scholarly journals Theoretical Calculations for the Acidity of Cyanopolyynes HC2n+1N (n = 0–5) in Gas and Aqueous Phases Using Ab initio Methods

2019 ◽  
Vol 7 (1) ◽  
pp. 27
Author(s):  
Hassan H. Abdallah
Keyword(s):  
Gas Phase ◽  
Aqueous Phase ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Dust Cloud ◽  
Basis Set ◽  
Ab Initio Methods ◽  
Functional Theory ◽  
Moller Plesset ◽  
Cold Dust

Cyanopolyynes have been found in the interstellar medium, cold dust cloud Taurus Molecular Cloud-1, and the Titan’s atmosphere. Theoretical calculations are carried out to predict gas and aqueous phase acidities of a series of cyanopolyynes acids. Two levels of theory were used in this study, with the combination of density functional theory, and Møller–Plesset perturbation (MP2) theory, MP2 methods with two types of basis set, namely, Pople’s 6–311++g (d, p) basis set and Dunning’s aug-cc-pVTZ basis set. The calculations of these molecules reveal that pKa values varying from 12.25 to 17.25 and indicate that the acidity of these molecules in aqueous phase increases whereas the acidity in gas phase decreases with an increasing chain length of these acids.

scholarly journals Theoretical Investigation of the Quasi-ring C–H…π Interactions

2021 ◽  
Vol 18 (2) ◽  
pp. 119-128
Author(s):  
Sin Ang Lee ◽  
◽  
Zaidi Ab Ghani ◽  
Mohd Hafiz Yaakob ◽  
Mohamed Ismail Mohamed-Ibrahim ◽  
...  
Keyword(s):  
Density Functional ◽  
Theoretical Calculations ◽  
Basis Set ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Crystalline Materials ◽  
Π Interactions ◽  
Linear Chains ◽  
Moller Plesset ◽  
The Stability

The quasi-ring C–H…π interactions have been reported to be responsible for the stability of crystalline materials. The statistical analysis, together with electronic structure calculations in the framework of density functional theory and Moller-Plesset have also provided positive data on the aforementioned interactions. However, improvements can be had in the theoretical calculations, where the basis set convergence is not explored. This is crucial as the interactions are of weak type, reported to be around 4 – 5 kcal mol–1. In this investigation, the idea is to combine the geometry, potential energy surface, and bonding analysis to provide different insights into the interactions. Our results show that the original configurations of the crystals, even with the substitutions of linear chains, are more favorable than the rotated ones. Further calculations are needed to verify the involvements of the π orbitals of the N, C, Cl, S and the d-orbital of Cu, and the s-orbital of hydrogen atoms.

Donor Functionalized Perylene and Different π-Spacers Based Sensitizers for DSSC Applications - A Theoretical Approach

2021 ◽  
Author(s):  
D. Nicksonsebastin ◽  
P. Pounraj ◽  
Prasath M
Keyword(s):  
Density Functional Theory ◽  
Solar Cell ◽  
Gas Phase ◽  
Density Functional ◽  
Basis Set ◽  
Dye Sensitized Solar Cell ◽  
Functional Theory ◽  
Dye Sensitized ◽  
Td Dft ◽  
Organic Sensitizers

Abstract Perylene based novel organic sensitizers for the Dye sensitized solar cell applications are investigated by using Density functional theory (DFT) and time dependant density functional theory (TD-DFT).The designed sensitizers have perylene and dimethylamine (DM) and N-N-dimethylaniline(DMA) functionalized perylene for the dssc applications.π-spacers are thiophene andcyanovinyl groups and cyanoacrylic acid is chosen as the acceptor for the designed sensitizers. The studied sensitizers were fully optimized by density functional theory at B3LYP/6-311G basis set on gas phase and DMF phase. The electronic absorption of the sensitizers is analyzed by TD-DFT at B3LYP/6-311G basis set in both gas and DMF phase.

SOLVENT EFFECTS ON THE ELECTRONIC STRUCTURE AND NON-LINEAR OPTICAL PROPERTIES OF PYRENE AND SOME OF ITS DERIVATIVES BASED ON DENSITY FUNCTIONAL THEORY

2021 ◽  
Vol 4 (4) ◽  
pp. 236-251
Author(s):  
A. S. Gidado ◽  
L. S. Taura ◽  
A. Musa
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Energy Gap ◽  
Chemical Reactivity ◽  
Basis Set ◽  
Lumo Energy ◽  
Functional Theory ◽  
Organic Optoelectronic ◽  
Homo Lumo

Pyrene (C16H10) is an organic semiconductor which has wide applications in the field of organic electronics suitable for the development of organic light emitting diodes (OLED) and organic photovoltaic cells (OPV). In this work, Density Functional Theory (DFT) using Becke’s three and Lee Yang Parr (B3LYP) functional with basis set 6-311++G(d, p) implemented in Gaussian 03 package was  used to compute total energy, bond parameters, HOMO-LUMO energy gap, electron affinity, ionization potential, chemical reactivity descriptors, dipole moment, isotropic polarizability (α), anisotropy of polarizability ( Δ∝) total first order hyper-polarizability () and second order hyperpolarizability (). The molecules used are pyrene, 1-chloropyrene and 4-chloropyrene  in gas phase and in five different solvents: benzene, chloroform, acetone, DMSO and water. The results obtained show that solvents and chlorination actually influenced the properties of the molecules. The isolated pyrene in acetone has the largest value of HOMO-LUMO energy gap of and is a bit closer to a previously reported experimental value of  and hence is the most stable. Thus, the pyrene molecule has more kinetic stability and can be described as low reactive molecule. The calculated dipole moments are in the order of 4-chloropyrene (1.7645 D) < 1-chloropyrene (1.9663 D) in gas phase. The anisotropy of polarizability ( for pyrene and its derivatives were found to increase with increasing polarity of the solvents.  In a nutshell, the molecules will be promising for organic optoelectronic devices based on their computed properties as reported by this work.

scholarly journals 1,3-Di(hetero)aryl-7-substituted Pyrenes—An Undiscovered Area of Important Pyrene Derivatives

Proceedings ◽  
2019 ◽  
Vol 41 (1) ◽  
pp. 28
Author(s):  
Dawid Zych
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Basis Set ◽  
Functional Theory ◽  
Td Dft ◽  
Pyrene Derivatives ◽  
Osmium Complexes ◽  
The Subject ◽  
Theoretical Considerations

In this work, the necessity of synthesis of 1,3-di(hetero)aryl-7-substituted pyrenes is presented based on the results of theoretical calculations by using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) by using Gaussian 09 program with B3LYP exchange-correlation functional and 6-31G** basis set. What is more, the synthetic routes with feasible reagents and conditions are presented. The subject of theoretical considerations are two pyrene derivatives which contain at position 1 and 3 pyrazolyl substituents and at position 7 amine (1) or boron (2) derivative. The theoretical calculations were also performed for the osmium complexes with mentioned ligands (3 and 4). The influence of electron-donating/accepting character of the substituent at position 7 of pyrene on the properties of molecules has been established.

Homolytic bond-dissociation enthalpies of tin bonds and tin–ligand bond strengths — A computational study

2009 ◽  
Vol 87 (7) ◽  
pp. 974-983 ◽  
Author(s):  
Sarah R. Whittleton ◽  
Russell J. Boyd ◽  
T. Bruce Grindley
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Basis Set ◽  
Functional Theory ◽  
Bond Dissociation ◽  
Donor Acceptor ◽  
Bond Strengths ◽  
Moller Plesset ◽  
Effective Core Potentials ◽  
Ligand Bond

Density functional theory and second-order Møller–Plesset perturbation theory with effective core potentials have been used to calculate homolytic bond-dissociation enthalpies, D(Sn–X), of organotin compounds, and their performance has been assessed by comparison with available experimental bond enthalpies. The SDB-aug-cc-pVTZ basis set with its effective core potential was used to calculate the D(Sn–X) of a series of trimethyltin(IV) species, Me3Sn–X, where X = H, CH3, CH2CH3, NH2, OH, Cl, and F. This is the most comprehensive report to date of homolytic Sn–X bond-dissociation enthalpies (BDEs). Effective core potentials are then used to calculate thermodynamic parameters including donor–acceptor bond enthalpies, [Formula: see text], for a series of tin-ligand complexes, L2SnX4 (X = Br or Cl, L = py, dmf, or dmtf), which are compared with previous experimental and nonrelativistic computational results. Based on computational efficiency and accuracy, it is concluded that effective core potentials are appropriate computational methods to examine bonding in organotin systems.

scholarly journals Protonated heterocyclic derivatives of cyclopropane and cyclopropanone: classical species, alternate sites, and ring fragmentation

2015 ◽  
Vol 93 (7) ◽  
pp. 708-714 ◽  
Author(s):  
Margarida S. Miranda ◽  
Darío J.R. Duarte ◽  
Joaquim C.G. Esteves da Silva ◽  
Joel F. Liebman
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Computational Study ◽  
Basis Set ◽  
Proton Affinities ◽  
Functional Theory ◽  
Heterocyclic Derivatives ◽  
Gas Phase Basicities ◽  
Derivatives Of

A computational study has been performed for protonated oxygen- or nitrogen-containing heterocyclic derivatives of cyclopropane and cyclopropanone. We have searched for the most stable conformations of the protonated species using density functional theory with the B3LYP functional and the 6-31G(2df,p) basis set. More accurate enthalpy values were obtained from G4 calculations. Proton affinities and gas-phase basicities were accordingly derived.

Experimental and Theoretical Studies of Rotational Barriers in Aceto-, N-Methylaceto- and N-Phenylacetohydroxamic Acid

2001 ◽  
Vol 66 (1) ◽  
pp. 99-108 ◽  
Author(s):  
David A. Brown ◽  
Laurence P. Cuffe ◽  
Geraldine M. Fitzpatrick ◽  
Noel J. Fitzpatrick ◽  
William K. Glass ◽  
...  
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Zero Point ◽  
Density Functional Theory Calculations ◽  
Point Energy ◽  
Hartree Fock ◽  
Barrier Heights ◽  
Rotational Barriers ◽  
Moller Plesset

Experimental and theoretical calculations for the E and Z forms of aceto-, N-methylaceto- and N-phenylacetohydroxamic acid are reported. The experimental method was NMR spectroscopy, while the computational methods included Hartree-Fock, Møller-Plesset and density functional theory calculations, with and without solvation, using either the Onsager or Tomasi's PCM method. In all calculations zero point energy corrections were included. The computed results when compared with the experimental ones show that, irrespective of the method used, the differences in the rotational barriers, ∆(E-TS) and ∆(Z-TS), are slight and below the 3 kcal mol-1 limit of the theoretical methods. In general the results using the PCM method were worse than the ones obtained from gas phase calculations or using the Onsager method, even though the PCM method is computationally most expensive. The calculations show, using either the Hartree-Fock or the B3LYP approach, that considering solvation using the Onsager method improves agreement with the experiment results. The calculated barrier heights, excluding the PCM method, agree broadly with the experimental results. Thus using the Onsager approach or gas phase calculations adequate results for barrier heights, but not for relative differences, were obtained.

Resonance Raman and absorption infrared with density functional theory studies of Fe(III)/Fe(II) and Ni(II) complexes of modified 21-oxaporphyrins

2013 ◽  
Vol 17 (04) ◽  
pp. 289-308 ◽  
Author(s):  
Mateusz Fościak ◽  
Edyta Proniewicz ◽  
Krzysztof Zborowski ◽  
Younkyoo Kim ◽  
Leonard M. Proniewicz
Keyword(s):  
Density Functional ◽  
Theoretical Calculations ◽  
Resonance Raman ◽  
Vibrational Analysis ◽  
Basis Set ◽  
Functional Theory ◽  
B3lyp Level ◽  
Ft Ir ◽  
Optimized Geometries ◽  
Good Agreement

This work presents a complete vibrational analysis of iron [ Fe (II) and Fe (III)] and nickel [ Ni (II)] complexes with 5,10,15,20-tetraphenyl-21-oxaporphyrin [OTPPH] and 5,20-bis(p-tolyl)-10,15-diphenyl-21-oxaporphyrin [ODTDPPH]. In these porphyrins, a furan ring replaces one of the pyrrole rings. The six-coordinate (OTPP) FeIIICl2 and (ODTDPP) FeIIICl2 as well as the five-coordinate (OTPP) FeIICl and (OTPP) NiIICl complexes were investigated using experimental and theoretical methods. The experimental part of this work involved Fourier-transform absorption infrared (FT-IR), resonance Raman (RR), and electron absorption (UV-vis) measurements for all of the investigated complexes. In the theoretical section, optimized geometries and vibrational frequencies for model compounds are provided. The theoretical calculations were performed at the B3LYP level with the LANL2DZ basis set. Good agreement was achieved between the experimental and theoretical vibrational spectra. In addition, charge distributions (GAPT) and geometrical aromaticity indices (Bird's I5 and HOMA) were calculated and discussed.

A Combined Experimental and Theoretical Study on the Reaction Mechanism and Molecular Structure of 4-(Diphenylamino)-3-iodo-2(5H)-furanone

2017 ◽  
Vol 70 (7) ◽  
pp. 837
Author(s):  
Xiumei Song ◽  
Fuling Xue ◽  
Zongcai Feng ◽  
Yun Wang ◽  
Zhaoyang Wang ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Density Functional ◽  
Reaction Pathway ◽  
Theoretical Calculations ◽  
Calculation Model ◽  
Basis Set ◽  
Functional Theory ◽  
Evaporation Technique ◽  
Molecular Structure Analysis ◽  
Semi Empirical

The simultaneous α-iodination and Nβ-arylation mechanism of 5-alkyloxy-4-phenylamino-2(5H)-furanone by (diacetoxyiodo)benzene was investigated by means of density functional theory (DFT) with B3LYP/6-31G*//LANL2DZ, selecting 4-(diphenylamino)-5-methyloxy-3-iodo-2(5H)-furanone as the calculation model. In addition, the effect of solvent on the reaction pathway was investigated using the Polarisable Continuum Model (PCM). Good agreement was found between the computational and the experimental results. Furthermore, single crystals of 4-(diphenylamino)-5-ethoxy-3-iodo-2(5H)-furanone were grown by slow evaporation technique. The molecular structure analysis was performed by single crystal X-ray analysis and theoretical calculations using a semi-empirical quantum chemical method and DFT/B3LYP methods with a LANL2DZ as basis set.

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.

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