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2023, Journal of Kufa for Chemical Sciences
In this work, theoretical computations were performed using the Gaussian application. The results of theoretical calculations applying the density functional theory method (DFT) revealed that the azo group of -N=N-possesses a UV spectrum computed employing DFT-TD in the range of 250-500 nm. Several physical parameters were also calculated in this study, including Dipole moment (μ; Debye), HOMO and LUMO energies (EHOMO, ELUMO), energy gap (ΔEg in ev), ionization energy (IP in ev), electronic affinity, hardness, electronegativity, and the electrophiles (Ꞷ, Ꞷ, EA, ɳ, in ev), respectively.
European Journal of Chemistry, 2018
New heterocyclic azo compounds were prepared by coupling the diazonium salts with N-(4-methylphenyl)maleimide with various different sulfa compounds. The structure of heterocyclic azo compounds was determined by MS, FT-IR and 1H NMR techniques. The density function theory calculation at the B3LYP method with 6-311G(d,p) basis set is used to investigate the electronic structures of the prepared heterocyclic azo compounds. Mulliken charge distributions and HOMO-LUMO energies of the mentioned compounds have been also computed by same method and basis set.
Journal of Molecular Liquids, 2018
Three azo-derivatives: 2, 2′-Dihydroxyazobenzene (DHAB), Sudan Orange G (SOG) and 4-(Phenylazo) diphenylamine (PDA) were studied in this paper from quantum-mechanical and spectral point of view. The nature and the contribution of the intermolecular interactions to the spectral shifts in the solutions of the studied azo-derivatives were established based on the existent theories. Some electro-optical parameters of the studied molecules were calculated with Spartan 14 software using Density Functional Theory (DFT) employing the B3LYP model and the standard 6-31G* basis set. The polarizability and dipole moment in the excited states were estimated considering the variation of the angle between dipole moments in electronic states giving the visible absorption band.
Journal of Molecular Modeling, 2015
Density functional theory (DFT) calculations have been used to investigate the structural properties, dipole moments, polarizabilities, Gibbs energies, hardness, electronegativity, HOMO/LUMO energies, and chemical potentials of trans and cis configurations of eight parasubstituted azobenzene derivatives. All properties have been obtained using the B3LYP functional and 6-31++G(d,p) basis set. The planar structures have been obtained for all optimized trans configurations. The energy difference between trans and cis configurations for considered derivatives was found to be between 64.2-73.1 kJ/mole. It has been obtained that the p-aminodiazo-benzene (ADAB) has the difference in the dipole moments between trans and cis forms higher than for trans and cis azobenzene.
ACS Omega, 2020
In the present work, a theoretical study was carried out to study the molecular structure, harmonic vibrational frequencies, normal force field calculations, and Raman scattering activities for fluorene π-conjugation spacer containing azo-based dye named trans-and cis-bis(9H-fluoren-2-yl)diazene (AzoFL) at density functional theory using B3LYP (Becke-3−Lee−Yang−Parr) functional and 6-31+G(d,p) basis set. The theoretical calculations have also been performed with fluorene and the trans-and cis-isomers of diazene, difluorodiazene by the same method DFT-B3LYP/6-31+G(d,p) and basis set. The present DFT calculation shows that the trans-AzoFL is more stable than the cis-AzoFL by 16.33 kcal/mol. We also report the results of new assignments of vibrational frequencies obtained on the basis of the present calculations. Timedependent DFT (TD-DFT) and ZIndo calculations have been performed to study the UV−vis absorption behavior and frontier molecular orbitals for the above-mentioned compounds. The UV− vis spectrum from TD-DFT calculation shows the π−π* transition bands at λ max 423.53 nm (ε max 6.0 × 10 4 M −1 cm −1) and at λ max 359.45 nm (ε max 1.7 × 10 4 M −1 cm −1), respectively, for trans-and cis-AzoFL. Compared to parent trans-diazene (λ max 178.97 nm), a significant variation to longer wavelength (∼245 nm) is observed due to the incorporation of the fluorene (FL) ring into the −N N− backbone. The co-planarity of the two FL rings with the longer NN bond length compared to the unsubstituted parent diazene indicates the effective red shift due to the extended π-conjugation in trans-AzoFL. The nonplanarity of cis-AzoFL (48.1°t ilted about the C−N bond relative to the planar NN−C bond) reflects its ∼64 nm blue shift compared to that of transcounterpart.
How to cite this paper: Nkungli, N.K., Ghogomu, J.N., Nogheu, L.N. and Gadre, S.R. (2015) DFT and TD-DFT Study of Bis[2-(5-Amino-[1,3,4]-Oxadiazol-2-yl) Phenol](Diaqua)M(II) Complexes [M = Cu, Ni and Zn]: Electronic Structures, Properties and Analyses. Computational Chemistry, 3, 29-44. http://dx. Abstract Ground state geometries, spectral (IR and UV-Vis) properties, analysis of frontier molecular orbit-als (FMOs), natural bond orbital (NBO) analysis and molecular electrostatic potential (MEP) surfaces of three transition metal complexes [Cu(AOYP)2(OH2)2] (A), [Ni(AOYP)2(OH2)2] (B) and [Zn-(AOYP)2(OH2)2] (C), have been studied theoretically by the Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) methods. AOYP is the oxadiazole ligand 2-(5-amino-[1,3,4]-oxadiazol-2-yl)phenol. The geometries of these complexes were initially optimized using two basis sets: LAN2DZ and a generic basis set, the latter of which was selected for subsequent analysis. The stability of the complexes arising from intramolecular interactions and electron delocalization was estimated by natural bond orbital (NBO) analysis. The NBO results showed significant charge transfer from lone pair orbitals on the AOYP donor atoms O19, O21, N15 and N36 to central metal ions in the complexes, as well as to the benzene and oxadiazole rings. The electronic spectrum of (A) showed bands at 752 and 550 nm mainly attributable to ligand-to-metal charge transfer (LMCT) transitions, and a band at 446 nm assigned to a d-d transition. The electronic spectrum of (B) consisted of bands at 540, 463 and 395 nm mainly due to d-d transitions. Calculated electronic bands for (C) occurred at 243, 238 and 235 nm, arising from intra-ligand charge transfer (ILCT) transitions within AOYP. A good agreement in terms of band positions was found between experimental and calculated absorption spectra of the complexes.
The Journal of Physical Chemistry A, 2000
2019
3 - p -Chlorobenzyl -4-[3-(3-methoxybenzoxy)-benzylidenamino]-4,5-dihydro-1 H -1,2,4-triazol-5-one were optimized using DFT(B3LYP)/HF methods and 6-311G(d) and 3-21G levels. The 13 C-NMR and 1 H-NMR (in gas phase/DMSO solvent with GIAO method), FT-IR and UV-vis spectral values were performed using Gaussian09W program package. Theoretical spectral values of the molecule were calculated and compared with experimental data. The FT-IR spectrums were drawn the same methods and levels. Furthermore, the molecular potential surfaces such as the molecular electrostatic potential (MEP), electron density, electron spin potential (ESP), total density and contour maps of titled molecule have been drawn. The electron affinity (A), electronegativity (χ), global hardness (η)/softness (σ), ionization potential (I), E LUMO -E HOMO energies, energy gap (ΔE), thermal capacity (CV), mulliken atomic charges, entropy (S), total energy, thermal energies (E), bond angles, dipole moments and bond lengths of ...
1995
ABSTRACT Density functional (DF) calculations are reported for the ground-state geometries and harmonic vibrational frequencies of ZnX,(X= C1, Br, I). Both local density approximation (LDA) and non-local generalized gradient approximation (GGA) functionals were investigated using an STO basis set of triple-< quality for the metal and double-< plus polarization function quality for the halogen.
Chemical Physics Letters - CHEM PHYS LETT, 2007
Theoretical calculations for the electron binding energies (EBEs) of several organic azides including hydrazoic acid, methyl azide, ethyl azide, 2-chloroethyl azide, 2-azidoethanol, azidoacetone, 2-azidoacetic acid, 3-azido-2-butanone, and 2-azidoethyl acetate are reported. EBEs were calculated with ab initio Green's function (GF) and density functional theory (DFT). Complete basis-set extrapolated coupled cluster calculations with single, double, and perturbative triple excitations [CCSD(T)] for the first ionization energy of azides are also reported. It is shown that EBEs from GF and DFT calculations are in better agreement with experiment than Hartree-Fock predictions.
Chemistry - A European Journal, 2004
REPRINT Alike yet different: Two bis(azo) derivatives that can be viewed as a pair of azobenzene units sharing one of their phenyl rings and positioned either in meta or para positions relative to each other, exhibit markedly different photoisomerisation properties. Preferentially localised (meta) or delocalised (para) electronic structures (see for instance the LUMO orbitals shown in the illustration) are responsible for the observed behaviour. These results are relevant for the design of novel photoelastic oligomers and polymers.
International Journal of Computational and Theoretical Chemistry
Computational investigation on the ground state properties of trans-azobenzene and four kinds of hydroxy-ended azobenzene-type chromophores containing different substituent groups as electron donor and acceptor in different solvent media was carried out. The effects ofsubstituents-I 2 ,-OHand-CH 3 ,-NH 2 , and-Cl 2 on the electronic properties like the E HOMO , E LUMO , band gap, dipole moments, global hardness, electrophilicity indices were studied using the Ab initio restricted DFT self-consistent field method with the Becke Three Lee Yang Parr (B3LYP)/6-31G* method in vacuum, water, diethylether, ethanol and acetone. The results showed that these properties were altered upon substitution with different groups. The azobenzene gave a slight difference in its band gap in different solvent changing from (3.95 eV) in vacuum to the lowest (3.87 eV) in acetone but changes drastically as we introduce different substituents. It was also found that the dipole moment (µ), polarizability (α), absorption wavelength (λ ab) gave slight change in different solvents but rapidly increased as the band gap reduces, invoking their reactivities. They are also red-shifted as different substituents are added. Of all the studied molecules, compound H gave the lowest band gap of 0.46 eV, the highest dipole moment (875.02 D), the highest polarizability (64.97C.m 2 V-1) and it is the most red-shifted (401.13 nm). Molecule H therefore, has the lowest band gap, highest polarizability and dipole moment. It also has the highest molecular size and the highest planarity. This means that the molecule is the most reactive, most polarizable, highest electro-optic response and it is the softest.
International Journal of Physical Sciences, 2013
In this work, the structural and electronic properties of 4-[(E)-[4-(trifloromethyl)-1,3-benzothiazol-2yl]azo]naphthalen-1-ol (ortho-OH) and 1-[(E)-[4-(trifloromethyl)-1,3-benzothiazol-2-yl]azo]naphthalen-2-ol (para-OH) using density functional theory (DFT) were presented. The calculated vibrational frequencies were compared very well with experimental. The total energy for the isomers A and B were-4277242.55 and-4277216.21 kJ/mol respectively; thus structural relaxation was observed in isomer A which resulted into extra thermodynamic stability over isomer B by 26.34 kJ/mol. 13 C and 1 H NMR chemical shifts for two isomers were calculated and compared. Electrophilicity index revealed that isomer A would be mote reactive towards nucleophiles more than isomer B.
The crystal structure of (C 6 H 20 N 3 )SbCl 5 ·Cl·H 2 O is built up of [NH 3 (CH 2 ) 3 NH 2 (CH 2 ) 3 NH 3 ] 3+ cations, [SbCl 5 ] 2− anions, free Cl − anions and neutral water molecules connected together by N\ \H⋯Cl, N\ \H⋯O and O\ \H⋯Cl hydrogen bonds. The optical band gap determined by diffuse reflection spectroscopy (DRS) is 3.78 eV for a direct allowed transition. Optimized molecular geometry, atomic Mulliken charges, harmonic vibrational frequencies, HOMO-LUMO and related molecular properties of the (C 6 H 20 N 3 )SbCl 5 ·Cl·H 2 O compound were calculated by Density functional theory (DFT) using B3LYP method with GenECP sets. The calculated structural parameters (bond lengths and angles) are in good agreement with the experimental XRD data. The vibrational unscaled wavenumbers were calculated and scaled by a proper scaling factor of 0.984. Acceptable consistency was observed between calculated and experimental results. The assignments of wavenumbers were made on the basis of potential energy distribution (PED) using Vibrational Energy Distribution Analysis (VEDA) software. The HOMO-LUMO study was extended to calculate various molecular parameters like ionization potential, electron affinity, global hardness, electro-chemical potential, electronegativity and global electrophilicity of the given molecule.
Journal of Spectroscopy
The study under consideration represents the computational calculations of Azo-based direct dye named p-(dimethylamino)azobenzene (DMAB) under the effect of solvents with different relative permittivities. A density functional theory (DFT) method at the B3LYP level with 6-311G++ was applied for the spectroscopic and structural analysis of the title compound. Calculations of geometric parameters (bond orders, bond lengths, and dihedral angles), electron densities, thermodynamic parameters, and orbital energies were performed for the title compound. Mulliken population analysis (MPA) as well as natural population analysis (NPA) was also performed at the B3LYP level with different solvents for finding solvent effects. In order to predict the reactivity of DMAB, molecular electrostatic potential (MESP) calculations were carried out for it. For vibrational analysis, the infrared (IR) spectra were computed for the title compound at the B3LYP/6-311G++ level in the gas phase and in differen...
Computational and Theoretical Chemistry, 2016
We present a theoretical study of the structure and electronic and optical properties of several L 2-M compounds where L is bis(N-(5-(4-methoxyphenyl)-1,3,4-oxadiazol-2-yl)ethanimidamidato, or C 11 H 11 N 4 O 2 , and M = Co, Ni, Cu, Zn, Pd, Cd. Our calculations are carried out in the framework of the density-functional theory (DFT) using several families of density functionals, namely semi-local functionals, global hybrids and range-separated hybrids. Our results reproduce well the experimental data concerning the structure of the recently synthetized L 2-Cu compound. We also present the infrared spectra and absorption spectra in the visible-UV domain. The changes induced by the substitution of the Cu atom by another metal atom are investigated.
Journal of Molecular Structure: THEOCHEM, 2003
In the present work, we report structural and electronic properties of a benzoin monomer named as 2-oxo-1,2-diphenylethyl-2-bromopropanoate (C 17 H 14 BrO 3). The previously synthesized compound is characterized by single crystal X-ray diffraction. The optimized molecular geometry (bond lengths, and bond angles), HOMO-LUMO analysis and molecular electrostatic potential (MEP) are calculated by density functional theory (DFT) and Hartree-Fock (HF) methods with 6-311G(d) basis set in the neutral ground state and using DFT methods for singly oxidized doublet, singly reduced doublet, and neutral triplet state for the benzoin compound. The X-ray structure determination of the compound is compatible with the geometric parameters calculated at B3LYP/6-311G(d). In the triplet state the HOMO-LUMO energy gap of 2.39 eV which indicates semiconductor property is recommended for the photovoltaic devices.
Journal of the American Chemical Society, 2012
We present a comprehensive electronic structure analysis of structurally simple BN heterocycles using a combined UV-photoelectron spectroscopy (UV-PES) / computational chemistry approach. Gas-phase He I photoelectron spectra of 1,2-dihydro-1,2-azaborine 1, N-Me-1,2-BN-toluene 2, and N-Me-1,3-BN-toluene 3 have been recorded, assessed by density functional theory calculations, and compared with their corresponding carbonaceous analogues benzene and toluene. The first ionization energies of these BN heterocycles are in the order N-Me-1,3-BNtoluene 3 (8.0 eV) < N-Me-1,2-BN-toluene 2 (8.45 eV) < 1,2-dihydro-1,2-azaborine 1 (8.6 eV) < toluene (8.83 eV) < benzene (9.25 eV). The computationally determined molecular dipole moments are in the order 3 (4.577 Debye) > 2 (2.209 Debye) > 1 (2.154 Debye) > toluene (0.349 Debye) > benzene (0 Debye) and are consistent with experimental observations. The λ max in the UV-Vis absorption spectra are in the order 3 (297 nm) > 2 (278 nm) > 1 (269 nm) > toluene (262 nm) > benzene (255 nm). We also establish that the measured anodic peak potentials and electrophilic aromatic substitution (EAS) reactivity of BN heterocycles 1-3 are consistent with the electronic structure description determined by the combined UV-PES/computational chemistry approach.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2010
The structure and spectroscopic properties of 5-methyl-2-(8-quinolinyl)benzoxazole and its complexes with Zn(II) ion were studied using a DFT and TD DFT methods with def2-TZVP basis set. It was shown that the type of functional used (B3-LYP or pbe0) implemented in TURBOMOLE package does not have essential influence on the geometry (small differences in bond length, valence and dihedral angles) of studied compounds in both ground and excited states. However, significant differences were obtained for the position of vertical absorption and emission transition but not for the oscillator strength of transition. Application of pbe0 functional seems to reproduce better the experimental spectrum.
Journal of Molecular Modeling, 2007
We report the structural properties, infrared (IR) and Raman spectra, dipole moment, polarizability, hardness and chemical potential of the trans and cis configurations of 4hydroxyazobenzene calculated using the B3LYP functionals. All calculations were performed with the following basis sets: 6-31G, 6-31++G, 6-31G(d,p), 6-31++G(d,p), 6-31G(2d,2p), 6-31++G(2d,2p) and 6-311++G(2d,2p). We observed that 6-31++G(d,p) gives similar results as 6-311++G(2d,2p).Consequently SVWN and PW91 methods were also used in association with 6-31++G(d,p) to test the influence of the different models of exchange and correlation functionals. A planar structure was obtained for all the optimized trans configuration structures. In both isomers, the presence of the hydroxyl group leads to an asymmetry in certain of the structural parameters. From these results two IR or Raman active frequencies can be easily used to distinguish trans and cis configurations. The trans configuration is found to be more stable than cis configuration by 672 kJ/mol at 0K. The difference of the dipole moment between trans and cis for 4-hydroxyazobenzene was found to be lower than for trans and cis azobenzene.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2013
A systematic vibrational spectroscopic assignment and analysis of carbamazepine has been carried out by using FT-IR, FT-Raman and UV spectral data. The vibrational analysis were aided by electronic structure calculations-ab initio (RHF) and hybrid Density Functional methods (B3LYP) performed with standard basis set 6-31G(d,p). Molecular equilibrium geometries, electronic energies, natural bond order analysis, harmonic vibrational frequencies and IR intensities have been computed. A detailed interpretation of the vibrational spectra of the molecule has been made on the basis of the calculated Potential Energy Distribution (PED) by VEDA program. UV-visible spectrum of the compound was also recorded and the electronic properties, such as HOMO and LUMO energies and λ max were determined by HF/6-311++G(d,p) Time-Dependent method. The thermodynamic functions of the title molecule were also performed using the RHF and DFT methods. The restricted Hartree-Fock and density functional theory-based nuclear magnetic resonance (NMR) calculation 2 procedure was also performed, and it was used for assigning the 13 C and 1 H NMR chemical shifts of carbamazepine.
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