scholarly journals Structure, Vibrations, Molecular Orbitals, Reactivity Properties of 3-Trifluoromethylphenylchloroformate by FT-IR, FT-Raman, FT-NMR and DFT Studies

2019 ◽  
Vol 31 (8) ◽  
pp. 1737-1747
Author(s):  
V. Arjunan ◽  
S. Senthilkumari ◽  
S. Mohan
Keyword(s):  
Energy Gap ◽  
Chemical Shifts ◽  
Structural Parameters ◽  
Atomic Orbital ◽  
Molecular Orbitals ◽  
Basis Sets ◽  
Nucleophilic Attack ◽  
Orbital Energy ◽  
Total Electron Density ◽  
Total Electron

The geometry of 3-trifluoromethylphenylchloroformate (FMPCF) was optimized with B3LYP method using 6–311++G** and cc–pVTZ basis sets. The molecular structural parameters and thermodynamic properties of the compound have been determined. The vibrational frequencies of the fundamental modes of the compound have been precisely assigned, analyzed and the theoretical results were compared with the experimental data. The energies of important molecular orbitals of the compound are also evaluated from DFT method. The Frontier orbital energy gap (ELUMO–EHOMO) is found to be 6.2143 eV. The extreme limits of the electrostatic potential is +8.301e × 10–3 to –8.301e × 10–3 while the total electron density spreads between +3.835e × 10–2 to –3.835e × 10–2. 1H NMR and 13C NMR chemical shifts are measured and compared with their gauge independent atomic orbital (GIAO) calculated values. The n(O7) →π*(C13–O14) and π(C1–C6) →π*(C2–C3) transitions are best stablized with 48.40 and 21.03 kcal mol–1, respectively. In 3-trifluoromethylphenylchloroformate, the atoms C13 is favourable for electrophilic attack. The atoms C2 and C8 are more favourable for nucleophilic attack. The dual descriptors (Δfk, Δsk and Δωk) revealed that the order of nucleophilic attack is C1 > C4 > C2 > C8 > C5. Thus, the present investigation provides complete structure, vibrations and reactivity characteristics of the compound.

scholarly journals Theoretical Study of Solvent Effects on the Electronic and Thermodynamic Properties of Tetrathiafulvalene (TTF) Molecule Based on DFT

2021 ◽  
pp. 42-54
Author(s):  
Rabiu Nuhu Muhammad ◽  
N. M. Mahraz ◽  
A. S Gidado ◽  
A. Musa
Keyword(s):  
Thermodynamic Properties ◽  
Bond Length ◽  
Density Functional ◽  
Theoretical Study ◽  
Energy Gap ◽  
Basis Set ◽  
Basis Sets ◽  
Frontier Molecular Orbital ◽  
Orbital Energy ◽  
Chemical Hardness

Tetrathiafulvalene () is an organosulfur compound used in the production of molecular devices such as switches, sensors, nonlinear optical devices and rectifiers. In this work, a theoretical study on the effects of solvent on TTF molecule was investigated and reported based on Density Functional Theory (DFT) as implemented in Gaussian 03 package using B3LYP/6-31++G(d,p) basis set. Different solvents were introduced as a bridge to investigate their effects on the electronic structure. The HUMO, LUMO, energy gap, global chemical index, thermodynamic properties, NLO and DOS analysis of the TTF molecule in order to determine the reactivity and stability of the molecule were obtained. The results obtained showed that the solvents have effects on the electronic and non-linear-optical properties of the molecule. The optimized bond length revealed that the molecule has strong bond in gas phase with smallest bond length of about 1.0834Å than in the rest of the solvents. It was observed that the molecule is more stable in acetonitrile with HOMO-LUMO gap and chemical hardness of 3.6373eV and 1.8187eV respectively. This indicates that the energy gap and chemical hardness of TTF molecule increases with the increase in polarity and dielectric constant of the solvents. The computed results agreed with the results in the literature. The thermodynamics and NLO properties calculation also indicated that TTF molecule has highest value of specific heat capacity (Cv), total dipole moment () and first order hyperpolarizability () in acetonitrile, while acetone has the highest value of entropy and toluene has a slightly higher value of zero point vibrational energy (ZPVE) than the rest of the solvents. The results show that careful selection of the solvents and basis sets can tune the frontier molecular orbital energy gap of the molecule and can be used for molecular device applications.

Non Linear Optical, Thermodynamic Analysis and Spectroscopic Investigation of GPA Optical Materials

2017 ◽  
Vol 730 ◽  
pp. 106-111
Author(s):  
Xiao Jing Liu ◽  
Xin Sun ◽  
Jing Hua Guo
Keyword(s):  
Optical Materials ◽  
Density Functional ◽  
Nonlinear Optical ◽  
Energy Gap ◽  
Chemical Reactivity ◽  
Nbo Analysis ◽  
Basis Sets ◽  
Nucleophilic Attack ◽  
Charge Delocalization ◽  
Different Temperatures

In this work, density functional theory (DFT) calculations with B3LYP/6-311++G(d,p) basis sets was used to explore the electronic, structural, nonlinear optical and thermal properties aspects of glycine-phthalic acid (GPA) optical materials. Dipole moment, static polarizability and first hyperpolarizability analysis of the molecule have been performed. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. MEP study confirms GPA as an electron rich species and explains its electrophilic nature. MEP shows that this molecule has several possible sites for electrophilic/nucleophilic attack in which V(r) calculations provide insights into the order of preference. The low value of HOMO-LUMO energy gap reflects the high chemical reactivity, low chemical stability and hardness of GPA molecule. Thermodynamic properties of the title compound have been calculated at different temperatures and the results reveal that the standard heat capacities (Cp), standard entropies (S) and standard enthalpy (H) increase with rise in temperature. These results discussed in this study will upsurge the knowledge to design and synthesize new type nonlinear optical materials with exceptional chemical and physical properties.

A chromium carbene (OC)5Cr=C(OEt)(–C≡C–Ph): Quantum mechanical study of molecular structure, HOMO–LUMO analysis, IR spectroscopy, natural bond orbital analysis

2015 ◽  
Vol 14 (03) ◽  
pp. 1550022 ◽  
Author(s):  
Reza Ghiasi
Keyword(s):  
Electron Density ◽  
Chemical Shifts ◽  
Structural Characteristics ◽  
Structural Parameters ◽  
Atomic Orbital ◽  
Polarizable Continuum Model ◽  
Topological Parameters ◽  
H Nmr ◽  
Quantum Mechanical Study ◽  
Chromium Carbene

In this work, the structural, electronic properties, 13 C and 1 H NMR parameters and first hyperpolarizability of a chromium carbene ( OC )5 Cr = C ( OEt )(– C ≡ C – Ph ) complex were theoretically computed in gas phase and different solvents. Also, the solvent effect on structural parameters, frontier orbital energies, – C ≡ C – and C ≡ O stretching frequencies of complex has been carried out based on polarizable continuum model (PCM). The results indicate that the polarity of solvents has played a significant role on the structures and properties of complex. 1 H and 13 C NMR chemical shifts were calculated by using the gauge-independent atomic orbital (GIAO) method. In analyzing the structural characteristics of this structure, Cr – CO and Cr – C carbene bonds were identified and characterized in detail by topological parameters such as electron density ρ(r) and Laplacian of electron density ∇2ρ(r) from Bader's atom in molecules theory.

Acrylonitrile (AN)–Cu9(100) interfaces: Electron distribution and nature of bonded interactions

2003 ◽  
Vol 81 (6) ◽  
pp. 542-554 ◽  
Author(s):  
Petar M Mitrasinovic
Keyword(s):  
Electron Density ◽  
Molecular Orbital ◽  
Density Functional ◽  
Electron Distribution ◽  
Atomic Orbital ◽  
Interfacial Interactions ◽  
Total Electron Density ◽  
Total Electron ◽  
Topological Features ◽  
The One

There is a fundamental interest in the investigation of the interfacial interactions and charge migration processes between organic molecules and metallic surfaces from a theoretical standpoint. Quantum mechanical (QM) concepts of bonding are contrasted, and the vital importance of using combined QM methods to explore the nature of the interfacial interactions is established. At the one-electron level, the charge distribution and nature of bonded interactions at the AN–Cu9(100) (neutral and charged (–1)) interfaces are investigated by both the Becke (B) – Vosko (V) – Wilk (W) – Nusair (N)/DZVP density functional theory (DFT) method and the MP2/6–31+G* strategy within the conceptual framework provided by natural bond orbital (NBO) – natural atomic orbital (NAO) population analysis and Atoms-In-Molecules (AIM) theory. By this approach, the interfacial interactions are given physical definitions free of any assumptions and are visualized by using the topological features of the total electron density. A natural link between the electron density on the one side and the shapes (not energies) of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) on the other side is clarified. The question of whether the spatial extents of the HOMO and LUMO resemble the corresponding spatial maps of the negative (charge locally concentrated) and positive (charge locally depleted) Laplacian of the total electron density in [AN–Cu9(100)]–1 is addressed.Key words: AN–Cu9(100) interfaces, NBO–NAO population, electron distribution, AIM, bonded interactions.

A theoretical study of the 77Se NMR and vibrational spectroscopic properties of SenS8–n ring molecules

2002 ◽  
Vol 80 (11) ◽  
pp. 1435-1443 ◽  
Author(s):  
J Komulainen ◽  
R S Laitinen ◽  
R J Suontamo
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Chemical Shifts ◽  
Atomic Orbital ◽  
Geometry Optimization ◽  
Spectroscopic Properties ◽  
Basis Sets ◽  
Orbital Method ◽  
Hybrid Functional ◽  
Ring Molecules

The structures and spectroscopic properties of SenS8–n ring molecules have been studied by the use of ab initio molecular orbital techniques and density functional techniques involving Stuttgart relativistic large core effective core potential approximation with double zeta basis sets for valence orbitals augmented by two polarization functions for both sulfur and selenium. Full geometry optimizations have been carried out for all 30 isomers at the Hartree-Fock level of theory. The optimized geometries and the calculated fundamental vibrations and Raman intensities of the SenS8–n molecules agree closely with experimental information where available. The nuclear magnetic shielding tensor calculations have been carried out by the Gauge-independent atomic orbital method at the DFT level using Becke's three-parameter hybrid functional with Perdew/Wang 91 correlation. The isotropic shielding tensors correlate well with the observed chemical shift data. The calculated chemical shifts provide a definite assignment of the observed 77Se NMR spectroscopic data and can be used in the prediction of the chemical shifts of unknown SenS8–n ring molecules.Key words: selenium sulfides, ab initio, DFT, effective core potentials, geometry optimization, energetics, fundamental vibrations, 77Se chemical shifts.

SYNTHESIS AND GIAO NMR CALCULATIONS FOR TWO DIASTEREOISOMERS OF 2′-ACETYLOXY-2′-PHENYLSPIRO[INDENO[1,2-b]QUINOXALIN-11,1′-CYCLOPROPANE]

2012 ◽  
Vol 11 (06) ◽  
pp. 1227-1236 ◽  
Author(s):  
MASOUD SHAABANZADEH ◽  
HAMID HASHEMIMOGHADDAM ◽  
MARYAM BIKHOF TORBATI ◽  
TAHEREH SOLEYMANI AHOEE
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Atomic Orbital ◽  
Basis Sets ◽  
Computational Results ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Chemical Structures ◽  
B3lyp Method ◽  
Experimental Values

Two diastereoisomers of 2′-acetyloxy-2′-phenylspiro[indeno[1,2-b]quinoxalin-11,1′-cyclopropane] were synthesized and their 1 H NMR spectra were recorded. Their chemical structures were fully optimized at B3LYP/6-311+G(d,p) level of theory using the Gaussian 03W program package. The 1 H NMR chemical shifts were calculated for geometry-optimized structures of the diastereoisomers with the gauge independent atomic orbital (GIAO) and B3LYP method with the 6-311+G(d,p), 6-311++G(d), 6-31++G(d,p) and 6-31+G(d) basis sets. The computational results were then compared with the experimental values and the structures associated with each spectrum were assigned.

scholarly journals Estimation of the Efficiency of Corrosion Inhibition by Zn-Dithiocarbamate Complexes: a Theoretical Study

2021 ◽  
pp. 3323-3335
Author(s):  
Mustafa M. Kadhim ◽  
Layla A. Al. Juber ◽  
Ahmed S. M. Al-Janabi
Keyword(s):  
Electron Density ◽  
Density Functional ◽  
Room Temperature ◽  
Theoretical Study ◽  
Energy Gap ◽  
Basis Set ◽  
Total Electron Density ◽  
Functional Theory ◽  
Total Electron ◽  
Homo Lumo

    Seven Zn-dithiocarbamate complexes were suggested as corrosion inhibitors. Density functional theory (DFT) was used to predict the ability of inhibition. Room temperature conditions were applied to suggest the optimization of complexes, physical properties, and corrosion parameters. In addition, the HOMO, LUMO, dipole moment, energy gap, and other parameters were used to compare the inhibitors efficiency. Gaussian 09 software with LanL2DZ basis set was used. Total electron density (TED) and electrostatic surface potential (ESP) were utilized to show the sites of adsorption according to electron density.

Electronic Property and Reactivity of (Hydroperoxo) Metal Compounds

2001 ◽  
Vol 56 (1-2) ◽  
pp. 144-153 ◽  
Author(s):  
Yuzo Nishida ◽  
Satoshi Nishino
Keyword(s):  
Carbon Atom ◽  
Oxygen Atom ◽  
Electron Density ◽  
Metal Ion ◽  
Coupling Reaction ◽  
Metal Species ◽  
Nucleophilic Attack ◽  
Total Electron Density ◽  
Total Electron ◽  
Oxygen Atoms

Abstract DFT calculations were done for the (hydroperoxo)metal complexes with η1-coordination mode, where metal ions are Fe(III), Al(III), Cu(II) and Zn(II). Results shows that 1) the electron density at the two oxygen atoms of the hydroperoxide ion is highly dependent on the angle O-O-H in M-OOH species and the difference in electron density between the two oxygen atoms reaches a maximum at the angle O-O-H = 180°, 2) total electron density at the two oxygen atoms of the peroxide ion increases by approach of methane to the (hydro-peroxo)metal species in the cases of Fe(III) and Cu(II); on the other hand, significant decrease of the electron density on peroxide oxygen atoms was observed for the cases of Al(III) and Zn(II) compounds. These findings suggest that the (hydroperoxo)metal species acts as an electrophile in the former cases (M = Fe(III), Cu(II)) and as a nucleophile for the latter two compounds (M = Zn(II), Al(III)). The electrophilicity observed for the Fe(III) and Cu(II) complexes is attributed to the presence of unoccupied-or half-filled d-orbitals interacting with the hydroperoxide ion. 3) Two oxygen atoms of the (hydroperoxo)-com-pounds of Fe(III) and Cu(II) complexes exhibit quite different reactivity toward the substrate, such as methane. When methane approaches the oxygen atom which is coordinated to a metal ion, a strong decrease of electron density at the methane carbon atom occurs with concomitant increase of electron density at the peroxide oxygen atoms inducing its hetero-lytic O-O cleavage. When methane approaches the terminal oxygen atom, an oxidative coupling reaction occurs between peroxide ion and methane; at first a nucleophilic attack by the terminal electron-rich oxygen atom occurs at the carbon atom to induce C-O bond formation, and a subsequent oxidative electron transfer proceeds from substrate to the metal-peroxide species yielding CH3 -OOH, CH3OH, or other oxidized products. These results clearly de­monstrate that the (hydroperoxo)-metal compound itself is a rather stable compound, and activation of the peroxide ion is induced by interaction with the substrate, and the products obtained by the oxygenation reaction are dependent on the chemical property of the sub­ strate, redox property of a metal ion, and stability of the compounds formed in the intermediate process.

scholarly journals Analysis of polarization in QM/MM modelling of biologically relevant hydrogen bonds

2008 ◽  
Vol 5 (suppl_3) ◽  
pp. 207-216 ◽  
Author(s):  
Kittusamy Senthilkumar ◽  
Jon I Mujika ◽  
Kara E Ranaghan ◽  
Frederick R Manby ◽  
Adrian J Mulholland ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Density Functional ◽  
Bond Formation ◽  
Basis Sets ◽  
Total Electron Density ◽  
Functional Theory ◽  
Hydrogen Bond Formation ◽  
Total Electron ◽  
Biologically Relevant ◽  
Limited Basis

Combined quantum mechanics/molecular mechanics (QM/MM) methods are increasingly important for the study of chemical reactions and systems in condensed phases. Here, we have tested the accuracy of a density functional theory-based QM/MM implementation (B3LYP/6-311+G(d,p)/CHARMM27) on a set of biologically relevant interactions by comparison with full QM calculations. Intermolecular charge transfer due to hydrogen bond formation is studied to assess the severity of spurious polarization of QM atoms by MM point charges close to the QM/MM boundary. The changes in total electron density and natural bond orbital atomic charges due to hydrogen bond formation in selected complexes obtained at the QM/MM level are compared with full QM results. It is found that charge leakage from the QM atoms to MM atomic point charges close to the QM/MM boundary is not a serious problem, at least with limited basis sets. The results are encouraging in showing that important properties of key biomolecular interactions can be treated well at the QM/MM level employing good-quality levels of QM theory.

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