scholarly journals EXTRACTION OF STRONTIUM(II) BY CROWN ETHER: INSIGHTS FROM DENSITY FUNCTIONAL CALCULATION

2012 ◽  
Vol 12 (3) ◽  
pp. 207-216 ◽  
Author(s):  
Saprizal Hadisaputra ◽  
Harno Dwi Pranowo ◽  
Ria Armunanto
Keyword(s):  
Crown Ether ◽  
Organic Solvent ◽  
Interaction Energy ◽  
Thermodynamic Parameters ◽  
Metal Ion ◽  
Density Functional ◽  
Pure Water ◽  
Density Functional Method ◽  
Basis Set ◽  
Solvent Phase

The structures, energetic and thermodynamic parameters of crown ethers with different cavity size, electron donating/withdrawing substituent groups and donor atoms have been determined with density functional method at B3LYP level of theory in gas and solvent phase. Small core quasi-relativistic effective core potentials was used together with the accompanying SDD basis set for Sr2+ and DZP basis set was used for crown ether atoms. Natural bond orbital (NBO) analysis was evaluated to characterize the distribution of electrons on the complexes. The interaction energy is well correlated with the values of Strontium charge after complexation, the second order interaction energies (E2) and HOMO-LUMO energy gab (∆Egab). The interaction energy and thermodynamics parameters in gas phase are reduced in solvent phase as the solvent molecules weaken the metal-crown ether interaction. The thermodynamic parameters indicated that less feasibility to extract Sr2+ ion directly from pure water without presence of organic solvent. The theoretical values of extraction energy for Sr(NO3)2 salt from aqueous solution in different organic solvent is validated by the experimental trend. This study would have strong contribution in planning the experiments to the design of specific host ligand and screening of solvent for extraction of metal ion.

scholarly journals Origin Invariant Full Optical Rotation Tensor in the Length Dipole Gauge without London Atomic Orbitals

2021 ◽  
Author(s):  
Marco Caricato
Keyword(s):  
Electron Correlation ◽  
Density Functional ◽  
Optical Rotation ◽  
Density Functional Method ◽  
Functional Method ◽  
Basis Set ◽  
Rotation Tensor ◽  
Atomic Orbitals ◽  
Complete Basis Set ◽  
Approximate Wave

<div> <div> <div> <p>We present an origin-invariant approach to compute the full optical rotation tensor (Buckingham/Dunn tensor) in the length dipole gauge without recourse to London atomic orbitals, called LG(OI). The LG(OI) approach is simpler and less computationally demanding than the more common LG-London and modified velocity gauge (MVG) approaches and it can be used with any approximate wave function or density functional method. We report an implementation at coupled cluster with single and double excitations level (CCSD), for which we present the first simulations of the origin-invariant Buckingham/Dunn tensor in the length gauge. With this method, we attempt to decouple the effects of electron correlation and basis set incompleteness on the choice of gauge for optical rotation calculations on simple test systems. The simulations show a smooth convergence of the LG(OI) and MVG results with the basis set size towards the complete basis set limit. However, these preliminary results indicate that CCSD may not be close to a complete description of the electron correlation effects on this property even for small molecules, and that basis set incompleteness may be a less important cause of discrepancy between choices of gauge than electron correlation incompleteness. </p> </div> </div> </div>

A DENSITY FUNCTIONAL THEORY INVESTIGATION ON THE TAUTOMERS AND CRYSTAL OF 2-DIAZO-4,6-DINITROPHENOL

2004 ◽  
Vol 03 (04) ◽  
pp. 599-607 ◽  
Author(s):  
XUE-HAI JU ◽  
HE-MING XIAO
Keyword(s):  
Density Functional ◽  
Density Functional Method ◽  
Lattice Energy ◽  
Functional Method ◽  
Basis Set ◽  
Functional Theory ◽  
Basis Set Superposition Error ◽  
Conduction Bands ◽  
Valence Bands ◽  
Good Agreement

Density functional method was applied to the study of the highly efficient primary explosive 2-diazo-4,6-dinitrophenol (DDNP) in both gaseous tautomers and its bulk state. Two stable tautomers were located. It was found that the structure (I) with open diazo, i.e. with linear CNN, is more stable than that with diazo ring tautomer (II) of DDNP. The structure I is in good agreement with the structure in the bulk. The lattice energy is -89.01 kJ/mol, and this value drops to -83.29 kJ/mol when a 50% correction of the basis set superposition error was adopted. The frontier bands are quite flat. The carbon atoms in DDNP make up the upper valence bands. While the lower conduction bands mainly consist of carbon and diazo N atoms. The bond populations of C–N bonds (both C–Nitro and C–Diazo) are much less than those of the other bonds and the detonation may be initiated through the breakdown of C–N bonds.

scholarly journals Density functional theory study on the molecular structure of loganin

2011 ◽  
Vol 25 (6) ◽  
pp. 287-302 ◽  
Author(s):  
Anoop Kumar Pandey ◽  
Shamoon Ahmad Siddiqui ◽  
Apoorva Dwivedi ◽  
Kanwal Raj ◽  
Neeraj Misra
Keyword(s):  
Molecular Structure ◽  
Density Functional ◽  
Solid Phase ◽  
Density Functional Method ◽  
Functional Method ◽  
Basis Set ◽  
Equilibrium Geometry ◽  
B3lyp Method ◽  
Ft Ir ◽  
Detailed Interpretation

The computational Quantum Chemistry (QC) has been used for different types of problems, for example: structural biology, surface phenomena and liquid phase. In this paper we have employed the density functional method for the study of molecular structure of loganin. The equilibrium geometry, harmonic vibrational frequencies and infrared intensities were calculated by B3LYP/6-311G (d, p) method and basis set combinations. It was found that the optimized parameters obtained by the DFT/B3LYP method are very near to the experimental ones. A detailed conformational analysis was carried out. A detailed interpretation of the infrared spectra of loganin is also reported in the present work. The FT-IR spectra of loganin were recorded in solid phase. The thermodynamic calculations related to the title compound were also performed at B3LYP/6-311G (d, p) level of theory.

Theoretical Study of CN Radicals Chemisorption on the Electronic Properties of BC2N Nanotube

2017 ◽  
Vol 48 ◽  
pp. 38-48 ◽  
Author(s):  
Batoul Makiabadi ◽  
Mohammad Zakarianezhad ◽  
Shahin Mohammadzamani
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Density Functional Method ◽  
Nbo Analysis ◽  
Band Gap Energy ◽  
Functional Method ◽  
Basis Set ◽  
Hybrid Density Functional ◽  
Cn Radicals ◽  
Covalent Nature

In this work, we have investigated the adsorption behavior of the CN radicals on electronic properties of BC2N nanotube (BC2NNT) by means of the B3LYP hybrid density functional method using 6-31G(d) basis set. The results show that CN radicals can be chemically adsorbed on the nanotube. Based on the energy analysis, the most stable position of CN radical on the nanotube is C1 site. Also, the C-side complexes are more stable than the N-side complexes. We investigated the effects of CN radicals adsorption on the electronic properties of the BC2N nanotube. According to our calculations, band gap energy of the BC2NNT decreases with increasing the number of CN radicals. It is predicted that the conductivity and reactivity of nanotube increase by increasing the number of CN radicals. Based on the NBO analysis, in all complexes charge transfer occurs from nanotube to CN radical. The AIM results show that, the Xtube…YCN interaction has covalent nature. Generally, The BC2N nanotube can be used to as sensor for nanodevice applications.

AN AB INITIO STUDY OF INTERMOLECULAR INTERACTION OF HYDROGEN FLUORIDE TETRAMER

2006 ◽  
Vol 05 (02) ◽  
pp. 187-196 ◽  
Author(s):  
JINSHAN LI
Keyword(s):  
Interaction Energy ◽  
Intermolecular Interaction ◽  
Density Functional ◽  
Ring Structure ◽  
Membered Ring ◽  
Basis Set ◽  
Intermolecular Interaction Energy ◽  
B3lyp Method ◽  
Three Body ◽  
Intermolecular Distances

Possible HF tetramer geometries have been optimized employing the density functional B3LYP method and the aug-cc-pVQZ basis set. Deformation energy has been calculated at the B3LYP/aug-cc-pVQZ level. After the BSSE correction with the CP method, two-body intermolecular interaction energy, three-body nonadditive intermolecular interaction energy, and four-body nonadditive intermolecular interaction energy (Δ E c[4]) have been obtained at the levels of B3LYP/aug-cc–pVQZ, B3LYP/aug-cc-pVTZ//B3LYP/aug-cc-pVQZ, and MP2/aug-cc-pVTZ//B3LYP/aug-cc-pVQZ. Calculated results show that the three-body nonadditive intermolecular interaction energy is important for the optimized structures of HF tetramer. At the MP2/aug-cc-pVTZ//B3LYP/aug-cc-pVQZ level, the four-body nonadditive intermolecular interaction strength arrives at -4.5kJ/mol in the optimized eight-membered ring structure, but is extremely weak in other optimized structures. The comparison between MP2 and B3LYP calculated intermolecular interaction energies shows that the B3LYP method is applicable to the calculation of the intermolecular interaction energy of HF tetramer when the basis set reaches aug-cc-pVTZ. ΔEc[4] occupies 8–32% of the total intermolecular interaction energy when the intermolecular distances of the eight-membered ring structure are in the range of 1.06–1.37 Å.

scholarly journals Theoretical Study on the Extraction of Alkaline Earth Salts by 18-Crown-6: Roles of Counterions, Solvent Types and Extraction Temperatures

2014 ◽  
Vol 14 (2) ◽  
pp. 199-208 ◽  
Author(s):  
Saprizal Hadisaputra ◽  
Lorenz R Canaval ◽  
Harno Dwi Pranowo ◽  
Ria Armunanto
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Alkaline Earth ◽  
Theoretical Study ◽  
Polar Solvent ◽  
Density Functional Method ◽  
Nitrate Anion ◽  
Interaction Energies ◽  
Free Energies ◽  
Solvent Phase

The roles of counterions, solvent types and extraction temperatures on the selectivity of 18-crown-6 (L) toward alkaline earth salts MX2 (M = Ca, Sr, Ba; X = Cl-, NO3-) have been studied by density functional method at B3LYP level of theory in gas and solvent phase. In gas phase, the chloride anion Cl- is the preference counterion than nitrate anion NO3-. This result is confirmed by the interaction energies, the second order interaction energies, charge transfers, energy difference between HOMO-LUMO and electrostatic potential maps. The presence of solvent reversed the gas phase trend. It is found that NO3- is the preference counterion in solvent phase. The calculated free energies demonstrate that the solvent types strongly change the strength of the complex formation. The free energies are exothermic in polar solvent while for the non polar solvent the free energies are endothermic. As the temperature changes the free energies also vary where the higher the temperatures the lower the free energy values. The calculated free energies are correlated well with the experimental stability constants. This theoretical study would have a strong contribution in planning the experimental conditions in terms of the preference counterions, solvent types and optimum extraction temperatures.

scholarly journals Halogen Interactions in Halogenated Oxindoles: Crystallographic and Computational Investigations of Intermolecular Interactions

Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5487
Author(s):  
Rodrigo A. Lemos Silva ◽  
Demetrio A. da Silva Filho ◽  
Megan E. Moberg ◽  
Ted M. Pappenfus ◽  
Daron E. Janzen
Keyword(s):  
Interaction Energy ◽  
Intermolecular Interactions ◽  
Density Functional ◽  
Basis Set ◽  
Interaction Energies ◽  
Functional Theory ◽  
Basis Set Superposition Error ◽  
Reduced Density Gradient ◽  
Moller Plesset ◽  
Reduced Density

X-ray structural determinations and computational studies were used to investigate halogen interactions in two halogenated oxindoles. Comparative analyses of the interaction energy and the interaction properties were carried out for Br···Br, C-H···Br, C-H···O and N-H···O interactions. Employing Møller–Plesset second-order perturbation theory (MP2) and density functional theory (DFT), the basis set superposition error (BSSE) corrected interaction energy (Eint(BSSE)) was determined using a supramolecular approach. The Eint(BSSE) results were compared with interaction energies obtained by Quantum Theory of Atoms in Molecules (QTAIM)-based methods. Reduced Density Gradient (RDG), QTAIM and Natural bond orbital (NBO) calculations provided insight into possible pathways for the intermolecular interactions examined. Comparative analysis employing the electron density at the bond critical points (BCP) and molecular electrostatic potential (MEP) showed that the interaction energies and the relative orientations of the monomers in the dimers may in part be understood in light of charge redistribution in these two compounds.

scholarly journals Study Of Energy And Structure On Intermolecular Interactions In Organic Solvents Using Computational Chemistry Method

2021 ◽  
Vol 4 (2) ◽  
pp. 79
Author(s):  
Nur Aisah Malau ◽  
Asep Wahyu Nugraha
Keyword(s):  
Organic Solvent ◽  
Computational Chemistry ◽  
Interaction Energy ◽  
Dft Method ◽  
Basis Set ◽  
Hybrid Function ◽  
Calculation Results ◽  
The Difference ◽  
Solvent Molecules ◽  
The Relationship

This study aims to determine the amount of energy, the difference in energy, the relationship between the amount of energy and the distance between compounds, and the interactions that occur in organic solvent molecules using computational chemistry methods. In determining the amount of energy and interactions that occur, computational chemistry calculations are used using NWChem software version 6.6 with the DFT method with the B3LYP hybrid function/basis set 6-31G, the calculation results are visualized using Jmol software. The results of calculations with large computations of energy for benzene are -230.62447487 KJ/mol, ethanol -154.01322923 KJ/mol, methanol -114.98816558 KJ/mol, hexane are -235.27001385 KJ/mol. Mixture of benzene and ethanol in a ratio of 1 : 1 -384.63823964 KJ/mol, 1 : 2 538.66009762 KJ/mol , and 2 : 1 - 615.26607558 KJ/mol. A mixture of benzene and methanol in a ratio of 1 : 1 -345.61255299 KJ/mol, 1 : 2 - 460.60826254 KJ/mol, and 2 : 1 -576.24044425 KJ/mol, a mixture of hexane and ethanol in a ratio of 1 : 1 - 389.28477268 KJ/mol, 1 : 2 -543.29869234 KJ/mol and 2 : 1 -624.55723290 KJ/mol. A mixture of hexane and methanol at a ratio of 1 : 1 -350.25984691 KJ/mol, 1 : 2 -465.26041654 KJ/mol and 2 : 1 -585.53373886 KJ/mole. The difference in energy is the most in a mixture of benzene and ethanol in a ratio of 1 : 2 -0.00916429 K /mol, in a mixture of benzene and methanol in a ratio of 1 : 2 - 0.00745651 KJ/mol, a mixture of hexane and ethanol in a ratio of 2 : 1 -0.00397597 KJ/mol, and a mixture of hexane and methanol in a ratio of 1 : 2 - 0.01407153 KJ/mol. and there is no relationship between the magnitude of the interaction energy of the mixture with the distance between the molecules.

scholarly journals Modeling of neotame and fructose thermochemistry: Comparison with mono and divalent metal ions by Computational and experimental approach

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Deepali Sharma ◽  
Suvardhan Kanchi ◽  
Ayyappa Bathinapatla ◽  
Inamuddin ◽  
Abdullah M. Asiri
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Density Functional ◽  
Divalent Metal ◽  
Basis Set ◽  
Hydroxyl Groups ◽  
Specific Cell ◽  
Water Medium ◽  
Artificial Sweetener ◽  
Divalent Metal Ions

AbstractThe metal complexes can demonstrate various interesting biological activities in the human body. However, the role of certain metal ions for specific cell activities is still subject to debate. This study is aimed at comparing the thermochemical properties of neotame (artificial sweetener) and α, β-fructose in gas phase and water medium. The interaction of α and β-fructose, neotame with monovalent and divalent metal ions was studied and comprehended by density functional theory (DFT) using B3LYP functional, 6–311 + G (d, p) and D3 basis set. Metal ion affinities (MIA) values depicted that ionic radius of metal ions played an important role in the interaction of α, β-fructose and neotame. The ∆G parameter was calculated to predict and understand the interaction of metal ions with α and β-fructose, neotame. The results suggested that the presence of hydroxyl groups and oxygen atoms in sugar molecules acted as preferred sites for the binding and interaction of mono and divalent ions. For the first time computational study has been introduced in the present study to review the progress in the application of metal binding with sugar molecules especially with neotame. Moreover, voltammetric behaviour of neotame-Zn2+ was studied using cyclic and differential pulse voltammetry. The obtained results suggest that the peak at −1.13 V is due to the reduction of Zn2+ in 0.1 M phosphate buffer medium at pH 5.5. Whereas, addition of 6-fold higher concentration of neotame to the ZnCl2.2H2O resulted in a new irreversible cathodic peak at −0.83, due to the reduction of neotame-Zn2+ complex. The Fourier transform infrared spectroscopy (FTIR) results indicates that the β-amino group (-NH) and carboxyl carbonyl (-C = O) groups of neotame is participating in the chelation process, which is further supported by DFT studies. The findings of this study identify the efficient chelation factors as major contributors into metal ion affinities, with promising possibilities to determine important biological processes in cell wall and glucose transmembrane transport.

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