Dependence on the geometry and on the basis set of localized orbital energy and moment contributions

: Gallic acid is abundantly found in amla (Phyllanthus emblica), a deciduous of the family phyllanthaceae. Gallic acid, the major constituent of the plant was methylated to 3,4,5 trimethoxy gallic acid, which then underwent steglich esterification first with paracetamol and then with 4-hydroxy acetophenone to yield 4-acetamidophenyl 3,4,5-trimethoxybenzoate and 4-acetyl phenyl 3,4,5-trimethoxybenzoate “respectively”. 1H NMR, 13C NMR, UV, FT-IR and mass spectroscopy were used to characterize the synthesized compounds. Density functional theory (B3YLP) using 6-31G (d,p) basis set have been used for quantum chemical calculations. AIM (Atom in molecule) approach depicted weak molecular interactions within the molecules whereas the reactive site and reactivity within the molecule were examined by global and local reactivity descriptors. The HOMO and LUMO energies and frontier orbital energy gap were calculated by time dependant DFT approach using IEFPCM model. Small value for HOMO–LUMO energy gap indicated that easier charge transfer occurs within compound 4. The nucleophilic and electrophilic reactivity were determined by MEP (molecular electrostatic potential) experiment. Polarizability, dipole moment, and first hyperpolarizability values were calculated to depict the NLO (nonlinear optical) property of both the synthesized compounds. The antimicrobial activity was also carried out and broad spectrum antibacterial activity against several strains of bacteria and certain unicellular fungi were exhibited by synthesized compound 3.

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Localized orbital corrections applied to thermochemical errors in density functional theory: The role of basis set and application to molecular reactions

The Journal of Chemical Physics ◽

10.1063/1.3008062 ◽

2008 ◽

Vol 129 (21) ◽

pp. 214105 ◽

Cited By ~ 17

Author(s):

Dahlia A. Goldfeld ◽

Arteum D. Bochevarov ◽

Richard A. Friesner

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Basis Set ◽

Functional Theory ◽

Localized Orbital ◽

Molecular Reactions

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

Asian Journal of Research and Reviews in Physics ◽

10.9734/ajr2p/2021/v5i230162 ◽

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.

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Theoretical study of first row transitional metals effects on stabilization of verdoheme analogues

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424619501311 ◽

2019 ◽

Vol 23 (10) ◽

pp. 1100-1109

Author(s):

Afsaneh Taghizadeh ◽

Maryam Daghighi Asli ◽

Parisa Rajabali Jamaat

Keyword(s):

Chemical Potential ◽

Dft Method ◽

Basis Set ◽

Orbital Energy ◽

Central Metal ◽

Transitional Metals ◽

Solvent Phase ◽

Energy Formula ◽

Homo And Lumo

Heme catabolism is an important physiological process that converts heme to biliverdin in the presence of heme oxygenase which has an essential role in destroying unwanted heme. Verdohemes, the green iron (II) complexes of the 5-oxaporphyrin macrocycle are produced by oxidative destruction of heme. The main goal of this study is clarification of the central metal effect on stabilization of metal 5-oxaporphyrin molecules. To investigate the role of central metal on geometric and electronic properties of five coordinated verdoheme analogues, the first row transitional metals, including Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn, as the central metal of five-coordinated metal 5-oxaporphyrins were systematically calculated without any symmetry constraint by using the B3LYP as DFT method and the 6-31G basis set in gas and solvent phases. According to the results, the stabilization energy of metal 5-oxaporphyrins increases with atomic mass in the solvent phase more than in the gas phase. By reviewing the properties such as the computed frontier orbital energy, HOMO and LUMO gap energy [Formula: see text], hardness [Formula: see text], chemical potential [Formula: see text], softness (s) and electrophilicity [Formula: see text], the pharmaceutical use of this compound can be discussed.

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Comparing Study of The Stability and spectral properties vibrations for some Tellurium (IV) compounds containing cycloctadienyl group by Quantum Mechanical Calculations

Baghdad Science Journal ◽

10.21123/bsj.10.3.1041-1049 ◽

2013 ◽

Vol 10 (3) ◽

pp. 1041-1049

Author(s):

Baghdad Science Journal

Keyword(s):

Density Functional ◽

Heat Of Formation ◽

Basis Set ◽

Orbital Energy ◽

Empirical Methods ◽

Geometrical Structures ◽

Functional Theory ◽

Exchange Correlation ◽

The Stability ◽

Semi Empirical

Density Functional Theory (DFT) with B3LYP hybrid exchange-correlation functional and 3-21G basis set and semi-empirical methods (PM3) were used to calculate the energies (total energy, binding energy (Eb), molecular orbital energy (EHOMO-ELUMO), heat of formation (?Hf)) and vibrational spectra for some Tellurium (IV) compounds containing cycloctadienyl group which can use as ligands with some transition metals or essential metals of periodic table at optimized geometrical structures.

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Molecular Orbital Calculations of Cu-Halides

Zeitschrift für Naturforschung A ◽

10.1515/zna-1981-1013 ◽

1981 ◽

Vol 36 (10) ◽

pp. 1095-1099 ◽

Cited By ~ 1

Author(s):

H. Itoh

Keyword(s):

Ab Initio ◽

Molecular Orbital ◽

Energy Levels ◽

Basis Set ◽

Orbital Energy ◽

Ionic Character ◽

Molecular Orbital Calculations ◽

Ab Initio Hf ◽

Mo Theory

An ab initio HF MO theory is applied to CuX, CuX2 (X = F and Cl) and (CuCl)3 . Although the detailed sequence of energy levels depends upon the basis set used, high-lying orbital energy levels have largely halogen p-like character, whereas low-lying orbital energy levels have largely Cu 3 d-like character. This is in agreement with the chemical intuition of a highly ionic character of these compounds.

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