Overlap Population Density Of States Research Articles

DFT quantum chemical calculations (Fukui functions, NLO, TDOS, OPDOS, DNA/ECT) on 4-(dec-2yn-1-yloxy)phthalonitrile

In this study, structural and electronic properties of 4-(dec-2yn-1-yloxy)phthalonitrile were analyzed theoretically. The optimized structure in the gas phase of the title compound was achieved by density functional theory (DFT) method with the B3LYP hybrid functional using 6-31G (d,p) basis set. Then, IR, 1H-NMR, 13C-NMR spectroscopic properties of the title molecule were calculated and compared with the corresponding experimentally ones. Besides these, the molecular electrostatic potential (MEP) surface, frontier molecular orbitals (FMO), chemical activity, Fukui function analysis, nonlinear optical properties (NLO) in different solvent environments, total (TDOS), partial (PDOS) and overlap population density of state (OPDOS) diagrams were offered. Finally, the interactions between the title molecule with adenine, cytosine, thymine and guanine which are DNA bases were investigated by using the electrophilicity-based charge transfer (ECT) method and charge transfer (ΔN). According to NLO calculations, the value of the first hyperpolarizability of the title compound in the gas phase was found nearly twenty two times more than that of urea.

TDOS/PDOS/OPDOS, reduced density gradient (RDG) and molecular docking studies of [3-(3-bromophenyl)-cis-4,5-dihydroisoxazole-4,5-diyl]bis(methylene) diacetate

Due to the wide range of biological activity, 4,5-dihydroisoxazole compounds form an important family of five-membered heterocycles containing an oxygen atom and a nitrogen atom in the adjacent position. Therefore, [3- (3-bromophenyl) -cis-4,5-dihydroisoxazol-4,5-yl] bis (methylene) diacetate [BDBD] compound, which is a derivative of 4,5-dihydroisoxazole, was investigated in this study. The partial density of state (PDOS), the overlap population density of state (OPDOS) and total density of state (TDOS) of functional groups of the [BDBD] compound were theoretically evaluated using the DFT / B3LYP / 6-311G (d, p) method. Reduced density gradient (RDG) was also given to study the weak interaction, strong attraction, and strong repulsion interactions of the studied molecule. The PASS (Prediction of Activity Spectra) analysis predicts the carcinogenic activities with probability to be active value of 0.273 for the studied molecule. The antibacterial and anti-inflammatory activities of the [BDBD] compound against various the HIV-1 protease (1HSG), GyrB ATPase (3U2D), and VEGFR-2 kinase enzyme (4AG8) proteins were studied using molecular docking. The binding energies of 1HSG, 3U2D, and 4AG8 target proteins with [BDBD] ligand were calculated to be -6.11, -4.54, and -4.80 kcal/mol, respectively. Results were interpreted by comparing with the literature.

Theoretical studies on the catalytic hydrogenation of carbon dioxide by 3d transition metals single-atom catalyst supported on covalent triazine frameworks

• The co-adsorption configuration of hydrogen and CO 2 on the unsaturated coordination single-atom catalysts (SACs) gives it a unique selectivity for CO 2 hydrogenation to formic acid. • A ‘volcano’ plot was established between the 3d-orbital electron number and barrier energy, in which Ni appeared at the summit. • Part of the overlap population density of states (OPDOS) of Ni and H atom is located in unoccupied orbitals, resulting in a weak Ni H bond. • Inert intermediates lead to low activity of Sc, Ti, V. The catalytic conversion of carbon dioxide (CO 2 ) into value-added products is a significant emission reduction method. Among numerous catalysts, single-atom catalysts (SACs) show great potential in CO 2 hydrogenation. However, it is difficult to predict the CO 2 hydrogenation products because the SACs consisting of the same metal and different supports commonly show various catalytic selectivity. Here we study the catalytic mechanism of the CO 2 hydrogenation process catalyzed by the SAC with 3d transition metals. The metal atoms are anchored on the covalent triazine frameworks (CTFs). We find the correlation between adsorption configuration and the selectivity of the CO 2 hydrogenation. The coadsorption configuration of the H atom and CO 2 molecule is favorable to forming the C H bond in formate. A volcano relation based on activation barrier and 3d-orbital electron numbers was obtained. We found that the catalyst with Ni metal has the lowest activation barrier. We also explained the low catalytic activity of Sc, Ti, and V metals due to the inert intermediates occupying the active sites. This work may be helpful to design highly selective and highly active catalysts in CO 2 hydrogenation.

Vibrational, spectroscopic, chemical reactivity, molecular docking and in vitro anticancer activity studies against A549 lung cancer cell lines of 5‐Bromo‐indole‐3‐carboxaldehyde

Spectroscopic investigations are performed for 5-Bromo-1H-indole-carboxaldehyde by using experimental (FT-IR, FT-Raman) and theoretical (DFT) calculations. Vibrational assignments of the fundamental modes were assigned on the basis of Potential energy distribution (PED) calculations. Electron Localization Function (ELF) and Local Orbital Localizer (LOL) studies were performed to visualize the electron delocalization in the molecule. Frontier molecular orbitals (FMOs) and related molecular properties were computed. The electron-hole distribution of the molecule was also computed using Multiwfn 3.3.9 software to predict the charge transfer within the molecule. The total and partial density of states (TDOS and PDOS) and also the overlap population density of states (OPDOS) spectra were simulated. UV-Vis spectrum of the compound was also recorded. The reactive sites of the compound were studied from the MEP and Fukui function analysis. The charge delocalization and stability of the title molecule were investigated using natural bond orbital (NBO) analysis. The lung cancer activity of the title compound against p53 tumor suppressor proteins was studied using molecular docking analysis. The in-vitro cytotoxic activity of the molecule against human pulmonary lung cancer cell lines (A549) was determined by MTT assay.

Efficient tuning of triphenylamine-based donor materials for high-efficiency organic solar cells

Small molecular donors (SMDs) manifest promising photovoltaic performance and rapid progress in solar cells community. Herein, we investigate high-performance triphenylamine (TPA) small molecular donors for solar cells applications. We specifically designed four donor molecules (D1–D4) with a strong donor moiety of triphenylamine (TPA) linked to four different end-capped units. The structure-property relationship and effects of end-capped units on D1-D4 are theoretically calculated and compared with reference molecule R. DFT and TD-DFT approach have been employed and assessments of photophysical characteristics, frontier molecular orbitals (FMOs), reorganization energies, density of state (DOS) and overlap population density of state (OPDOS), open-circuit voltages (Voc), transition density matrix (TDMs), surfaces and charge transfer analysis were conducted. In comparison to synthesized reference molecule R, designed D1-D4 molecules show significant and comparable optoelectronic properties. The D3 designed molecule is proven as the best candidate for solar cells applications than all other due to its promising photovoltaic properties involving the lowest band gap (3.329 eV) and excitation energy (3.094 eV), small reorganization energies for electron (λe = 0.110 eV) and hole (λh = 0.055 eV), low binding energy (Eb = 0.221 eV), highest λmax values 396.69 nm, 400.63 nm both in gas and solvent form, respectively. This theoretical designed model confirms that the end-capped unit modifications proves an efficient alternative solution in achieving the desired optoelectronic properties. Therefore, D1-D4 designed molecules are outstanding and highly recommended to experimentalists for developments of highly efficient solar cells devices in future.

Synthesis, spectra, electronic structure, molecular docking and cytotoxicity investigation on 2-(piperidin-1-ylmethyl)-isoindoline-1,3-dione – A Mannich base system

A Mannich base molecule of 2-(piperidin-1-ylmethyl)isoindoline-1,3-dione (PPF) has been synthesized using Mannich base condensation reaction. The molecular geometry of PPF molecule was optimized by B3LYP/6-311G(d,p) basis set. The vibrational frequencies have been assigned with the aid of normal coordinate analysis. Total energy distributions (TED) were used to explain each vibrational wavenumber assignments of a molecule. The 1H and 13C NMR spectroscopic analyses were predicted by using gauge independent atomic orbital (GIAO) method. The thermal stability was determined by applying the thermo gravimetric/differential scanning calorimetry (TG/DSC) studies. The HOMO-LUMO energies, population density of states (PDOS), overlap population density of states (OPDOS), reduced density gradient (RDG), Mulliken atomic charges and molecular electrostatic potential (MEP) surface were plotted to investigate the van der Waals, attraction, repulsion, non-covalent and covalent interactions of the compound. The natural bond orbital (NBO) charge analysis was used in explaining the intermolecular charge transfer and resonance stabilization energy of molecule. Besides, the molecular docking studies have been performed. The cytotoxic activity of the PPF molecule has been resolved.

Identifying the active sites of carbonaceous surface for the adsorption of gaseous arsenic trioxide: A theoretical study

Arsenic pollutants released from coal-fired power plant caused great harm to human health and the environment due to its high toxicity and bioaccumulation. Gaseous As2O3 is one of the main arsenic pollutants in coal power plant flue gas. The literature suggests that As2O3 can be effectively removed by the unburned carbon. However, the active sites of the unburned carbon for As2O3 adsorption has not been clearly identified, which greatly hinders the development of effective adsorbents. To reveal the active sites of As2O3 adsorption, the adsorption characteristic of As2O3 on different carbonaceous surfaces were systematically investigated through density functional theory calculations. In this work, the adsorption mechanism of As2O3 was studied through Mayer bond order, overlap population Density-of-states (OPDOS), and Atomic Dipole Moment Corrected Hirshfeld (ADCH) charge analysis. The adsorption of As2O3 on defective surfaces is associated with stable chemisorption, and surface defects can significantly improve the adsorption energy of As2O3. This theoretical study clarifies the adsorption active sites in carbonaceous surfaces and provide theoretical guidance for the development of efficient adsorbents for As2O3.

Spectroscopic, quantum chemical, molecular docking and in vitro anticancer activity studies on 5-Methoxyindole-3-carboxaldehyde

The FT-IR and FT-Raman spectra of 5-Methoxyindole-3-carboxaldehyde (MICA) molecule were recorded. The experimental and theoretical vibrational wavenumbers were assigned and compared. The non-linear optical (NLO) activity of the molecule was confirmed using second harmonic generation test and compared with theoretical result. The natural bond orbital (NBO) analysis was carried out to evaluate the intramolecular stabilization interactions of the molecule, which are responsible for the bio-activity of the molecule. The molecular electrostatic potential surface, frontier molecular orbitals and Fukui function analysis reveal the charge transfer interactions in the molecule. The total density of states (TDOS), partial density of states (PDOS), and overlap population density of states (OPDOS) studies were performed in order to visualize the molecular orbital contributions of the molecule. The molecular docking analysis was carried out to explore the inhibitory nature of the molecule, which indicates that molecule can acts as a novel inhibitor of lung cancer causing VEGF receptor. In addition, the in vitro cytotoxicity of the molecule confirms the anticancer activity against the human pulmonary epithelial lung cancer cell lines (A549). Hence, the present investigations pave the way for the development of lung cancer drugs.

Synthesis, Characterization, Crystal Structure, and DFT Study of 4-Bromo-2-(4,6-Dichloro-Phenylimino)-Phenol

The experimental crystal structure of a Schiff base compound 4-bromo-2-(4,6-dichloro-phenylimino)-phenol 1 is determined by single crystal X-ray diffraction and also characterized by FT-IR and 1H NMR spectroscopy. The electronic structure in the gas phase is studied by density functional theory (DFT) calculations.The theoretical results have good agreement with the data obtained from the crystallographic analysis. In addition, theoretical configurations which refer to the title compound are relaxed and studied in terms of the combined analysis of HOMO-LUMO energy gap, total density of states (DOS), partial density of state (PDOS), overlap population density of state (OPDOS), molecular electrostatic potential (MEP), NMR spectra, and harmonic vibrational frequencies.

Synthesis, characterization, crystal structure, and DFT study of 4-bromo-2-(4,6-dichloro-phenylimino)-phenol

The experimental crystal structure of a Schiff base compound 4-bromo-2-(4,6-dichloro-phenyl­imino)-phenol 1 is determined by single crystal X-ray diffraction and also characterized by FT-IR and 1H NMR spectroscopy. The electronic structure in the gas phase is studied by density functional theory (DFT) calculations.The theoretical results have good agreement with the data obtained from the crystallographic analysis. In addition, theoretical configurations which refer to the title compound are relaxed and studied in terms of the combined analysis of HOMO-LUMO energy gap, total density of states (DOS), partial density of state (PDOS), overlap population density of state (OPDOS), molecular electrostatic potential (MEP), NMR spectra, and harmonic vibrational frequencies.

Influence of nitrogen doping in sumanene framework toward hydrogen storage: A computational study

Two conditions are important to obtain appropriate substances for hydrogen storage; high surface area and fitting binding energy (BE). Doping is a key strategy that improves BE. We investigated hydrogen adsorption onto twenty six nitrogen disubstituted isomers of sumanene (C19N2H12) by MP2/6–311++G(d,p)//B3LYP/6–31+G(d) and M06-2X/6–31+G(d) levels of theory. Effect of nitrogen doping in different positions of sumanene was checked. To obtain better BE, basis set superposition error (BSSE) and zero point energy (ZPE) corrections were used. Anticipating of adsorption sites and extra details about adsorption process was done by molecular electrostatic potential (MEP) surfaces. Various types of density of state (DOS) diagrams such as total DOS (TDOS), projected DOS (PDOS) and overlap population DOS (OPDOS) and natural bond orbital (NBO) analysis were used to find better insight on the adsorption properties. In addition of temperature depending of the BE, HOMO-LUMO gap (HLG), dipole moment, reactivity and stability, bowl depth and natural population analysis (NPA) of the isomers were studied. A physisorption mechanism for adsorption was proposed and a trivial change was seen. Place of nitrogen atoms in sumanene frame causes to binding energy increases or decreases compared with pristine sumanene. The best and the worst isomers and category of isomers were suggested.

Effect of boron doping in sumanene frame toward hydrogen physisorption: A theoretical study

Because of carbon-based materials have shown excellent results for the adsorption of hydrogen as an energy source, in this study, adsorption properties of 26 boron disubstituted sumanene isomers were investigated using MP2/6-311++G(d,p)//B3LYP/6-31+G(d) level of theory. The influence of sumanene modifications on its adsorption properties towards the hydrogen molecule was evaluated and zero point energy (ZPE) and basis set superposition error (BSSE) corrections were applied to calculate interaction energies (IE). Molecular electrostatic potential (MEP) surfaces were also employed to better understanding the adsorption sites and additional details about adsorption. The adsorption properties were discussed by using density of states (DOS), projected density of states (PDOS), overlap population density of states (OPDOS) and natural bond orbital (NBO) analysis. Stability and reactivity, natural population analysis (NPA), dipole moment, HOMO–LUMO gap (HLG) and bowl depth of the isomers were discussed and temperature effects on the interaction energy were evaluated. The results indicate a physisorption mechanism and insignificant perturbation of isomers after adsorption. Also, respect to position of boron atoms in frame of sumanene, interaction energy increases or decreases in comparison with pristine sumanene. The best and the worst isomers and the best and the worst classes of isomers were proposed for future experimental studies.

Spectroscopic studies on 9H-carbazole-9-(4-phenyl) boronic acid pinacol ester by DFT method

9H-Carbazole-9-(4-phenyl) boronic acid pinacol ester (9-CPBAPE) molecule was investigated by FT-IR, Raman, UV–vis, 1H and 13C NMR spectra. FT-IR, FT-Raman and dispersive Raman spectra were recorded in the solid phase. 1H, 13C NMR and UV–vis spectra were recorded in dimethyl sulfoxide (DMSO) solution. The results of theoretical calculations for the spectra of the title molecule were compared with the experimental spectra. The highest occupied molecular orbital (HOMO) the lowest unoccupied molecular orbital (LUMO) and molecular electrostatic potential (MEP) analyses were performed. The theoretical calculations for the molecular structure and spectroscopic studies were performed with DFT (B3LYP) and 6-311G (d,p) basis set calculations using the Gaussian 09 program. The total (TDOS), partial (PDOS) density of state and overlap population density of state (OPDOS) diagrams analyses were performed using GaussSum 2.2 program.

Systematic analysis of structural and spectroscopic properties of neptunimine (HN=NpH2) and plutonimine (HN=PuH2).

The structures, stabilities, nature of bonding, and spectroscopic properties of the new actinide imine molecules, neptunimine (HN=NpH2) and plutonimine (HN=PuH2), in the gas phase have been systematically explored at different levels of theory. Our calculation indicates that HN=AnH2 (An=Np, Pu) should be nonplanar and have a quartet ([Formula: see text]) and quintet ([Formula: see text]) ground state, respectively. The nature of the chemical bonding in these molecules were investigated by employing topological methods including electron localization function (ELF), atoms in molecules (AIM) as well as natural bond orbital analysis (NBO). The results showed that these actinide complexes possess relatively strong An=N multiple bonds between the An 6d-5f hybrid orbitals with N 2s-2p orbitals. The charge decomposition analysis (CDA) diagram demonstrated that the transition of electrons mainly happened inside the AnH2 of HN=AnH2. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were implemented. The IR and Raman spectra were theoretically simulated as a convenient way to confirm the existence of the actinide imine complexes in further experiments.

Quantum Mechanical Study of Substituent Dependence on the Structure, Spectroscopic (13C, 1H NMR and UV), NBO, Hyperpolarizability and HOMOLUMO Analysis of Ru(NHC)2Cl2(CH‐p‐C6H4X) Complexes

AbstractIn this work, we have explored the structural, electronic properties, 13C and 1H NMR parameters and first hyperpolarizability of Ru(NHC)2Cl2(CH‐p‐C6H4X) complexes (XH, F, Cl, Me, NH2, OH, CN, NO2, CHO, COOH) by mpw1pw91 quantum method. The X‐substituent effect on structural parameters, frontier orbital energies, spectroscopic (1H and 13C NMR, UV) of complex was carried out. The results indicate that the substituent has played a significant role on the structures and properties of complex. 1H and 13C NMR chemical shifts were calculated by using the gauge‐invariant atomic orbital (GIAO) method. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were exhibited. In analyzing the bonding characteristics of this structure, Ru‐Ccarbene and Ru‐CNHC bonds were identified and characterized in details by Natural bond orbital (NBO) analysis.

Quantum chemical calculation (electronic and topologic) and experimental (FT-IR, FT-Raman and UV) analysis of isonicotinic acid N-oxide

In this work, the molecular conformation, vibrational and electronic analysis of isonicotinic acid N-oxide (iso-NANO) were presented in the ground state using experimental techniques (FT-IR, FT-Raman and UV) and density functional theory (DFT) employing B3LYP exchange correlation with the 6-311++G(d,p) basis set. The geometry optimization and energies associated possible two conformers (Rot-I and Rot-II) were computed. The vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The obtained structures were analyzed with the Atoms in Molecules (AIMs) methodology. The computational results diagnose the most stable conformer of iso-NANO as the Rot-I form. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (OPDOS) diagrams analysis for the most stable conformer (Rot-I) were calculated using the same method. Thermodynamic properties (heat capacity, entropy and enthalpy) of the title compound at different temperatures were calculated. As a result, the optimized geometry and calculated spectroscopic data show a good agreement with the experimental results.

Theoretical Study of Hydrogen Adsorption on Ru-Decorated (8,0) Single-Walled Carbon Nanotube

Hydrogen adsorption on Ru-decorated (8,0) zigzag single-walled carbon nanotube (SWCNT) was studied using density functional theory (DFT). Several decoration sites on the CNT surface were investigated before atomic or molecular hydrogen adsorption. The most stable location for a single Ru atom is above the hollow site, with an adsorption energy of Eads(Ru) = −2.133 eV. Ru decoration increases hydrogen adsorption energy nearly 46% compared to pristine CNT. When a hydrogen molecule is considered on Ru/SWCNT its adsorption is dissociative with an Eads(H2) = −0.697 eV. The Ru-decorated SWCNT systems exhibit magnetic properties. Density of states (DOS) and overlap population density of states (OPDOS) were computed in order to study the evolution of the chemical bonding. C–C bonds interact with Ru and are weakened after adsorption. Strong Ru–H bonds are formed during hydrogen adsorption process at expenses of C–Ru bonds. The mains interactions include the Ru 5pz and 4dz2 and C 2pz bands.

FT-IR, FT-Raman, dispersive Raman, NMR spectroscopic studies and NBO analysis of 2-Bromo-1H-Benzimidazol by density functional method

In this study, geometrical optimization, FT-IR (4000–400cm−1), FT-Raman (4000–40cm−1), dispersive Raman (4000–40cm−1) spectroscopic analysis, electronic structure and 1H and 13C nuclear magnetic resonance (NMR) studies of 2-Bromo-1H-Benzimidazol (abbreviated as 2Br1HB) were undertaken by utilizing DFT/B3LYP with 6-311+G(d,p) basis set. The results of the calculations were applied to simulate spectra of the title compound, which show good agreement with observed spectra. Complete vibrational assignments, analysis and correlations of the fundamental modes for 2Br1HB compound were carried out. Stability of the molecule arising from hyperconjugative interactions, charge delocalization was analyzed using natural bond orbital (NBO) analysis. The molecule orbital contributions were studied by using the total density of states (TDOS), partial density of states (PDOS), and overlap population density of states (OPDOS). The electronic properties like HOMO–LUMO energies and molecular electrostatic potential (MEP) analysis were reported. The calculated HOMO and LUMO energies shows that charge transfer interactions take place within the molecule. Mulliken population analysis on atomic charges was also calculated. Good correlation between the experimental 1H and 13C NMR chemical shifts in DMSO solution and calculated gauge-including atomic orbital (GIAO) shielding tensors were found.

Experimental (FT-IR, FT-Raman, UV and NMR) and quantum chemical studies on molecular structure, spectroscopic analysis, NLO, NBO and reactivity descriptors of 3,5-Difluoroaniline

Comprehensive investigation of geometrical and electronic structure in ground as well as the first excited state of 3,5-Difluoroaniline (C6H5NF2) was carried out. The experimentally observed spectral data (FT-TR and FT-Raman) of the title compound was compared with the spectral data obtained by DFT/B3LYP method using 6-311++G(d,p) basis set. The molecular properties like dipole moment, polarizability, first static hyperpolarizability, molecular electrostatic potential surface (MEPs), and contour map were calculated to get a better insight of the properties of the title molecule. Natural bond orbital (NBO) analysis was applied to study stability of the molecule arising from charge delocalization. UV–Vis spectrum of the title compound was also recorded and the electronic properties, such as Frontier orbitals and band gap energies were measured by TD-DFT approach. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. Global and local reactivity descriptors were computed to predict reactivity and reactive sites on the molecule. 1H and 13C NMR spectra by using gauge including atomic orbital (GIAO) method of studied compound were compared with experimental data obtained. Moreover, the thermodynamic properties were evaluated.

Structural investigation of a self-assembled monolayer material 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid for organic light-emitting devices

The molecular structure and vibrations of 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid (MePIFA) were investigated by infrared and Raman spectroscopies, UV–Vis, 1H and 13C NMR spectroscopic techniques and NBO analysis. FT-IR, FT-Raman and dispersive Raman spectra were recorded in the solid phase. 1H and 13C NMR spectra and UV–Vis spectrum were recorded in DMSO solution. HOMO–LUMO analysis and molecular electrostatic potential (MEP) analysis were performed. The theoretical calculations for the molecular structure and spectroscopies were performed with DFT (B3LYP) and 6-311G(d,p) basis set calculations using the Gaussian 09 program. After the geometry of the molecule was optimized, vibration wavenumbers and fundamental vibration wavenumbers were assigned on the basis of the potential energy distribution (PED) of the vibrational modes calculated with VEDA 4 program. The total (TDOS), partial (PDOS) density of state and overlap population density of state (OPDOS) diagrams analysis were made using GaussSum 2.2 program. The results of theoretical calculations for the spectra of the title compound were compared with the observed spectra.