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Journal articles on the topic 'Density Functional Theory - DFT/B3LYP'

Author: Grafiati
Published: 4 June 2021
Last updated: 3 February 2022

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1

Adole, Vishnu A., Tejendra R. Rajput, and Bapu S. Jagdale. "Synthesis, Molecular Structure, HOMO-LUMO, Chemical, Spectroscopic (UV-Vis and IR), Thermochemical Study of Ethyl 6-amino-5-cyano-2-methyl-4-(4-nitrophenyl)-4H-pyran-3-carboxylate: A DFT Exploration." Material Science Research India 18, no. 2 (August 30, 2021): 179–89. http://dx.doi.org/10.13005/msri/180206.

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The ethyl 6-amino-5-cyano-2-methyl-4-(4-nitrophenyl)-4H-pyran-3-carboxylate (ACNPPC) was synthesized using an environmentally friendly method and looked into in terms ofstructural, UV-visible, vibrational, and computational analysis. In the gaseous phase, calculations of the density functional theory (DFT) with B3LYP/6-311G(d,p) level were performed. Using Time-dependent density functional theory (TD-DFT) with the B3LYP/6-311G(d,p) basis set method, the HOMO and LUMO energies are calculated. For assessing electrophilic and nucleophilic reactive sites, the molecular electrostatic surface potential (MESP) and contour plot were plotted over the optimized structure. Using computed and experimental vibrational spectra, vibrational assignments were elucidated. To illustrate the charge density in the title compound, Mulliken atomic charges are disclosed. In addition, using vibrational analysis, some thermochemical functions have also been derived. Theoretical simulations have shown the best relationship with experimental results obtained with the B3LYP/6-311G(d,p) level of theory at the DFT and TD-DFT methods.
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2

Pandey, Anoop Kumar, Shamoon Ahmad Siddiqui, Apoorva Dwivedi, Kanwal Raj, and Neeraj Misra. "Density functional theory study on the molecular structure of loganin." Spectroscopy 25, no. 6 (2011): 287–302. http://dx.doi.org/10.1155/2011/361849.

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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.
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3

Shahangi, Fereshte, Alireza Najafi Chermahini, Hossein Farrokhpour, and Abbas Teimouri. "Selective complexation of alkaline earth metal ions with nanotubular cyclopeptides: DFT theoretical study." RSC Advances 5, no. 3 (2015): 2305–17. http://dx.doi.org/10.1039/c4ra08302d.

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The interaction of alkaline earth metal cations including Be2+, Mg2+, Ca2+, Sr2+ and Ba2+ with cyclic peptides containing 3 or 4 (S) alanine molecules (CyAla3 and CyAla4) was investigated by density functional theory (DFT-CAM-B3LYP and DFT-B3LYP).
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4

Sarojini, K., H. Krishnan, Charles C. Kanagam, and S. Muthu. "Molecular Structure, Vibrational Spectroscopy and Homo, Lumo Studies of 4-methyl-N-(2-methylphenyl) Benzene Sulfonamide Using DFT Method." Advanced Materials Research 665 (February 2013): 101–11. http://dx.doi.org/10.4028/www.scientific.net/amr.665.101.

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The sulfonamide compound, 4-methyl-N-(2-methylphenyl) benzene sulfonamide has been synthesized and characterized by FTIR, NMR, UV-Vis, single crystal X-ray diffraction and thermal analysis. Density functional (DFT) calculations have been carried out for the title compound by performing DFT level of theory using B3LYP/6-31G (d,p) basis set. The calculated results show that the predicted geometry can well reproduce the structural parameters. Predicted vibrational frequencies have been assigned and compared with the experimental IR spectra and they support each other. In addition, atomic charges, frontier molecular orbitals and molecular electrostatic potential were carried out by using density functional theory (DFT/B3LYP) 6-31G (d, p) basis set. The calculated Homo and Lumo energies show that charge transfer occur in the molecule.
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5

Brahim, Sefia, Houari Brahim, Stéphane Humbel, and Ali Rahmouni. "Computational studies of Ni(II) photosensitizers complexes containing 1,1′-bis(diphenylphosphino)ferrocene and dithio ligands." Canadian Journal of Chemistry 98, no. 4 (April 2020): 194–203. http://dx.doi.org/10.1139/cjc-2019-0168.

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Detailed theoretical studies of Ni(II) complexes in a distorted square planar form and containing dithio and (P, P) chelating ligands were performed. These Ni(II) complexes are investigated for their use in dye-sensitized solar cells (DSSC). Structures and UV–vis spectra are calculated at density functional theory (DFT) and time-dependent density functional theory (TD-DFT) theories using B3LYP and CAM-B3LYP functionals and 6-31G(d,p) and 6-31G+(d) basis sets. Geometry optimizations result in excellent agreement with the experimental results. Moreover, the analysis of the frontier molecular orbitals (FMOs) allowed a detailed assignment and a clear analysis of the electronic transitions. The TD-DFT calculations reproduce the main spectroscopic properties observed and substituent effects. The results reveal that all absorption spectra are characterized by mixed character mainly dominated by metal to ligand and ligand to ligand charge transfers (MLCT and LLCT). We unveil how the substituent variations affect the DSSCs features of the complexes.
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6

ZHANG, ZHI-HUI, TAO GAO, XIAO-FENG TIAN, and NA HE. "THERMOCHEMICAL PROPERTIES OF THE THIOCARBONYLTHIO COMPOUNDS FROM CONVENTIONAL DENSITY FUNCTIONAL THEORY CALCULATIONS." Journal of Theoretical and Computational Chemistry 09, supp01 (January 2010): 201–17. http://dx.doi.org/10.1142/s0219633610005542.

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Density functional theory (DFT) calculations employed at two levels, B3LYP/6-31G+(d) and B3P86/6-31G+(d), are reported for the geometry, enthalpy, and free energy of reaction of a number of dithiobenzoate reversible addition fragmentation transfer (RAFT) reagents ( S=C(Ph)S–R , S=C(Z)S–CH2Ph ). Based on these theoretical data, the effectiveness of these RAFT reagents is analyzed. The conclusions, especially obtained at B3LYP/6-31G+(d) level, are in good agreement with the experimental results. Our calculations suggest that the dithiobenzoate ( S=C(Z)S–CH2Ph ), where Z is OC6H5 or N(alkyl)2 , is a poor RAFT reagent. Contrarily, the compound S=C(Ph)S–R , where R is C(Me)2Ph or C(Me)2CN , is a highly efficient RAFT reagent. Our results reveal the utility of the theoretical calculations of physical magnitudes for the rationalization of judging the effectiveness of RAFT reagents and demonstrated that DFT is a good method to calculate these data. In addition, our results on the enthalpies and Gibbs free energies of formation for the R radicals are calculated with the same method. These data are important for the design of logical and economical chemical process. Finally, the B3LYP hybrid functional is employed to predict the values of thermodynamic magnitudes for several new ithiobenzoates. Those results need to be verified by future experimental measurements or theoretical calculations.
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7

Turan, Haydar Taylan, Oğuzhan Kucur, Birce Kahraman, Seyhan Salman, and Viktorya Aviyente. "Design of donor–acceptor copolymers for organic photovoltaic materials: a computational study." Physical Chemistry Chemical Physics 20, no. 5 (2018): 3581–91. http://dx.doi.org/10.1039/c7cp08176f.

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80 different push–pull type organic chromophores which possess Donor–Acceptor (D–A) and Donor–Thiophene–Donor–Thiophene (D–T–A–T) structures have been systematically investigated by means of density functional theory (DFT) and time-dependent DFT (TD-DFT) at the B3LYP/6-311G* level.
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8

Ghasemi, Ashraf Sadat, Mahsan Deilam, and Fereydoun Ashrafi. "INVESTIGATION OF MOLECULAR STRUCTURE AND EXPERIMENTAL AND THEORETICAL SPECTROSCOPIC STUDIES OF ANTICANCER DRUGS - A REVIEW." Ciência e Natura 38, no. 2 (May 31, 2016): 1124. http://dx.doi.org/10.5902/2179460x21525.

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In many literatures, both experimental and computational study on molecular structure and spectroscopic assignments of anticancer drugs has been reported. The molecular geometry was obtained from the X-ray structure determination exprimentally and optimized using computational chemistry methods like Density Functional Theory (DFT) method. In this review, we have investigated calculations based on density functional theory at the B3LYP/6-31G(d,p) and B3LYP/6-311++G(d,p) levels of theory. From the optimized geometry of the molecules, Molecular structure (bond lengths, bond angles and torsion angles) and vibrational assignments have been obtained.
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9

Nachtigallová, Dana, Markéta Davidová, and Petr Nachtigall. "Reliability of DFT Methods for Description of Cu Sites and Their Interaction with NO in Zeolites." Collection of Czechoslovak Chemical Communications 63, no. 8 (1998): 1202–12. http://dx.doi.org/10.1135/cccc19981202.

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The reliability of various DFT functionals for description of Cu sites and their interaction with NO in zeolites is tested. The dissociation energies of Cun+H2O and Cun+NO systems calculated with various DFT functionals are compared with those obtained at the MP2 and CCSD(T) levels of theory. It is concluded that hybrid density functional (B3LYP) gives reliable description of studied systems, while LDA seriously overestimates dissociation energies.
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10

A. Kadir, Laode. "Struktur dan Vibrasi Carbamida: Eksperimen dan Kajian Teoritik Density functional theory (DFT)." SAINTIFIK 6, no. 2 (August 10, 2020): 116–20. http://dx.doi.org/10.31605/saintifik.v6i2.266.

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Pada penelitian analisis spektrum vibrasi dilakukan menggunakan spektroskopi infra merah pada rentang 500-4000 cm-1 untuk molekul karbamida. Struktur molekul, frekuensi vibrasi dasar dan intensitas dan intensitas pita vibrasi diinterpretasikan dengan bantuan optimasi struktur dan perhitungan medan gaya koordinat normal berdasarkan metode density functional theory (DFT). Penugasan getaran yang lengkap dari bilangan gelombang dibuat pada dasar distribusi energi potensial. Hasil B3LYP/6-31G skala memperlihatkan kesesuaian dengan nilai ekperimen.
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11

Guo, Ying, Huaxin Zhu, Guofeng Yang, Guilin Liu, Hunmin Yan, Bingjie Zhu, Shuai Li, Yajun Sun, and Guohua Li. "Acceptors/linkers effects on dye sensitized solar cell: Theoretical investigations of structure-property relationship for design of efficient dye sensitizers." Journal of Theoretical and Computational Chemistry 13, no. 07 (November 2014): 1450062. http://dx.doi.org/10.1142/s021963361450062x.

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A series of carbazole-based organic dyes such as CzFCA, CzTCA, CzSeCA, CzFRA, CzTRA and CzSeRA with introduction of various linkers (furan, thiophene and selenophen) and acceptor (cyanoacrylic acid and rhodanine-3-acetic acid) groups, were designed and theoretically investigated by density functional theory (DFT) and time dependent DFT (TD-DFT). The ground state structures and absorption spectra (both in vacuum and solvated form) were optimized by using DFT-B3LYP/6-31G(d,p), TD-B3LYP/6-311G(d,p) and PCM-TD-B3LYP/6-311G(d,p) levels of theory. Substitution of linker groups from furan to selenophen, resulted in red-shift of absorption band. CzTRA and CzSeRA exhibited superior electron injection capabilities. The finding of this study can be helpful to obtain dye-sensitized solar cell (DSSC) with superior conversion efficiency.
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12

ZHA, DONG, LAI-CAI LI, YAN ZHENG, XIN WANG, AN-MIN TIAN, and NING-BEW WONG. "THEORETICAL STUDY OF THE HYDROLYSIS MECHANISM OF METABOLIC PRODUCT FROM TIRAPAZAMINE'S UNDERGOING ENZYMATIC CATALYSIS." Journal of Theoretical and Computational Chemistry 05, no. 02 (June 2006): 235–42. http://dx.doi.org/10.1142/s0219633606002143.

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Two different hydrolysis mechanisms of metabolic product from tirapazamine's enzymatic catalysis have been studied by density functional theory (DFT) at the B3LYP/6-31G(d) and B3LYP/6-311+G(d) levels. The results indicate that the activation barrier of rate-controling step of Brown's model is smaller than that of Denny's model.
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13

Shakila, G., S. Periandy, and S. Ramalingam. "Molecular Structure and Vibrational Analysis of 1-Bromo-2-Chlorobenzene Using ab initio HF and Density Functional Theory (B3LYP) Calculations." Journal of Atomic, Molecular, and Optical Physics 2011 (August 11, 2011): 1–10. http://dx.doi.org/10.1155/2011/512841.

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The FT-Raman and FT-IR spectra for 1-bromo-2-chlorobenzene (1B2CB) have been recorded in the region 4000–100 cm−1 and compared with the harmonic vibrational frequencies calculated using HF/DFT (B3LYP) method by employing 6-31+G (d, p) and 6-311++G (d, p) basis set with appropriate scale factors. IR intensities and Raman activities are also calculated by HF and DFT (B3LYP) methods. Optimized geometries of the molecule have been interpreted and compared with the reported experimental values of some substituted benzene. The experimental geometrical parameters show satisfactory agreement with the theoretical prediction from HF and DFT. The scaled vibrational frequencies at B3LYP/6-311++G (d, p) seem to coincide with the experimentally observed values with acceptable deviations. The theoretical spectrograms (IR and Raman) have been constructed and compared with the experimental FT-IR and FT-Raman spectra. Some of the vibrational frequencies of the benzene are affected upon profusely with the halogen substitutions in comparison to benzene, and these differences are interpreted.
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14

Siddiqui, Shamoon Ahmad, Tabish Rasheed, Mohd Faisal, Anoop Kumar Pandey, and Sher Bahadar Khan. "Electronic Structure, Nonlinear Optical Properties, and Vibrational Analysis of Gemifloxacin by Density Functional Theory." Spectroscopy: An International Journal 27 (2012): 185–206. http://dx.doi.org/10.1155/2012/614710.

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The non-linear optical properties of gemifloxacin (C18H20FN5O4) have been examined using density functional theory (DFT). The molecular HOMO, LUMO composition, their respective energy gaps, MESP contours/surfaces have also been drawn to explain the activity of gemifloxacin. The equilibrium geometries and harmonic frequencies of title molecule was determined and analyzed at DFT/B3LYP level employing the 6-31G(d,p) basis set. The skeleton of both the optimized molecules is non-planar. In general, a good agreement between experimental and calculated normal modes of vibrations has been observed.
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15

Saiz, Fernan, and Nick Quirke. "The excess electron in polymer nanocomposites." Physical Chemistry Chemical Physics 20, no. 43 (2018): 27528–38. http://dx.doi.org/10.1039/c8cp04741c.

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We have used ab initio molecular dynamics and density-functional theory (DFT) calculations at the B3LYP/6-31G** level of theory to evaluate the energy and localisation of excess electrons at a number of representative interfaces of polymer nanocomposites.
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16

Guo, Feng, Hong Zhang, Chao-Yang Zhang, Xin-Lu Cheng, and Hai-Quan Hu. "Effect of electronic excitation to intermolecular proton transfer in bulk nitromethane: Tuned parameter SCC-DFTB and first principles study." Journal of Theoretical and Computational Chemistry 14, no. 02 (March 2015): 1550013. http://dx.doi.org/10.1142/s0219633615500133.

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To understand the reaction mechanism involving hydrogen transfers through hydrogen-bond bridge, we carried out both Self-Consistent Charge Density Functional Tight-Binding (SCC-DFTB) calculations of bulk nitromethane and Density Functional Theory (DFT) calculations of singlet ground state/triplet excited state molecular nitromethane using B3LYP functional. Firstly, we tuned the repulsive parameters of the SCC-DFTB method for nitromethane with dataset calculated from DFT at B3LYP/6-311g level. The molecular dynamics simulations are carried out with tuned parameters to get the dynamical properties of the bulk nitromethane, and the static calculations are intended to give energy profile of the reaction process. These calculations indicate the excitation of nitromethane molecule making the proton transfer reactions possible, and lowering the reaction barrier.
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17

Hou, Li-Jie, Bo-Wan Wu, Yan-Xia Han, Chao Kong, Dong-Ping Chen, and Li-Guo Gao. "Density functional theoretical study on the reaction mechanism of SiHF radical with HNCO." Journal of Theoretical and Computational Chemistry 13, no. 07 (November 2014): 1450054. http://dx.doi.org/10.1142/s0219633614500540.

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The reaction mechanism of SiHF radical with HNCO has been investigated by the B3LYP method of density functional theory (DFT), while the geometries and harmonic vibration frequencies of reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311++G** level. To obtain more precise energy result, stationary point energies were calculated at the CCSD(T)/6-311++G**//B3LYP/6-311++G** level. In temperature range of 100 K to 1900 K, the statistical thermodynamics and Eyring transition state theory with Winger correction are used to study the thermodynamic and kinetic characters of the channel with low energy barrier at 1.0 Atm. SiHF + HNCO → IM 8 → TS 8 → SiFNHCHO ( P 3) was the main channel with low potential energy in the singlet state, SiFNHCHO was the main product. The analyses for the combining interaction between SiHF radical and HNCO with the atom-in-molecules (AIM) theory have been performed. There are three reaction channels in the triplet.
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18

Avcı, Davut, Adil Başoğlu, and Yusuf Atalay. "Density Functional Theory and ab initio Hartree-Fock Calculations of Molecular Structure and Vibrational Spectra of Anilinium Nitrate." Zeitschrift für Naturforschung A 63, no. 10-11 (November 1, 2008): 712–20. http://dx.doi.org/10.1515/zna-2008-10-1115.

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The molecular geometry, vibrational frequencies, infrared intensities, Raman scattering activities and several thermodynamic parameters of anilinium nitrate in the ground state have been calculated by both Hartree-Fock (HF) and three density functional theory (DFT) methods (B3LYP, BLYP and B3PW91) using the 6-31G(d) basis set. The results of the optimized molecular structure are presented and compared with the experimental X-ray structure. The optimized geometric bond lengths are described very well by the HF method while bond angles are reproduced more accurately by the DFT methods. Comparison between the observed fundamental vibrational frequencies of anilinium nitrate and the results of DFT and HF methods indicates that B3LYP is superior to the scaled HF, BLYP and B3PW91 approaches for molecular vibrational problems. The computed vibrational frequencies are used to determine the types of molecular motions associated with each of the experimental bands observed. In addition, calculated results are related to the linear correlation plot of computed data versus experimental geometric parameters and IR data.
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19

Maxwell, Peter, Ángel Martín Pendás, and Paul L. A. Popelier. "Extension of the interacting quantum atoms (IQA) approach to B3LYP level density functional theory (DFT)." Physical Chemistry Chemical Physics 18, no. 31 (2016): 20986–1000. http://dx.doi.org/10.1039/c5cp07021j.

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20

Maroulis, George, and Constantine Makris. "Static Dipole Polarizability and Hyperpolarizability of F2 from Density Functional Theory Calculations. Similarities and Dissimilarities with Conventional ab initio Results." Computing Letters 2, no. 3 (March 6, 2006): 131–38. http://dx.doi.org/10.1163/157404006778330825.

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We have calculated the bond-length dependence of the static dipole polarizability and hyperpolarizability of F2 relying on finite-field density functional calculations. At the internuclear separation of Re = 2.66816 a0 we obtain α/ e2a0 2Eh-1 = 8.73 (B3LYP) and 8.60 (B3PW91),α./ e2a0 2Eh-1 = 6.42 (B3LYP) and 6.32 (B3PW91), γ / e4a04Eh-3 = 535 (B3LYP) and 503 (B3PW91) with a large, flexible [9s6p4d1f] basis set. For all three properties we observe that both B3LYPand B3PW91 yield values above the more accurate CCSD(T) results: CCSD(T) < B3PW91 < B3LYP. The discrepancy between DFT and conventional ab initio methods is more pronounced for the anisotropy of the (hyper)polarizability.
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21

Eşme, A., S. G. Sagdinc, and Y. S. Kara. "Experimental and theoretical study of the substituent type and position effects on 3-(substituted phenyl)-cis-4,5-dihydroisoxazole- 4,5-diyl)bismethylene)diacetate derivatives." Журнал структурной химии 62, no. 6 (2021): 934–44. http://dx.doi.org/10.26902/jsc_id72862.

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Effects of the substituent type and the position (X = -H, -p-CH3, -p-C2H5, -p-CF3, -p-Br, -p-Cl, -p-CN, -m-F, -m-NO2) on 3-(substituted phenyl)-cis-4,5-dihydroisoxazole-4,5-diyl)bis(methy­lene)diacetate derivatives are investigated experimentally FTIR and UV-Vis and theoretically using the density functional theory (DFT) at the B3LYP/6-311G(d,p) level of theory. The influence of these substituents on the frontier molecular orbital analysis of the investigated series is discussed using DFT. The absorption spectra (UV-Vis spectra) of all the derivatives in the gas phase and the chloroform solvent simulated using the time-dependent density functional theory (TD-DFT) are compared with those obtained experimentally.
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22

Nisa, Riffat Un, Maria Maria, Fatima Wasim, Tariq Mahmood, Ralf Ludwig, and Khurshid Ayub. "Mechanistic insight of TiCl4catalyzed formal [3 + 3] cyclization of 1,3-bis(silyl enol ethers) with 1,3-dielectrophiles." RSC Advances 5, no. 114 (2015): 94304–14. http://dx.doi.org/10.1039/c5ra19238b.

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The mechanism of TiCl4mediated formal [3 + 3] cyclization of 1,3-bis(silyl enol ethers) with 1,3-dielectrophiles is studied at the B3LYP level of density functional theory (DFT) to rationalize the experimental regioselectivity.
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23

Cao, Bo, Zhigang Gai, Li Yang, Jie Zhao, and Shibo Chu. "Density functional study on Si2CmN (m = 2–10) clusters." Canadian Journal of Chemistry 91, no. 3 (March 2013): 226–28. http://dx.doi.org/10.1139/cjc-2012-0185.

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Structures, vibrational frequencies, and energies of Si2CmN (m = 2–10) clusters have been investigated using the B3LYP density functional theory (DFT) method with a 6-311G* basis set. The character of the chemical bond and thermodynamic stability of isomers has been discussed. The results show that all Si2CmN (m = 2–10) clusters form linear structures, which are in doublet states. Si atoms favor bonding to the ends of C and N linear chains. The clusters with an even m are more stable.
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24

Pal, Snehanshu, and T. K. Kundu. "Theoretical Study of Hydrogen Bond Formation in Trimethylene Glycol-Water Complex." ISRN Physical Chemistry 2012 (November 28, 2012): 1–12. http://dx.doi.org/10.5402/2012/570394.

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A detailed quantum chemical calculation based study of hydrogen bond formation in trimethylene glycol- (TMG-) water complex has been performed by Hatree-Fock (HF) method, second-order Møller-Plesset perturbation theory (MP2), density functional theory (DFT), and density functional theory with dispersion function (DFT-D) using 6-31++G(d,p) basis set. B3LYP DFT-D, WB97XD, M06, and M06-2X functionals are used to capture highly dispersive hydrogen bond formation. Geometrical parameters, interaction energy, deviation of potential energy curve of hydrogen-bonded O–H from that of free O–H, natural bond orbital (NBO), atom in molecule (AIM), charge transfer, and red shift are investigated. It is observed that hydrogen bond between TMG and water molecule is stronger in case of TMG acting as proton donor compared to that of water acting as proton donor, and dilute TMG solution would inhibit water cluster formation.
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25

Saputra, Andrian, Karna Wijaya, Ria Armunanto, Lisa Tania, and Iqmal Tahir. "Determination of Effective Functional Monomer and Solvent for R(+)-Cathinone Imprinted Polymer Using Density Functional Theory and Molecular Dynamics Simulation Approaches." Indonesian Journal of Chemistry 17, no. 3 (November 30, 2017): 516. http://dx.doi.org/10.22146/ijc.24311.

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Determination of effective functional monomer and solvent for R(+)-cathinone imprinted polymer through modeling has been done using density functional theory (DFT) and molecular dynamics (MD) simulation approaches. The selection criteria of the best monomer and solvent are based on the classical potential energy (ΔEMM) from molecular dynamics simulation and confirmed further by quantum potential energy (ΔEDFT) from DFT calculation. The DFT calculation was performed in B3LYP exchange-correlation functional within the 6-31G(d) basis set of function including Polarizable Continuum Model (PCM) solvation effect. From this research, it is obtained that N,N’-methylene bis acrylamide and chloroform are respectively the best candidates for effective functional monomer and solvent, for the synthesis of R(+)-cathinone imprinted polymer.
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Zhang, Yanli, Jieqiong Li, and Li Wang. "Effect of principal and secondary ligands on the electronic structures and spectra of a series of ruthenium(II) complexes." Journal of the Serbian Chemical Society 81, no. 5 (2016): 521–39. http://dx.doi.org/10.2298/jsc151029031z.

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A DFT(density functional theory)/TDDFT(time-dependent density functional theory) investigation is performed to study the ground-state geometries, electronic structures, and absorption spectra of twelve ruthenium(II) thiosemicarbazone complexes [Ru(CO)(C)(Ln)], where Ln=derivatives of dibasic tetradentate Schiff-base ligand and X=AsPh3/PPh3/Py. The ground-state geometries are optimized at the B3LYP/6-31G(d)-LANL2DZ level, and the spectra are simulated by means of TD-B3LYP/6-31G(d)-LANL2DZ method on the basis of the optimized geometries. The influence of principal and secondary ligands (Ln and X) on transition characters and absorption peak positions is evaluated.
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27

Avci, Davut, and Semiha Bahceli. "Quantum chemical insight into molecular structure, spectroscopic and nonlinear optical studies on methylene bis(dithiobenzoate)-=SUP=-*-=/SUP=-." Оптика и спектроскопия 129, no. 9 (2021): 1136. http://dx.doi.org/10.21883/os.2021.09.51338.1060-21.

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In this study, the methylene bis(dithiobenzoate) molecule, (C15H12S4), as a bioactive molecule has been subjected to quantum chemical computations using density functional theory (DFT) in order to investigate the molecular geometry, IR, UV-visible and NMR spectral studies. The title molecule has been optimized at the B3LYP, B3PW91 and PBE11PBE levels of DFT and 6-311G(d,p) basis set. Furthermore, the vibrational frequencies, the HOMO-LUMO energy levels, the 1H and 13C NMR chemical shifts (ppm), nonlinear optical properties calculations of the title compound were obtained by B3LYP, B3PW91 and PBE1PBE levels. The maximum electronic transition wavelengths, oscillator strengths, excited state and transition dipole moments for the title compound were also investigated by B3LYP, B3PW91 and PBE1PBE levels of time-dependent (TD)-DFT. Keywords: methylene bis(dithiobenzonoate), IR and UV-vis spectroscopy, 1H and 13C NMR chemical shifts, NLO DFT method.
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28

Gong, Liangfa, Jieming Xiong, Xinmin Wu, Chuansong Qi, Wei Li, and Wenli Guo. "Density Functional Study of Structures and Electron Affinities of BrO4F/BrO4F-." International Journal of Molecular Sciences 10, no. 7 (July 8, 2009): 3128–48. http://dx.doi.org/10.3390/ijms10073128.

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The structures, electron affinities and bond dissociation energies of BrO4F/BrO4F− species have been investigated with five density functional theory (DFT) methods with DZP++ basis sets. The planar F-Br…O2…O2 complexes possess 3A' electronic state for neutral molecule and 4A' state for the corresponding anion. Three types of the neutral-anion energy separations are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). The EAad value predicted by B3LYP method is 4.52 eV. The bond dissociation energies De (BrO4F → BrO4-mF + Om) (m = 1-4) and De- (BrO4F- → BrO4-mF- + Om and BrO4F- → BrO4-mF + Om-) are predicted. The adiabatic electron affinities (EAad) were predicted to be 4.52 eV for F-Br…O2…O2 (3A'← 4A') (B3LYP method).
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29

Punyain, Wikorn. "A DFT Investigation of the Molecular Structure and UV Absorption Spectra of 2-Ethylhexyl 2-Hydroxybenzoate (Octisalate) and Meta-Substituted 2-Ethylhexyl 2-Hydroxybenzoate: Sunscreen Applications." Applied Mechanics and Materials 855 (October 2016): 15–21. http://dx.doi.org/10.4028/www.scientific.net/amm.855.15.

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2-ethylhexyl 2-hydroxybenzoate (octisalate) is one of organic compounds containing in sunscreen products to absorb ultraviolet radiation. Density Functional Theory (DFT) was used to investigate the molecular structure and the ultraviolet (UV) absorption spectrum of 2-ethylhexyl 2-hydroxybenzoate and meta-substituted 2-ethylhexyl 2-hydroxybenzoate to model the novel sunscreen compounds. The geometry optimizations and frequency calculations were done at B3LYP/6-311++G(d,p) level of theory. The 10 vertical excitation calculations were performed by Time-Dependent Density Functional Theory (TD-DFT) at B3LYP/6-311++G(d,p) level. The solvent effects were taken into account by using the Polarizable Continuum Model (CPCM). It was found that the intramolecular hydrogen bond occurred in the 2-ethylhexyl 2-hydroxybenzoate structure. The UV absorption spectrum in the UVA and UVB regions are π→π* transitions (HOMO→LUMO transitions). The calculated UV absorption spectrum of the 2-ethylhexyl 2-hydroxybenzoate and its derivatives are significantly affected by the substitution groups.
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30

Zhu, Wei-Liang, Xiao-Jian Tan, Chum Mok Puah, Jian-De Gu, Hua-Liang Jiang, Kai-Xian Chen, Clifford E. Felder, Israel Silman, and Joel L. Sussman. "How Does Ammonium Interact with Aromatic Groups? A Density Functional Theory (DFT/B3LYP) Investigation." Journal of Physical Chemistry A 104, no. 42 (October 2000): 9573–80. http://dx.doi.org/10.1021/jp001306v.

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31

Zhang, Cai-Rong, Li-Heng Han, Jian-Wu Zhe, Neng-Zhi Jin, Yu-Lin Shen, Li-Hua Yuan, You-Zhi Wu, and Zi-Jiang Liu. "Electronic Structures and Optical Properties of Phenyl C71Butyric Acid Methyl Esters." Journal of Nanomaterials 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/612153.

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Phenyl C71butyric acid methyl ester (PC71BM) has been adopted as electron acceptor materials in bulk heterojunction solar cells with relatively higher power conversion efficiency. The understanding of the mechanism and performance for the devices based upon PC71BM requires the information of conformations, electronic structures, optical properties, and so forth. Here, the geometries, IR and Raman, electronic structures, polarizabilities, and hyperpolarizabilities of PC71BM isomers are studied by using density functional theory (DFT); the absorption and excitation properties are investigated via time-dependent DFT with B3LYP, PBE0, and CAM-B3LYP functionals. The calculated results show that [6,6]PC71BM is more stable than [5,6]PC71BM due to the lower total energy. The vibrational modes of the isomers at IR and Raman peaks are quite similar. As to absorption properties, CAM-B3LYP functional is the suitable functional for describing the excitations of PC71BM because the calculated results with CAM-B3LYP functional agree well with that of the experiment. The analysis of transition configurations and molecular orbitals demonstrated that the transitions at the absorption maxima in UV/Vis region are localizedπ-π*transitions in fullerenes cages. Furthermore, the larger isotropic polarizability of PC71BM indicates that the response of PC71BM to applied external electric field is stronger than that of PC61BM, and therefore resulting into better nonlinear optical properties.
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32

Toh, Pek Lan, Montha Meepripruk, and Rosfayanti Rasmidi. "A Computational Study on Structural and Electronic Properties of 1-(4-Chlorophenyl)-2-{[5-(4-Chlorophenyl)-1,2,3-Oxadiazol-2-Yl]Sulfanyl}Ethanone." Applied Mechanics and Materials 892 (June 2019): 1–7. http://dx.doi.org/10.4028/www.scientific.net/amm.892.1.

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In this paper, a first principle Density Functional Theory (DFT) method was conducted to study the geometric and electronic structures of 1-(4-chlorophenyl)-2-{[5-(4-chlorophenyl) -1,3,4-oxadiazol-2-yl] sulfanyl} ethanone, C16H10Cl2N2O2S. Using B3LYP level of theory with four basis sets of 6-31G**, 6-31++G**, 6-311G**, and 6-311++G**, the equilibrium structure of the title molecule was used to determine the total energies, Frontier molecular orbital’s energies, Mulliken atomic charges, and others. The computed findings present that four total energies obtained are close to each other, with the corresponding values of-59716.06 eV, -59709.42 eV, -59708.56 eV, and-59716.51 eV, respectively for B3LYP/6-31G**, B3LYP/6-31++G**, B3LYP/6-311G**, and B3LYP/6-311++G** methods. The calculated HOMO-LUMO energy gaps were predicted in the range of 4.001 eV - 4.089 eV. In this study, the atomic charge values of molecular system were also determined using Mulliken Population Analysis (MPA) approach. For DFT/B3LYP/6-311G** level of calculation, the computed results show that the atom of C8 accommodates the highest negative charge in the title molecular system. All the oxygen, nitrogen, and chloride atoms are having negative charges, whereas all the hydrogen atoms are having positive charges. In addition, the dipole moment value was also determined to be 1.4758 Debye by employing DFT/B3LYP/6-311G** level of theory.
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33

Pavelka, Laura C., Margaret A. Hanson, Viktor N. Staroverov, and Kim M. Baines. "Mechanism of the addition of alkynes to silenes and germenes: A density functional study." Canadian Journal of Chemistry 93, no. 1 (January 2015): 134–42. http://dx.doi.org/10.1139/cjc-2014-0256.

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Density functional theory (DFT) and the coupled cluster method have been used to study the mechanism of the cycloaddition of acetylene to silene, H2Si=CH2, and germene, H2Ge=CH2, at the B3LYP/6-311++G(d,p) and CCSD/6-311++G(d,p) levels of theory. Diradical, zwitterionic, and concerted pathways were located for both metallenes. The computational results were compared to experimental data to propose the most likely reaction pathway for each metallene.
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34

Jonas, Patrick F., and Geoffrey A. Cordell. "Molecular Modeling, NOESY NMR, and the Structure of Nicandrenone Isolated from Nicandra Physalodes (Solanaceae)." Natural Product Communications 4, no. 6 (June 2009): 1934578X0900400. http://dx.doi.org/10.1177/1934578x0900400609.

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The configuration and conformation of nicandrenone, isolated from Nicandra physalodes, are described using molecular modeling and NMR NOESY techniques. Amsterdam Density Functional (ADF) software was used, and the structures were those reduced to minimum energy molecular models, utilizing B3LYP executions and Density Functional Theory (DFT). The first spectral proof that this withanolide has a 22-R configuration is also provided. This method may be adaptable to other natural products.
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35

Shao, Ting Ting, Fu Chun Zhang, and Wei Hu Zhang. "First Principles Studies on Structural, Electronic and Optical Properties of SnO2." Advanced Materials Research 900 (February 2014): 203–8. http://dx.doi.org/10.4028/www.scientific.net/amr.900.203.

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The structural, electronic, and optical properties of rutile-type SnO2 are studied by plane-wave pseudopotential density functional theory (DFT) with GGA, LDA, B3LYP and PBE0 respectively. The computing results show that the band gap getting from PBE0 and B3LYP is much more consistent with the available experimental data than that from GGA and LDA, no matter what the latter use ultra-soft pseudopotential or norm conserving pseudopotential. However, the density of state, real part and imaginary part of dielectric function calculating from every type is basically similar in qualitative analysis.
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36

Pei, Hui Yi, Ai Fang Gao, and Zhen Ya Zhu. "The DFT Quantum Chemistry Study of Hexafluorobenzene." Advanced Materials Research 610-613 (December 2012): 106–10. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.106.

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The molecular structures, electron affinities, and dissociation energies of the C6F6molecule have been determined using seven hybrid and pure density functional theory (DFT) methods and the DZP++ basis set. Three different types of the neutral-anion energy separations reported in this work are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). The most reliable adiabatic electron affinities, obtained at the B3PW91 and B3LYP levels, are 0.59 and 0.69 eV, respectively. The first dissociation energies De(C6F5-F) for the neutral C6F6predicted by the DFT methoSubscript textds except BHLYP are 5.195.44 eV. Compared with the limited experimental dissociation energies, our theoretical predictions of the B3LYP and B3PW91 methods are fairly reasonable.
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37

Lai, Chin-Hung, Chia-Chin Chang, Yi-Lin Weng, and Ta-Hsien Chuang. "Synthesis, Experimental and Density Functional Theory (DFT) Studies on Solubility of Camptothecin Derivatives." Molecules 23, no. 12 (December 1, 2018): 3170. http://dx.doi.org/10.3390/molecules23123170.

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Two camptothecin derivatives, 10-cyclohexyl-7-methyl-20(S)-camptothecin and 7-methyl-10-morpholino-20(S)-camptothecin, were synthesized and their differences in solubility were investigated using four chosen solvent systems. Based on our results, 10-cyclohexyl-7-methyl-20(S)-camptothecin exhibited higher solubilities than 7-methyl-10-morpholino-20(S)-camptothecin in polar aprotic solvents. However, these two camptothecin derivatives did not exhibit apparent differences in solubility between 5% dimethyl sulfoxide (DMSO)/95% normal saline co-solvent system and 5% dimethylacetamide (DMAC)/95% normal saline co-solvent system. To rationalize their differences in solubility, we also tried to perform a DFT-B3LYP study to investigate their interaction with one water molecule.
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38

Nguyen Phan, Truc Xuyen. "A DENSITY FUNCTIONAL THEORY STUDY OF ANTIOXIDANT ACTIVITY OF ISOTHIOCYANATES IN BROCCOLI SPROUTS (BRASSICA OLERACEA L.)." Vietnam Journal of Science and Technology 54, no. 2C (March 19, 2018): 306. http://dx.doi.org/10.15625/2525-2518/54/2c/11851.

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Antioxidant activity of 9 isothiocyanate derivatives (−N=C=S) extracted from Broccolisprouts (Brassica oleracea L.) has been investigated using density functional theory (DFT) –based computational methods. Through the hydrogen atom transfer (HAT) and single electrontransfer (SET) mechanisms, three thermodynamic parameters including bond dissociationenthalpy (BDE), vertical ionization energy (IE), and vertical electron affinity (EA) werecalculated in the gas phase using B3LYP/6-311++G(3df,3p)//B3LYP/6-311G(d,p) modelchemistry. As a result, the isothiocyanate (ITC) shows potential antioxidant activity via HATmechanism. The most potential antioxidant is 3-isothiocyanato pro-1-en (3ITCP) withBDE(C−H) of 72.9 kcal/mol. The SET mechanism is not dominant in case of the studied ITCs.Moreover, the radicals formed H• removal had more reactive and less stable than the intialneutral compounds with lower IE, higher EA and ω.
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39

Han, May Win, Piyasiri Ekanayake, Lim Chee Ming, and Voo Nyuk Yoong. "DFT/TD-DFT Studies on the Lawsone (Henna) as a Photosensitizer for Dye-Sensitized Solar Cells." Applied Mechanics and Materials 789-790 (September 2015): 56–60. http://dx.doi.org/10.4028/www.scientific.net/amm.789-790.56.

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In this study, the parameters of the photo-electrochemical properties, such as the ground state geometries, excitation energy, electronic structures, optical properties and electronics transition of lawsone were investigated by using density functional theory ( DFT ) and time dependent - DFT with B3LYP/6-31G( d) method. The solvent effect was considered in the DFT calculations and compared with the value of vacuum. From the analyses of electronic and optical properties, it is found that the lawsone satisfy the condition for good conversion efficiency as DSSCs device.
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40

Journal, Baghdad Science. "Density functional theory study of molecular structure, Electronic properties, UV–Vis spectra on coumarin102." Baghdad Science Journal 13, no. 2 (June 5, 2016): 143–52. http://dx.doi.org/10.21123/bsj.13.2.143-152.

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The various properties of the ground and excited electronic states of coumarins 102 using density functional theory (DFT) and time-dependent density functional theory (TDDFT) was calculated by the B3LYP density functional model with 6-31G(d,p) basis set by Gaussian 09 W program. Spectral characteristics of coumarin102 have been probed into by methods of experimental UV-visible, and quantum chemistry. The UV spectrum was measured in methanol. The optimized structures, total energies, electronic states (HOMO- LUMO), energy gap, ionization potentials, electron affinities, chemical potential, global hardness, softness, global electrophilictity, and dipole moment were measured. We find good agreement between experimental data of UV spectrum and TDDFT excitationenergies.
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41

Adejumo, Temiloluwa T., Nikolaos V. Tzouras, Leandros P. Zorba, Dušanka Radanović, Andrej Pevec, Sonja Grubišić, Dragana Mitić, et al. "Synthesis, Characterization, Catalytic Activity, and DFT Calculations of Zn(II) Hydrazone Complexes." Molecules 25, no. 18 (September 4, 2020): 4043. http://dx.doi.org/10.3390/molecules25184043.

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Two new Zn(II) complexes with tridentate hydrazone-based ligands (condensation products of 2-acetylthiazole) were synthesized and characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy and single crystal X-ray diffraction methods. The complexes 1, 2 and recently synthesized [ZnL3(NCS)2] (L3 = (E)-N,N,N-trimethyl-2-oxo-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)ethan-1-aminium) complex 3 were tested as potential catalysts for the ketone-amine-alkyne (KA2) coupling reaction. The gas-phase geometry optimization of newly synthesized and characterized Zn(II) complexes has been computed at the density functional theory (DFT)/B3LYP/6–31G level of theory, while the highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO and LUMO) energies were calculated within the time-dependent density functional theory (TD-DFT) at B3LYP/6-31G and B3LYP/6-311G(d,p) levels of theory. From the energies of frontier molecular orbitals (HOMO–LUMO), the reactivity descriptors, such as chemical potential (μ), hardness (η), softness (S), electronegativity (χ) and electrophilicity index (ω) have been calculated. The energetic behavior of the investigated compounds (1 and 2) has been examined in gas phase and solvent media using the polarizable continuum model. For comparison reasons, the same calculations have been performed for recently synthesized [ZnL3(NCS)2] complex 3. DFT results show that compound 1 has the smaller frontier orbital gap so, it is more polarizable and is associated with a higher chemical reactivity, low kinetic stability and is termed as soft molecule.
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42

Shinde, Rohit S. "Ultrasound Assisted Synthesis, Molecular Structure,UV-Visible Assignments, MEP and Mulliken Charges Study of (E)-3-(4-chlorophenyl)-1-(4-methoxyphenyl) prop-2-en-1-one: Experimental and DFT Correlational." Material Science Research India 18, no. 1 (April 30, 2021): 86–96. http://dx.doi.org/10.13005/msri/180110.

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Present investigation deals with the synthesis and density functional theory study (DFT) of a chalcone derivative; (E)-3-(4-chlorophenyl)-1-(4-methoxyphenyl)prop-2-en-1-one (CPMPP). The synthesis of a CPMPP has been carried out by the reaction of 4-methoxyacetophenone and 4-chlorobenzalehyde in ethanol at 30 ℃ under ultrasound irradiation. The structure of a synthesized chalcone is affirmed on the basis of FT-IT, 1H NMR and 13C NMR. The geometry of a CPMPP is optimized by using the density functional theory method at the B3LYP/6-31G(d,p) basis set. The optimized geometrical parameters like bond length and bond angles have been computed. The absorption energies, oscillator strength, and electronic transitions have been derived at the TD-DFT method at the B3LYP/6-31G(d,p) level of theory for B3LYP/6-31G(d p) optimized geometries. The effect of polarity on the absorption energies is discussed by computing UV-visible results in dichloromethane (DCM). Since theoretically obtained wavenumbers are typically higher than experimental wavenumbers, computed wavenumbers were scaled with a scaling factor, and vibrational assignments were made by comparing experimental wavenumbers to scaled theoretical wavenumbers. Quantum chemical parameters have been determined and examined. Molecular electrostatic potential (MEP) surface plot analysis has been carried out at the same level of theory. Mulliken atomic charge study is also discussed in the present study.
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43

Rauwolf, Cordula, Achim Mehlhorn, and Jürgen Fabian. "Binding Energies of Organic Charge-Transfer Complexes Calculated by First-Principles Methods." Collection of Czechoslovak Chemical Communications 63, no. 8 (1998): 1223–44. http://dx.doi.org/10.1135/cccc19981223.

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Weak interactions between organic donor and acceptor molecules resulting in cofacially-stacked aggregates ("CT complexes") were studied by second-order many-body perturbation theory (MP2) and by gradient-corrected hybrid Hartree-Fock/density functional theory (B3LYP exchange-correlation functional). The complexes consist of tetrathiafulvalene (TTF) and related compounds and tetracyanoethylene (TCNE). Density functional theory (DFT) and MP2 molecular equilibrium geometries of the component structures are calculated by means of 6-31G*, 6-31G*(0.25), 6-31++G**, 6-31++G(3df,2p) and 6-311G** basis sets. Reliable molecular geometries are obtained for the donor and acceptor compounds considered. The geometries of the compounds were kept frozen in optimizing aggregate structures with respect to the intermolecular distance. The basis set superposition error (BSSE) was considered (counterpoise correction). According to the DFT and MP2 calculations laterally-displaced stacks are more stable than vertical stacks. The charge transfer from the donor to the acceptor is small in the ground state of the isolated complexes. The cp-corrected binding energies of TTF/TCNE amount to -1.7 and -6.3 kcal/mol at the DFT(B3LYP) and MP2(frozen) level of theory, respectively (6-31G* basis set). Larger binding energies were obtained by Hobza's 6-31G*(0.25) basis set. The larger MP2 binding energies suggest that the dispersion energy is underestimated or not considered by the B3LYP functional. The energy increases when S in TTF/TCNE is replaced by O or NH but decreases with substitution by Se. The charge-transferred complexes in the triplet state are favored in the vertical arrangement. Self-consistent-reaction-field (SCRF) calculations predicted a gain in binding energy with solvation for the ground-state complex. The ground-state charge transfer between the components is increased up to 0.8 e in polar solvents.
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44

ZHONG, AI-GUO, DINGBEN CHEN, MING LEI, and SHUBIN LIU. "UNDERSTANDING THE ROLE OF WATER IN PROMOTING E-ISOMER PRODUCTION AND PHOTOCHROMISM OF SOLID SCHIFF BASE: A DFT AND TD-DFT STUDY." Journal of Theoretical and Computational Chemistry 07, no. 05 (October 2008): 1071–84. http://dx.doi.org/10.1142/s0219633608004404.

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The formation mechanism and photochromic property of a novel solid state Schiff base compound (E-isomer, C 21 H 18 I 2 N 3 O 2) derived from 4-aminoantipyrine and 3,5-diiodosalicylaldehyde is investigated in this work using density functional theory at the B3LYP/6-31l++G** level with and without solvent water presence. Our computational results show that the conversion in the gas phase is unlikely to occur and the solvent water is involved in the reaction to decrease the barrier height. We considered one to three water molecule participations in the water-catalyzed mechanism to produce the E-isomer. Time-dependent density functional theory (B3LYP/6-311+G*) is employed to examine the photochromic property of the molecule. A large Stokes shift between absorption and emission has been attributed to the intramolecular H-transfer ( O – H ⋯ N to O ⋯ H – N ) following photoexcitation of the enol species, suggesting that the keto form of the photoproduct structure plays the key role, in agreement with the experimental finding of stereoselectivity. Conceptual DFT reactivity indices are employed to rationalize the findings from the present study.
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45

Jiao, Dongsheng, Hongyan Wang, Yanlan Zhang, and Yu Tang. "A DFT study of thymine and its tautomers." Canadian Journal of Chemistry 87, no. 2 (February 2009): 406–15. http://dx.doi.org/10.1139/v08-168.

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The structures and the relative energies of six possible tautomers of the thymine base have been studied by density functional theory (DFT) using the B3LYP and BP86 functionals. The keto-thymine (T1) is predicted to be the most stable thymine tautomer, which is consistent with the other theoretical results and experimental data. The corresponding thymine cations and anions are studied using the same level of theory with double-ζ plus polarization and diffuse functions (DZP++) basis sets. The ionization potentials (IPs), the electron affinities (EAs), and proton affinities (PAs) for different protonation sites in thymine base are obtained. T1 has the largest ionization potential and the lowest proton affinity among all the considered thymine tautomers.
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46

Toh, Pek Lan, Rosfayanti Rasmidi, Montha Meepripruk, Lee Sin Ang, Shukri Sulaiman, and Mohamed Ismail Mohamed-Ibrahim. "First Principles Density Functional Theory Investigation on the Structural, Energetic and Electronic Properties of 6–Bromo–4–Oxo–4H–Chromene–3–Carbaldehyde." Applied Mechanics and Materials 835 (May 2016): 308–14. http://dx.doi.org/10.4028/www.scientific.net/amm.835.308.

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In this paper, we report the first principles Density Functional Theory (DFT) calculation to study the structural, energetic, and electronics properties of the 6–Bromo–4–Oxo–4H–Chromene–3–Carbaldehyde, C10H5BrO3 molecular framework. Geometry optimization technique was carried out to find the local energy minimum of the title compound using four hybrid DFT functionals with the basis set of 6–311++G**. The optimized molecular structure of C10H5BrO3 cluster was then used to determine the HOMO–LUMO gaps, Molecular Electrostatic Potential (MEP), Mulliken atomic charges, and others. Using the four hybrid DFT techniques, the optimized geometries of C10H5BrO3 molecular cluster is close to that of measurement data. Our calculation results also show that the total energies obtained are close to each other with the four hybrid DFT procedures. The diagram of electrostatic potential surface show that the regions of negative electrostatic potential around the oxygen atoms, O1 and O2. Using the scheme of Mulliken Population Analysis (MPA), the distributions of atomic charges follow the same arguments for the B3LYP/6–311++G**, B3PW91/6–311++G**, M06/6–311++G**, and PBE1PBE/6–311++G** simulation approaches. For example, the atom of C5 has the highest positively charge, whereas the highest negatively charge was found in the C4 atom. For Br atom, the atomic charge values obtained are –0.158, –0.222, –0.277, and –0.224, respectively for the B3LYP/6–311++G**, B3PW91/6–311++G**, M06/6–311++G**, and PBE1PBE/6–311++G** computational methods.
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47

Thangarasu, S., V. Siva, A. Shameem, A. Murugan, S. Athimoolam, and S. Asath Bahadur. "Structural, Electronic, Molecular Orbital Analysis and Charge Distributions on Nitrate Salt of Guanidine through DFT and TD-DFT Methods." Asian Journal of Chemistry 33, no. 8 (2021): 1905–10. http://dx.doi.org/10.14233/ajchem.2021.23201.

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Guanidinium nitrate, a non-linear optical material has been systematically studied through quantum chemical (density functional theory and Hartree Fock) methods. Studies on Mulliken charge, Frontier molecular orbitals (FMOs) and hyperpolarizability analyses have been performed. The Mulliken population analyses were carried out for the optimized molecular geometry by HF and B3LYP methods with 6-311++G(d,p) levels. The molecular orbital parameters of guanidinium nitrate have been calculated by FMO analysis. Frontier molecular orbital (FMO) analysis indicates the electron delocalization on the guanidinium nitrate and also its low value of energy gap indicates electron transfer. Optical property has been investigated by time-dependent density functional theory (TD-DFT) calculation. The second-order hyperpolarizability value of the ion pairs is much greater than urea, which confirms the good NLO nature of guanidinium nitrate.
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48

Kumar, Sarvendra, Rajesh Kumar, Jayant Teotia, and M. K. Yadav. "Experimental and Theoretical (ab initio and DFT) Analysis of UV-Vis Spectra, Thermodynamic Functions and Non-linear Optical Properties of 2-Chloro-3,4-Dimethoxybenzaldehyde." JOURNAL OF ADVANCES IN PHYSICS 8, no. 2 (April 15, 2015): 2122–34. http://dx.doi.org/10.24297/jap.v8i2.1519.

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In the present work, UV- Visible spectra of 2-Chloro-3,4-Dimethoxybenzaldehyde (2,3,4-CDMB) compound have been carried out experimentally and theoretically. The ultraviolet absorption spectrum of title compound in three solvents (Acetone, Diethyl Ether, CCl4) of different polarity were examined in the range of 200–500 nm. The structure of the molecule was optimized and the structural characteristics were determined by HF and DFT (B3LYP) methods with 6-31+G(d,p) and 6-311++G(d,p) as basis sets. The excitation energy, wavelength corresponds to absorption maxima () and oscillator strength (f) are calculated by Time-Dependent Density Functional Theory (TD-DFT) using B3LYP/6-31+G(d,p) and B3LYP/6-311++G(d,p) as basis sets. The electric dipole moment (μ), polarizability (α) and the first hyperpolarizability (β ) have been computed to evaluate the non-linear optical (NLO) response of the investigated compound by HF and DFT (B3LYP) with already mentioned basis sets. Thermodynamic functions of the title compound at different temperatures were also calculated.
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49

Solaichamy, R., and J. Karpagam. "Molecular Structure, Vibrational Spectra and Docking Studies of Abacavir by Density Functional Theory." International Letters of Chemistry, Physics and Astronomy 72 (January 2017): 9–27. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.72.9.

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In this study, optimized geometry, spectroscopic (FT-IR, FT-Raman, UV) analysis, and electronic structure analysis of Abacavir were investigated by utilizing DFT/B3LYP with 6-31G(d,p) as a basis set. Complete vibrational assignments and correlation of the fundamental modes for the title compound were carried out. The calculated molecular geometry has been compared with available X-ray data of Abacavir. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The molecular stability and bond strength have been investigated by applying the Natural Bond Orbital (NBO) analysis. The computational molecular docking studies of title compound have been performed.
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50

Quang, Duong Tuan. "An investigation of the excitation and emission properties of fluorescence compounds using DFT and TD-DFT methods." Hue University Journal of Science: Natural Science 127, no. 1A (May 9, 2018): 43. http://dx.doi.org/10.26459/hueuni-jns.v127i1a.4777.

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<p class="03Abstract">The density functional theory and time-dependent density functional theory methods were used for investigation of the excitation and emission properties of some fluorophores. The calculations were based on the optimized geometries of ground states and excited states at the B3LYP functional and LanL2DZ basis set. The results clarified the nature of the optical properties of the compounds and agreed well with the experimental data. The approximate values of excitation energies and emission energies of compounds were also identified. The calculated excitation energies were about 0.01 to 0.56 eV higher than experimental values. Meanwhile, the emission energies were from 0.34 to 0.89 eV higher than experimental values. These large errors occurred when there were great variations between the optimized geometries of ground state and excited states. They could be due to the presence of components of solvent in real solution that stabilized the excited states, leading to reduce the excitation and emission energies in the experiments.</p>
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