A DFT Analysis of the Molecular Structures and Vibrational Spectra of Diphenylsulfone and 4,4'-Sulfonyldianiline (Dapsone)

2011 ◽  
Vol 66 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Wolfgang Förner ◽  
Hassan M. Badawi
Keyword(s):  
Vibrational Spectra ◽  
Density Functional ◽  
Parent Compound ◽  
Harmonic Approximation ◽  
Molecular Structures ◽  
Spectral Lines ◽  
Basis Set ◽  
Minor Role ◽  
Parent Molecule ◽  
Chemical Difference

We have performed density functional calculations with the B3LYP functional and a 6-311G** basis set to obtain the vibrational spectra in harmonic approximation of the anti-leprosy drug Dapsone and the parent compound diphenylsulfone. Although the chemical difference between the two molecules is not that pronounced (Dapsone has amino groups in the para positions in the phenyl rings), Dapsone is an active drug, while to our knowledge diphenylsulfone shows no medical activity. We compared the theoretical results to experimental vibrational spectra found in the literature. With the help of the program GAUSSVIEW we were able to assign the experimentally found spectral lines to specific atomic motions. The remarkable difference between the two molecules, regarding their structural behavior, is that the drug Dapsone has a more flexible structure of the phenyl ring than the parent molecule has. This might contribute to a greater ability of the drug to fit into receptor sites in a cell membrane although one has to be well aware that this plays most propably only a minor role in the drug activity of Dapsone

Experimental FTIR and theoretical investigation of the molecular structure and vibrational spectra of acetanilide using DFT and dispersion correction to DFT

2019 ◽  
Vol 18 (02) ◽  
pp. 1950009 ◽  
Author(s):  
Yunusa Umar ◽  
Nedal Abu-Thabit ◽  
Paul Jerabek ◽  
Ponnadurai Ramasami
Keyword(s):  
Vibrational Spectra ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Density Functional Theory Method ◽  
Molecular Structures ◽  
Basis Set ◽  
Potential Energy Distribution ◽  
Energy Decomposition Analysis ◽  
Dispersion Correction ◽  
Vibrational Assignments

The FTIR spectrum of acetanilide (ACN) is recorded and analyzed. The optimized molecular structures, harmonic vibrational wavenumbers and corresponding vibrational assignments of the ACN are computationally examined by using the B3LYP density functional theory method together with the standard 6-311[Formula: see text]G([Formula: see text],[Formula: see text]) basis set. From the calculations, the ACN is predicted to exist predominantly in trans configuration with the relative energy, rotational barrier, and population of 2.8[Formula: see text]kcal/mol, 14.8[Formula: see text]kcal/mol, and 99.5%, respectively. The optimized structure shows that the amide group (CO–NH) of trans-ACN adopts a planar peptide-like conformation. The effect of the incorporation of dispersion correction to the B3LYP on the calculated equilibrium structure and vibrational spectra of ACN is investigated. The highest occupied and the lowest unoccupied molecular orbitals, IR intensities and molecular electrostatic potential results are reported. In addition, reliable vibrational assignments have been made on the basis of Potential Energy Distribution (PED) using VEDA4 program. Simulated IR spectrum are compared with the experimental FTIR and FT-Raman spectra. Energy decomposition analysis (EDA) revealed that Pauli repulsion is responsible for the increased stability of the trans over the cis isomer.

A DFT ANALYSIS OF THE MOLECULAR STRUCTURES AND VIBRATIONAL SPECTRA OF 4,4′-SULFONYLDIPHENOL

2012 ◽  
Vol 11 (04) ◽  
pp. 821-832 ◽  
Author(s):  
WOLFGANG FÖRNER ◽  
HASSAN M. BADAWI
Keyword(s):  
Relative Intensity ◽  
Vibrational Spectra ◽  
Density Functional ◽  
Normal Modes ◽  
Molecular Structures ◽  
Basis Set ◽  
Substituted Anilines ◽  
Bisphenol S ◽  
Sulfa Drug ◽  
Complete Assignment

We have studied the structural properties and vibrational spectra of Bisphenol S (4,4′-sulfonyldi-phenol) with the help of Density Functional Calculations using a 6-311G∗∗ basis set. In addition we recorded experimental spectra in our laboratory. With the help of the GaussView program we could provide a complete assignment of the vibrational lines to the calculated normal modes of the molecule. The calculated and experimental vibrational spectra agree rather well with each other and we found the properties of Bisphenol S to be rather similar to the sulfa drug dapsone studied earlier. Interestingly, the electron donating power of an OH aubstituent at a phenyl ring seems to be less effective than that of an NH2 (in dapsone) substituent, because in Bisphenol S the relative intensity of the ring breathing line in the Raman spectrum appears to be much larger than in dapsone. We reach this conclusion about the electron donating powers of susbtituents, because in an early study on chlorine substituted anilines we have found that the larger the electron density in the ring becomes, the more the relative intensity of that line diminishes.

scholarly journals Assessing the Performance of Density Functional Theory Methods on the Prediction of Low-Frequency Vibrational Spectra

2020 ◽  
Author(s):  
Peter Banks ◽  
Zihui Song ◽  
Michael Ruggiero
Keyword(s):  
Density Functional Theory ◽  
Vibrational Spectra ◽  
Density Functional ◽  
Low Frequency ◽  
Intermolecular Forces ◽  
State Density ◽  
Basis Set ◽  
Valuable Insight ◽  
Great Success ◽  
Functional Theory

The low-frequency (terahertz) dynamics of condensed phase materials provide valuable insight into numerous bulk phenomena. However, the assignment and interpretation of experimental results requires computational methods due to the complex mode-types that depend on weak intermolecular forces. Solid-state density functional theory has been used in this regard with great success, yet the selection of specific computational parameters, namely the chosen basis set and density functional, has a profound influence on the accuracy of predicted spectra. In this work, the role of these two parameters is investigated in a series of organic molecular crystals, in order to assess the ability of various methods to reproduce intermolecular forces, and subsequently experimental terahertz spectra. Specifically, naphthalene, oxalic acid, and thymine were chosen based on the varied intermolecular interactions present in each material. The results highlight that unconstrained geometry optimizations can be used as an initial proxy for the accuracy of interatomic forces, with errors in the calculated geometries indicative of subsequent errors in the calculated low-frequency vibrational spectra, providing a powerful metric for the validation of theoretical results. Finally, the origins of the observed shortcomings are analyzed, providing a basic framework for further studies on related materials.

Charge transfer complexes between 2-, 3- and 4-aminopyridines and some π-acceptors in the gas phase and in chloroform: DFT calculations

2016 ◽  
Vol 15 (04) ◽  
pp. 1650029 ◽  
Author(s):  
Nuha Ahmed Wazzan
Keyword(s):  
Charge Transfer ◽  
Dft Calculations ◽  
Gas Phase ◽  
Density Functional ◽  
Molecular Structures ◽  
Basis Set ◽  
Charge Transfer Complexes ◽  
Good Correspondence ◽  
Electronic Distribution ◽  
Picryl Chloride

This work reports density functional theory (DFT) calculations on the molecular structures, electronic distribution, and UV-Vis and IR spectroscopy analysis of charge transfer complexes between aminopyridines (APYs), namely 2-APY, 3-APY and 4-APY, as electron-donors and some [Formula: see text]-electron-acceptors, namely chloranil (CHL), tetracyanoethylene (TCNE) and picryl chloride (PC), formed in the gas phase at the B3LYP/6-31[Formula: see text]G(d,p) method/basis set, and in chloroform at the same method/basis set using PCM as solvation model. Good correspondence was generally obtained between the calculated parameters and the experimental ones.

scholarly journals Intermolecular Interactions in Molecular Organic Crystals upon Relaxation of Lattice Parameters

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 665 ◽  
Author(s):  
Matthias Stein ◽  
Madalen Heimsaat
Keyword(s):  
Structure Prediction ◽  
Density Functional ◽  
Unit Cell ◽  
Lattice Parameters ◽  
Molecular Structures ◽  
Basis Set ◽  
Experimental Unit ◽  
Organic Crystals ◽  
Cell Parameters ◽  
Lattice Energies

Crystal structure prediction is based on the assumption that the most thermodynamically stable structure will crystallize first. The existence of other structures such as polymorphs or from counterenantiomers requires an accurate calculation of the electronic energy. Using atom-centered Gaussian basis functions in periodic Density Functional Theory (DFT) calculations in Turbomole, the performance of two dispersion-corrected functionals, PBE-D3 and B97-D, is assessed for molecular organic crystals of the X23 benchmark set. B97-D shows a MAE (mean absolute error) of 4 kJ/mol, compared to 9 kJ/mol for PBE-D3. A strategy for the convergence of lattice energies towards the basis set limit is outlined. A simultaneous minimization of molecular structures and lattice parameters shows that both methods are able to reproduce experimental unit cell parameters to within 4–5%. Calculated lattice energies, however, deviate slightly more from the experiment, i.e., by 0.4 kJ/mol after unit cell optimization for PBE-D3 and 0.5 kJ/mol for B97-D. The accuracy of the calculated lattice energies compared to the experimental values demonstrates the ability of current DFT methods to assist in the quest for possible polymorphs and enantioselective crystallization processes.

Density functional theory studies of conformational stabilities and rotational barriers of 2- and 3-thiophenecarboxaldehydes

2016 ◽  
Vol 57 (8) ◽  
pp. 1640
Author(s):  
Y. Umar ◽  
J. Tijani ◽  
S. Abdalla
Keyword(s):  
Density Functional ◽  
Dipole Moments ◽  
Structural Parameters ◽  
Conformational Stability ◽  
Energy Difference ◽  
Polarizable Continuum Model ◽  
Molecular Structures ◽  
Basis Set ◽  
Potential Energy Distribution ◽  
Vibrational Wavenumbers

The molecular structures, conformational stabilities, and infrared vibrational wavenumbers of 2-thiophenecarboxaldehyde and 3-thiophenecarboxaldehyde are computed using Becke-3—Lee—Yang—Parr (B3LYP) with the 6-311++G** basis set. From the computations, cis-2-thiophenecarboxaldehyde is found to be more stable than the transfer conformer with an energy difference of 1.22 kcal/mol, while trans-3-thiophenecarboxaldehyde is found to be more stable than the cis conformer by 0.89 kcal/mol. The computed dipole moments, structural parameters, relative stabilities of the conformers and infrared vibrational wavenumbers of the two molecules coherently support the experimental data in the literature. The normal vibrational wavenumbers are characterized in terms of the potential energy distribution using the VEDA4 program. The effect of solvents on the conformational stability of the molecules in nine different solvents is investigated using the polarizable continuum model.

Sign in / Sign up

Export Citation Format

Share Document