scholarly journals Corrosion Inhibitive Potentials of some 2H-1-benzopyran-2-one Derivatives- DFT Calculations

2021 ◽  
Vol 11 (6) ◽  
pp. 13968-13981
Keyword(s):  
Charge Distribution ◽  
Metal Surface ◽  
Electrostatic Potential ◽  
Density Functional ◽  
Effective Interaction ◽  
Basis Set ◽  
Mulliken Charge ◽  
Surface Mode ◽  
Adsorption Sites ◽  
Fukui Indices

There is an increased demand for metals and alloys because of their use in household appliances and industrial machines. However, they react with the environment and are consequently prone to loss of strength and durability owing to corrosion. In a bid to eradicate or control this, the use of corrosion inhibitors has been employed. Quantum chemical calculations have been used to predict the corrosion inhibitive potentials of novel molecules and probe into their metals' surface mode of action. Density functional theory was employed here with a polar basis set, 6-31G(d), to investigate the corrosion inhibitive potentials of some 2H-1- benzopyran-2-ones derivatives via their electronic properties, global reactivity descriptors, electrostatic potential maps, and Fukui indices. The energy gaps follow the order: c > e > a > d > b > g > f > h, indicative that compounds f and h would effectively protect metals’ surface against corrosion with the HOMO map essentially delocalized over the benzopyran-2-one moiety and the attached substituents while the LUMO plot shows a delocalization of the lowest vacant molecular orbitals over the entire benzopyran-2-one moiety. The asymmetric charge distribution on the inhibitors from the electrostatic potential maps indicates that each compound possesses reactive adsorption sites for bonding and back-bonding with the metal surface. The Mulliken charge distribution and the Fukui indices reveal that the adsorption of an inhibitor on a metal surface is not only via the heteroatoms like O, Cl, Br, and N. The contribution of carbon atoms as nucleophilic and electrophilic centers ensures effective interaction between a metal surface and the inhibitor and isolates the material from corroding environment.

Electronic, Vibrational, and Structural Study of Polysaccharide Agar-Agar Biopolymer

2021 ◽  
Vol 33 ◽  
pp. 35-46
Author(s):  
Ankita Pandey ◽  
Abhishek Kumar Gupta ◽  
Shivani Gupta ◽  
Sarvesh Kumar Gupta ◽  
Rajesh Kumar Yadav
Keyword(s):  
Charge Distribution ◽  
Molecular Orbital ◽  
Structural Study ◽  
Density Functional ◽  
Vibrational Analysis ◽  
Chemical Properties ◽  
Atomic Charge ◽  
Dft Method ◽  
Basis Set ◽  
Mulliken Charge

Polysaccharide biopolymer Agar-Agar extracted from red algae is a natural and biodegradable polymer. It is a combination of agarose (a neutral and linear polymer, with repeated units of agarobiose) and a heterogeneous mixture of agaropectin (a charged sulfated polymer). In this study, a comparative study of structural vibrational and electrochemical properties of agar-agar biopolymer with two different methods HF (Hartree-Fock) and DFT (Density Functional Theory) using a basis set 631+G (d, p) is performed. The comparative structural study of agar-agar biopolymer by HF and DFT method has been carried out to calculate the stability of the molecule. The thermionic properties and Mulliken charge distribution are analysed to deliver a quantitative study of partial atomic charge distribution. The overall vibrational analysis of primal modes of the biopolymer has been studied using FTIR analysis. Based on highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) composition and energies, various chemical parameters of the biopolymer have been evaluated. The Physico-chemical properties of this polysaccharide show a strong correlation with its optimized structure. Agar-agar has its application in the electrochemical, biotechnological, and pharmaceutical fields, as a stabilizer and gelling material.

Experimental and Theoretical Studies on the Molecular Structure, FT-IR, NMR, HOMO, LUMO, MESP, and Reactivity Descriptors of (E)-1-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one

2020 ◽  
Vol 17 (SpecialIssue1) ◽  
pp. 54-72
Author(s):  
Rahul Ashok Shinde ◽  
Vishnu A shok Adole ◽  
Bapu Sonu Jagdale ◽  
Thansing Bhavsing Pawar
Keyword(s):  
Molecular Structure ◽  
Electrostatic Potential ◽  
Density Functional ◽  
Dft Method ◽  
Basis Set ◽  
Group Symmetry ◽  
Ir Absorption ◽  
Hydrogen Atoms ◽  
Reactivity Descriptors ◽  
Ft Ir

The present research deals with the synthesis, characterization and density functional theory (DFT) study of (E)-1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (DTMPP). For the computational investigation, DFT method at B3LYP/6-311++G(d,p) basis set has been used. Herein, structural properties like molecular structure, bond lengths, and bond angles of the DTMPP have been explored. The all-important examination of the electronic properties; HOMO and LUMO energies were studied by the time-dependent DFT (TD-DFT) method. The experimental and theoretical spectroscopic Investigation on FT-IR, 1HNMR, 13C NMR has been unveiled in the present research. To study the chemical behaviour of the DTMPP, Mulliken atomic charges, molecular electrostatic surface potential, and reactivity descriptors have been explored. The dipole moment of the DTMPP is 1.27 Debye with C1 point group symmetry and -1225.77 a.u. E(B3LYP) energy. The most electropositive carbon and hydrogen atoms in the DTMPP are C14 and H27 respectively. The C1-C6 bond is the longest (1.4089 Å) C=C bond in the DTMPP. The oxygen atom O33 is having short contact interaction with the hydrogen atom H44 with a distance of 3.3258 Å. The molecular electrostatic potential plot predicts the positive electrostatic potential is around hydrogen atoms. The FT-IR assignments were made by comparing the experimental FT-IR absorption peaks with the scaled frequencies obtained using DFT method. Furthermore, some valuable insights on thermochemical data are obtained using the harmonic frequencies at same basis set.

Theoretical study of 11-thiocyanatoundecanoic acid phenylamide derivatives on corrosion inhibition efficiencies

2014 ◽  
Vol 92 (9) ◽  
pp. 876-887 ◽  
Author(s):  
Seda Sagdinc ◽  
Yesim Kara ◽  
Filiz Kayadibi
Keyword(s):  
Density Functional ◽  
Corrosion Inhibitors ◽  
Energy Gap ◽  
Basis Set ◽  
Inhibitor Molecule ◽  
Functional Theory ◽  
Fukui Functions ◽  
Reactivity Descriptors ◽  
Hartree Fock ◽  
Adsorption Sites

Ab initio Hartree–Fock (HF) and Density Functional Theory (DFT) B3LYP methods with the 6-311G(d,p) basis set were applied to the three 11-thiocyanatoundecanoic acid phenylamide derivatives as corrosion inhibitors. Inhibition efficiency obtained experimentally followed the following order: N-(4-methoxyphenyl)-11-thiocyanatoundecanamide (N3MPTUA) > N-phenyl-11-thiocyanatoundecanamide (NPTUA) > N-(3-nitrophenyl)-11-thiocyanatoundecanamide (N3NPTUA). The molecular parameters most relevant to their potential action as corrosion inhibitors have been calculated in the neutral and protonated forms: EHOMO, ELUMO, energy gap (ΔE), dipole moment (μD), electronegativity (χ), global hardness (η), and the fraction of electrons transferred from the inhibitor molecule to the metallic atom (ΔN). The results of most of the global reactivity descriptors show that the experimental and theoretical studies agree well, and confirm that N3MPTUA is a better inhibitor than NPTUA or N3NPTUA. In addition, the local reactivity, analyzed through Fukui functions, show that the oxygen and nitrogen atoms will be the main adsorption sites.

scholarly journals Density functional theory calculations and Hirshfeld surface analysis of propyl-para-hydroxybenzoate (PHB) for optoelectronic application

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
V. Mohankumar ◽  
N. Karunagaran ◽  
M. Senthil Pandian ◽  
P. Ramasamy
Keyword(s):  
Charge Transfer ◽  
Surface Analysis ◽  
Density Functional ◽  
Hirshfeld Surface ◽  
Basis Set ◽  
Hirshfeld Surface Analysis ◽  
Frontier Molecular Orbital ◽  
Mulliken Charge ◽  
Charge Analysis ◽  
Orbital Analysis

AbstractThe geometries, electrostatic potential, Mulliken charge analysis, Natural Bond Orbital analysis and polarizabilities of propyl-para-hydroxybenzoate were calculated using B3LYP functional with 6-311++G(d,p) basis set. The calculated geometries are well matched with the experimental values. The Mullliken atomic charge analysis shows that the eventual charges are contained in the molecule. The NBO analysis explains the intramolecular charge transfer in the PHB molecule. The bonding features of the molecule were analyzed with the aid of Hirshfeld surface analysis. The frontier molecular orbital analysis showed the charge transfer obtained within the molecule. The calculated hyperpolarizability of the PHB molecule was 6.977E−30 esu and it was 8.9 times that of standard urea molecule.

scholarly journals Theoretical Evaluation on The Interaction Between Triglycerides and Methylxanthines Using Density Functional Theory B3LYP/6-31G(d,p) and Molecular Electrostatic Potential

2020 ◽  
Vol 33 (1) ◽  
pp. 171-178
Author(s):  
N.F.M. Azmi ◽  
R. Ali ◽  
A.A. Azmi ◽  
M.Z.H. Rozaini ◽  
K.H.K. Bulat ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Electrostatic Potential ◽  
Density Functional ◽  
Molecular Electrostatic Potential ◽  
Basis Set ◽  
Individual Species ◽  
Interaction Energies ◽  
Binding Interaction ◽  
Functional Theory

The binding, interaction and distortion energies between the main triglycerides, palmitic-oleic-stearic (POS) in cocoa butter versus palmitic-oleic-palmitic (POP) in refined, bleached and deodorized (RBD) palm oil with cocoa′s methylxanthines (caffeine, theobromine, and theophylline) during the production of chocolate were theoretically studied and reported. The quantum mechanical software package of Gaussian09 at the theoretical level of density functional theory B3LYP/6-31G(d,p) was employed for all calculations, optimization, and basis set superposition errors (BSSE). Geometry optimizations were carried out to the minimum potential energy of individual species and binary complexes formed between the triglycerides, methylxanthines and polyphenols. The interaction energies for the optimized complexes were then corrected for the BSSE using the counterpoise method of Boys and Bernardi. The results revealed that the binding energy and interaction energy between methylxanthine components in cocoa powder with triglycerides were almost of the same magnitude (13.6-14.5 and 3.4-3.7 kJ/mol, respectively), except for the binary complex of POS-caffeine (25.1 and 10.7 kJ/mol, respectively). Based on the molecular geometry results, the hydrogen bond length and angle correlated well with the interaction energies. Meanwhile, the POS-caffeine complex with two higher and almost linear bond angles showed higher binding and interaction energies as compared to the other methylxanthines. Therefore, a donor-acceptor analysis showed that the hydrogen bond strength was proven using the molecular electrostatic potential (MEP), which resulted in parallel outcomes. The research results were believed to be one of the factors that contributed to the rheological behaviour and sensory perception of cocoa products, especially chocolate.

Influence of H, H2, O and O2 on Armchair SiGe Nanotubes: A Theoretical Study

2016 ◽  
Vol 16 (4) ◽  
pp. 3447-3456
Author(s):  
Prabath Wanaguru ◽  
Asok K Ray ◽  
Qiming Zhang
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Defect Density ◽  
Basis Set ◽  
Hybrid Functional ◽  
Lumo Energy ◽  
Adsorption Sites ◽  
The Difference ◽  
Controlled Adsorption

A systematic, hybrid density functional theory study of interaction between SiGe nanotubes (SiGeNTs) and X (X = H, O, H2 and O2) have been performed using the hybrid functional B3LYP and an all electron 3-21G* basis set implemented in GAUSSIAN 09 suite of software. All possible internal and external adsorption sites were considered, and it was found that H prefers to move onto top of an atom site while O prefers to incorporate into NT wall by breaking the bonds. Adsorption energies for H is ∼2.0 eV and for O it is ∼5.0 eV. Controlled adsorption of atomic H and several molecular O give rises to defect density states in the frontier orbital region. H rich adsorptions predict the difference between highest occupied molecular orbital (HOMO) energy and the lowest unoccupied molecular orbital (LUMO) energy increase while O rich adsorptions predict the decrease in HOMO-LUMO energy gap. O and O2 adsorptions predict definite ionic bonding character while H atomic adsorptions predict covalent bonding. H2 is very neutral towards the adsorption into SiGeNTs and clearly shows the physisorption adsorption. Considering the all adsorptions, the adsorptions happened within the Si vicinity of the SiGeNT shows the most stable and preferred adsorption region.

Intermolecular interactions, charge-density distribution and the electrostatic properties of pyrazinamide anti-TB drug molecule: an experimental and theoretical charge-density study

2014 ◽  
Vol 70 (3) ◽  
pp. 568-579 ◽  
Author(s):  
Gnanasekaran Rajalakshmi ◽  
Venkatesha R. Hathwar ◽  
Poomani Kumaradhas
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Intermolecular Interactions ◽  
Electrostatic Potential ◽  
Density Functional ◽  
Direct Methods ◽  
Hirshfeld Surface ◽  
Basis Set ◽  
Total Electron Density ◽  
Total Electron

An experimental charge-density analysis of pyrazinamide (a first line antitubercular drug) was performed using high-resolution X-ray diffraction data [(sin θ/λ)max= 1.1 Å−1] measured at 100 (2) K. The structure was solved by direct methods usingSHELXS97 and refined bySHELXL97. The total electron density of the pyrazinamide molecule was modeled using the Hansen–Coppens multipole formalism implemented in theXDsoftware. The topological properties of electron density determined from the experiment were compared with the theoretical results obtained fromCRYSTAL09at the B3LYP/6-31G** level of theory. The crystal structure was stabilized by N—H...N and N—H...O hydrogen bonds, in which the N3—H3B...N1 and N3—H3A...O1 interactions form two types of dimers in the crystal. Hirshfeld surface analysis was carried out to analyze the intermolecular interactions. The fingerprint plot reveals that the N...H and O...H hydrogen-bonding interactions contribute 26.1 and 18.4%, respectively, of the total Hirshfeld surface. The lattice energy of the molecule was calculated using density functional theory (B3LYP) methods with the 6-31G** basis set. The molecular electrostatic potential of the pyrazinamide molecule exhibits extended electronegative regions around O1, N1 and N2. The existence of a negative electrostatic potential (ESP) region just above the upper and lower surfaces of the pyrazine ring confirm the π-electron cloud.

Quantum Computational, Spectroscopic and Molecular Docking Studies on N-(4-Hydroxyphenyl)picolinamide

2021 ◽  
Vol 6 (3) ◽  
pp. 186-203
Author(s):  
Meenakshi Singh ◽  
Mukesh Kumar ◽  
Neha Singh ◽  
Shikha Sharma ◽  
Neha Agarwal ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Electrostatic Potential ◽  
Density Functional ◽  
Molecular Geometry ◽  
Energy Difference ◽  
Docking Studies ◽  
Basis Set ◽  
Fukui Functions ◽  
Homo And Lumo ◽  
Gibb’S Free Energy

In this work, the quantum computations of newly synthesized N-(4-hydroxyphenyl)picolinamide (4-HPP) is focused. Density functional theory (DFT) was used to perform the quantum calculations. The optimized molecular geometry was obtained using the B3LYP and MP2 methods employing 6-311++G(d,p) basis set, which served as the foundation for all subsequent calculations. The experimental data was compared with the calculated vibrational frequencies and NMR spectra. With the use of the molecular electrostatic potential surface (MEP) and the Fukui functions, the charge distribution, reactive regions and electrostatic potential were displayed. The chemical activity of the 4-HPP was evaluated by the energy difference between HOMO and LUMO. For better understanding of the intermolecular charge transfer (ICT), natural bond order analysis (NBO) was used. At various temperatures, thermodynamic parameters such as Gibb’s free energy, enthalpy and entropy were determined. The electrophilicity index was used to portray the molecule’s bioactivity and molecular docking was used to show the interaction between the ligand and the protein. The nature of the molecule was determined by drug similarity when expecting its application for medical purposes.

Spectroscopic investigation, HOMO–LUMO energies, natural bond orbital (NBO) analysis and thermodynamic properties of two-armed macroinitiator containing coumarin with DFT quantum chemical calculations

2016 ◽  
Vol 94 (6) ◽  
pp. 583-593 ◽  
Author(s):  
Feride Akman
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Electrostatic Potential ◽  
Density Functional ◽  
Natural Bond Orbital ◽  
Dft Method ◽  
Basis Set ◽  
Orbital Method ◽  
Functional Theory ◽  
Homo Lumo

In the present work, two-armed macroinitiator containing coumarin were synthesized, characterized by Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance techniques and investigated theoretically using density functional theory (DFT) calculations. The molecular geometry, fundamental vibrational frequencies, atomic charges obtained from atomic polar tensors and Mulliken were analyzed by means of structure optimizations based on the DFT method with 6-31G+(d, p) as a basis set. The 1H chemical shifts were calculated by the gauge-including atomic orbital method and compared with available experimental data. The electronic properties, such as highest occupied molecular orbital – lowest unoccupied molecular orbital (HOMO–LUMO) energies, electron affinity, electronegativity, ionization energy, hardness, chemical potential, global softness, and global electrophilicity were calculated by using the DFT method. The electrostatic potential and molecular electrostatic potential surfaces were performed to predict the reactive sites of the two-armed macroinitiator. The energy difference between acceptor and donor and stabilization energy were determined using natural bond orbital analysis. The results show that the occurrence of intramolecular charge transfers within the polymer. Time-dependent density functional theory calculations of visible spectra were analyzed at different solvents. Finally, thermodynamic functions, such as enthalpy, heat capacity, and entropy, of the two-armed macroinitiator at different temperatures were calculated and the relationship with temperature was investigated.

Effect of external electric field on the adsorption of ethylene oxide on pristine and Al-doped coronenes: A DFT study

2018 ◽  
Vol 17 (05) ◽  
pp. 1850032 ◽  
Author(s):  
Tooba Afshari ◽  
Mohsen Mohsennia
Keyword(s):  
Ethylene Oxide ◽  
Electric Fields ◽  
Electronic Structures ◽  
Density Functional ◽  
Molecular Electrostatic Potential ◽  
Band Gap Energy ◽  
Basis Set ◽  
Mulliken Charge ◽  
Functional Theory ◽  
Energy Formula

The adsorption interactions between ethylene oxide (EO) molecule and pristine and aluminum-doped coronene (Al-coronene) were studied in the presence and absence of perpendicular external electric fields (EFs) with strengths [Formula: see text], [Formula: see text] and [Formula: see text] a.u. using density functional theory (DFT) calculations. The geometry optimizations and adsorption calculations were carried out by employing 6-31[Formula: see text]G** basis set. The changes in geometric and electronic structures after the adsorption were investigated to characterize the sensitivity of pristine and Al-coronene toward EO molecules. For all the studied systems, adsorption energies ([Formula: see text], band gap energy ([Formula: see text], Mulliken charge transfer, molecular electrostatic potential (MEP) and density of electron state (DOS) were calculated and discussed. According to the obtained results, the high impact of the applied EFs on the adsorption characteristics of EO molecules on the pristine and Al-doped coronenes showed that applying EF is a good strategy for enhancing the EO adsorption capability of the pristine and Al-doped coronenes, improving the potential application of coronene-based sensors for detection of EO in trace amounts.

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