory (DFT) method using the B3LYP/ 6–311++G (d,p) basis set. The vibrational wavenumbers and NMR chemical shifts were matched well with the experimental data. The title molecules exhibited two kinds of dimers such as J and H- type dimers. The Mulliken atomic charge distribution for neutral, anionic, and cationic states was performed to predict Fukui function and global softness of the molecules. From the molecular electrostatic potential (MEP) map the reactive sites were identified and the reactivity of the title compounds was examined through the HOMO-LUMO energy gap. Natural Bonding Orbital (NBO) analysis revealed that the presence of stabilization interactions within the title molecules. In addition, the molecular docking studies carried out for title molecules to determine protein ligand interaction to confirm the inhibition activity against Mycobacterium tuberculosis. Additionally, the non-linear optical property was also calculated for title molecules.

Insights into the interaction between NO and char(N) containing different functional forms: Mechanistic, thermodynamic and kinetic studies

Char-bound nitrogen [char(N)] is confirmed to be the real intermediate in heterogeneous reduction during coal combustion. Aiming to have a deep insight into the interaction mechanism between NO and char(N) containing different functional forms of nitrogen, a comprehensive theoretical exploration with density functional theory at M06–2X/6–31G(d,p)//def-TZVP level is performed. The detailed electronic descriptions of char(N) surface based on spin density, Mulliken atomic charge and electrostatic potential exhibit the attack sites and electron donating capability during NO chemisorption in the following order: char(N-5) < char(N-X) < char(N-6). Oxygen surface complex, an intermediate for N2O formation and a catalyst for NO reduction, can weaken the connected CN bond and promote N2 separation. The migration of oxygen atoms to adjacent active sites is thermodynamically conducive to reduction reactions, leading to the preferred pathway of N2 release on char(N-5) and char(N-X) surfaces. Contiguous active sites remaining along char edge are unfavorable for N2O detaching, while beneficial to NO further chemisorption for consecutive reactions, resulting in the great contributions of char(N-5) in reducing NO. The lower energy barriers for NO reduction follow the sequence coincident with the results of electronic property analysis. The kinetically favorable temperatures and activation energies of different char(N) for reducing NO are determined, which is consistent with previous experiments. The theoretical results provide evidences to explain microscopic mechanism of NO-char(N) interaction, making contributions to effectively minimize NOx emissions in the future.

Novel Isoxazolone Based Azo Dyes: Synthesis, Characterization, Computational, Solvatochromic UV-Vis Absorption and Biological Studies

• Novel isoxazolone based azo dyes were synthesised and spectroscopically characterized • Computational study- Frontier molecular orbitals, Mulliken population analysis, Global reactive parameters, Molecular electrostatic potential and Reduced density gradient analysis • Solvatochromic UV-Vis absorption study was carried out • Antimycobacterial and anti-inflammatory efficacy were studied In this research investigation, novel isoxazolone-thiazole based azo dyes ( Io1-Io4 ) were synthesized by a conventional azo coupling reaction at 0-5°C. The structure elucidation was precisely assessed using various spectroscopic techniques like FT-IR, NMR and HRMS. Through computational study, molecular geometry, mulliken atomic charges and global reactive descriptors were investigated to get a better insight into the molecular properties. Molecular electrostatic potential (MEP) and reduced density gradient analysis (RDG) were also examined. The solvatochromic UV-Vis absorption study was performed using different solvents. A diffuse reflectance study was carried out to determine the optical band gap of the synthesized novel dyes ( Io1-Io4) . Biological efficacy towards antimycobacterial and anti-inflammatory activity was examined and the results revealed that, the compounds showed very good antimycobacterial and anti-inflammatory activity.