Molecular Structure of Phenytoin: NMR, UV-Vis and Quantum Chemical Calculations (original) (raw)
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Crystal Growth & Design, 2019
A series of five derivatives of the anticonvulsant drug phenytoin was synthesized and their crystal structures were determined. The relationship between the molecular and crystal structure of the investigated compounds was rationalized in context of contribution of intermolecular interactions and supramolecular structural motifs. The conformational preferences were analyzed by comparing the rotational freedom of the phenyl groups in the investigated compounds with 5,5-diphenylhydantoins from the Cambridge Structural Database. With exception of compound 3 bearing the cyclopropyl group, the crystal packing of the investigated compounds contains centrosymmetric dimers linked by paired N-H•••O hydrogen bonds which further selforganize through pairs of C-H•••O interactions and a parallel interaction of two phenyl rings at a large offset into chains running along the c-axis. The principal feature of the crystal structure of compound 3 is formation of the chains by N-H•••O hydrogen bonds, C-H•••O and C-H•••π interactions. The coordination of phenytoin enables more rotational freedom for the phenyl groups. An emphasis was placed on docking of the investigated compounds into the voltage-gated ion channel in the open and closed state. The obtained results indicate that hydrogen bonding and hydrophobic interactions are dominant in stabilizing energetically-favored orientations of the investigated compounds bound to the protein.
In this paper, the spectral analysis of 1-phenyl-2-nitropropene is carried out using the FTIR, FT Raman, FT NMR and UV–Vis spectra of the compound with the help of quantum mechanical computations using abinitio and density functional theories. The FT-IR (4000–400 cm1) and FT-Raman (4000–100 cm1) spectra were recorded in solid phase, the 1H and 13C NMR spectra were recorded in CDCl3 solution phase and the UV–Vis (200–800 nm) spectrum was recorded in ethanol solution phase. The different conformers of the compound and their minimum energies are studied using B3LYP functional with 6-311+G(d,p) basis set and two stable conformers with lowest energy were identified and the same was used for further computations. The computed wavenumbers from different methods are scaled so as to agree with the experimental values and the scaling factors are reported. All the modes of vibrations are assigned and the structure the molecule is analyzed in terms of parameters like bond length, bond angle and dihedral angle predicted by both B3LYP and B3PW91 methods with 6-311+G(d,p) and 6-311++G(d,p) basis sets. The values of dipole moment (l), polarizability (a) and hyperpolarizability (b) of the molecule are reported, using which the non-linear property of the molecule is discussed. The HOMO–LUMO mappings are reported which reveals the different charge transfer possibilities within the molecule. The isotropic chemical shifts predicted for 1H and 13C atoms using gauge invariant atomic orbital (GIAO) theory show good agreement with experimental shifts. NBO analysis is carried out to picture the charge transfer
In this study, 4-Methoxy-N-(3-phenylallylidene) aniline has been synthesized and characterized by FTIR and NMR spectroscopic techniques. The optimized geometrical structure, vibrational frequencies and NMR shifts of title molecule were obtained by using ab initio HF and density functional method (B3LYP) with 6-31G* basis set. The experimental and calculated geometrical parameters were compared with each other. The calculated infrared (IR) and NMR data were compared with experimental values using HF and B3LYP/6-31G* level of theory. It was found to be a good correlation between experimental and calculated data. In addition, HOMO and LUMO analysis of title molecule were calculated using corresponding methods with 6-31G* basis set. The calculated HOMO-LUMO energies were used to calculate some properties of title molecule.
Monatshefte für Chemie - Chemical Monthly, 2011
A series of 5-substituted 5-phenylhydantoins was synthesized and their UV absorption spectra were recorded in the region 200-400 nm in selected solvents of different polarity. The effects of solvent dipolarity/polarizability and solvent-solute hydrogen-bonding interactions were analyzed by means of the linear solvation energy relationship concept proposed by Kamlet and Taft. The lipophilicities of the investigated hydantoins were estimated by calculation of their log P values. The quantitative relationship between the ratio of the contributions of specific solvent interactions and the corresponding lipophilicity parameter is discussed. The correlation equations were combined with the corresponding ED 50 values and different physicochemical parameters to generate new equations that demonstrate the reasonable relationships between solute-solvent interactions and the structureactivity parameters. In order to determine a spectroscopic assignment of the absorption bands in different solvents, quantum chemical calculations were done.
In this work, experimental and theoretical UV, NMR and vibrational spectra of 2-thiohydantoin (2-TH) were studied. We have used a combined FT-IR and FT-Raman spectroscopy along with Density Functional Theory (DFT) to study the effect of hydrogen bonding on molecular structure. Comparison between the gas phase and the solid phase data were also carried out. Our results support the hydrogen bonding pattern proposed by the reported crystal structure and provide valuable information on the structural relationship between the investigated polymorphs. The ultra violet absorption spectra of the compound dissolved in methanol were examined in the range 210-330 nm. The solid state 13 C NMR spectra were recorded. Isotropic chemical shifts were calculated using the gauge-invariant atomic orbital (GIAO) method. Comparison of the calculated NMR chemical shifts and absorption wavelengths with the experimental values revealed that DFT method produces good results.
Materials Today: Proceedings, 2016
The Fourier Transform Infrared (FTIR) spectrum of 2-azido-1-phenylethanone (APE) has been recorded in the range 4000-400 cm-1 respectively. The optimized geometry of the molecule has been computed by evaluating the torsional potential energy as a function of angle of rotation about the interlinking bonds of APE using quantum chemical calculations. These calculations were carried out using density functional theory (DFT) employing B3LYP functional with 6-311++G(d,p) basis set. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The values of dipole moment, polarizability and hyperpolarizability were computed to determine the NLO behaviour of the molecule under study. The HOMO and LUMO energies were also evaluated for this molecule to demonstrate the chemical stability.
Journal of Molecular Structure, 2014
In this study, the molecular structure and vibrational and electronic transition spectra and 1 H and 13 C NMR chemical shift values (gas phase and in chloroform solvent), HOMO-LUMO analysis, molecular electrostatic potential (MEP), thermodynamic properties and Mulliken atomic charges of (E)-3-[4-(Pentyloxy)phenyl]-1-phenylprop-2-en-1-one molecule, C 20 H 22 O 2 , which has many biological activities have been calculated using the DFT/B3LYP method with 6-311++G(d,p) basis set in the ground state. The obtained results indicate a good harmony among the calculated and the experimental FT-IR, Raman, UV-vis. (in methanol solvent) and 1 H and 13 C NMR (in chloroform-d solvent) spectra of the mentioned compound.
Chemical Data Collections, 2020
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Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2015
In this paper, the spectral analysis of 3-methyl-1-phenylpyrazole is carried out using the FT-IR, FT Raman, FT NMR and UV-Vis spectra with the help of quantum mechanical computations using HF and density functional theories. The different conformers of the compound and their minimum energies are studied using B3LYP functional with 6-311+G (d,p) basis set and the most stable conformer with minimum energy was identified and the same conformer was used for further computations. The computed wave numbers from different methods are scaled so as to agree with the experimental values and the scaling factors are reported. All the modes of vibrations are assigned and the structure the molecule is analyzed in terms of parameters like bond length, bond angle and dihedral angle predicted by both HF and B3LYP methods with 6-311+G (d,p) and 6-311++G (d,p) basis sets. The values of dipole moment (μ), polarizability (α) and hyperpolarizability (β) of the molecule are reported, using which the non-l...