Selected Torsion Angle Research Articles

Synthesis and Theoretical Characterization of 4-(p-tollyl)-5-(thiophen-2-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione Using Experimental and Quantum Chemical Calculations.

The aim of the study was to synthesize 4- (p-tollyl) -5- (thiophene-2-yl) -2,4-dihydro-3H-1,2,4-triazole-3-thione and detect its experimental and the quantum chemical properties. 4-(p-tollil)-5-(tiyofen-2-il)-2,4-dihidro-3H-1,2,4-triazol-3-tiyon was synthesized using by the nucleophilic sübstitüsyon reaction. The synthesized title compound has been characterized both experimentally and theoretically using quantum chemical calculations and spectral techniques. The molecular geometry, vibrational frequencies, and 1H and 13C NMR chemical shifts of the title compound in the ground state were calculated using the density functional method (B3LYP) with the 6–311G(d, p) basis set. It was seen that the calculated infrared and nuclear magnetic resonance values were compatible with the experimental values. To determine conformational flexibility, the molecular energy profile of 4- (p-tollyl) -5- (thiophene-2-yl) -2,4-dihydro-3H-1,2,4-triazole-3-thione was obtained by DFT calculations with respect to the selected torsion angle, which was varied from 180°to +180°in steps of 20°. In addition, the HOMO- LUMO energies of this conformational structure were calculated.

Bactericidal Activity and Structural Studies of the Steviol Derivative 17- Hydroxy-16-hydroxyiminobayeran-19-oic Acid

Background: According to the World Health Organization (WHO), the routine use of antibiotics has led to the increase of microbial resistance. Thus, the search for new compounds that present antimicrobial activity must be constant. This study reports the bactericidal activity assay of the steviol derivative 17-hydroxy-16-hydroxyiminobayeran-19-oic acid against various bacteria and structural studies by quantum chemistry and molecular dynamics. Methods: Bactericidal activity assays of the steviol derivative 17-hydroxy-16-hydroxyiminobayeran-19- oic acid against Salmonella typhimurium [ATCC 14028], Staphylococcus aureus [ATCC 6538], Bacillus cereus [ATCC 11778], Helicobacter pylori [ATCC 26695], Pseudomonas aeruginosa [ATCC 27853], Escherichia coli [ATCC 25922] and Bacillus subtilis [ATCC 23857] were performed, as well as structural studies by quantum chemistry and molecular dynamics. Results: The results show that the compound exhibits activity towards S. typhimurium, what makes it an interesting compound for future studies on the development of antibiotics against this bacteria. An intramolecular hydrogen bond does not seem to be maintained in solution, therefore, corresponding moieties should be prone to interactions with their surroundings. Conclusions: The results indicate that the title compound exhibits activity towards S. typhimurium, what sums up to similar results from other steviol derivatives and stevioside, thus reinforcing the potential of these compounds for future studies on the development of antibiotics against this bacteria. The potential energy surface for the selected torsion angles and molecular dynamics have revealed that an intramolecular hydrogen bond, though slightly energetically favorable, does not seem to be maintained in solution; therefore, corresponding moieties should be prone to interactions with their surroundings, an important feature in further studies involving inhibitor/drug design from this compound.

Experimental and theoretical investigation of N-(4-nitrobenzoyl)-S-(cyclohexyl)-dithiocarbamate, N-(4-nitrobenzoyl)-S-benzyldithiocarbamate

Two new dithiocarbamate molecules were synthesized and characterized by 1H NMR, 13C NMR, IR, and structural X-ray diffraction techniques. The molecular geometry, vibrational frequencies of the title compounds in the ground state have been calculated by using the Hartree-Fock (HF) and density functional theory (DFT) methods with 6–31G(d) basis set, also gauge-independent atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the title compound (I) have been calculated by the same methods and compared with the experimental data. The calculated results show that the optimized geometries can well reproduce the crystal structural parameters. A detailed vibrational spectral analysis has been carried out and assignments of observed fundamental bands have been proposed on basis of peak positions. The scaled theoretical frequencies showed very good agreement with experimental values. In addition, the computed 1H and 13C NMR chemical shift values are in line with experimental data. To determine conformational flexibility, the molecular energy profile of the title compounds were obtained in respect of the selected torsion angle, which were varied from −180° to +180° in steps of 10°. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP)analysis and thermodynamic properties were investigated by theoretical calculations.

Synthesis, crystal structure, spectroscopic characterization and theoretical calculations of (Z)-N-(naphthalen-2-yl)-1-(5-nitrothiophen-2-yl)methanimine

The newly synthesized Schiff base compound, (Z)-N-(naphthalen-2-yl)-1-(5-nitrothiophen-2-yl)methanimine, C15H10N2O2S, was characterized by IR, UV–Vis and X-ray diffraction technique. All of the theoretical calculations have been calculated at the LSDA, BVP86, B3LYP and B3PW91 levels of the density functional method (DFT) with the 6–311++G(d,p) basis set by Gaussian software. UV–Visible absorption spectra of the title compound dissolved in ethanol were recorded and computed using the time dependent density functional theory (TD-DFT). The harmonic vibrational frequencies of the title compound were calculated using the same methods. So as to determine most favorable conformation as theoretically, molecular energy profile of the title compound were obtained as a function of the selected torsion angle by steps of 10° in the range of −180° to +180° rotation around the bond. The conformational analysis is a relationship between the energy of the title compound and its geometry. It is demonstrated that comparison between the calculated and experimental results provide a very good agreement. The energetic behavior such as the total energy, atomic charges, dipole moment of the title compound in solvent media were examined using the same methods by applying the Onsager and the integral equation formalism polarizable continuum model (IEF-PCM).

Crystal structure and theoretical studies of derivative of imidazo-1,2,4-triazine

In this study, we present the result of X-ray structure analysis of methyl [8-(3-chlorophenyl)-4-oxo-2,3,4,6,7,8-heksahydroimidazo[2,1-c][1,2,4]triazin-3-yl]acetate (1). The molecule conformation is flat, with a chlorophenyl substituent and the ester moiety lying in the plain of the heterobicyclic scaffold. Its conformation is stabilized by an intramolecular NH…O hydrogen bond. Within the crystalline structure of 1, molecules associate with one another by weak CH…O, CH…Cl and CH…π bonds. The molecular and crystal structure of 1 was compared with the previously described structurally similar compound possessing the same bicyclic rigid core and similar chemical nature of the functional ester moiety. Very interesting differences in molecules geometry and association were observed. Non-covalent bonds within the crystals are additionally visualized by determination of Hirshfeld surfaces.Moreover, the quantum chemical calculation for 1 in the gas phase were carried out. The DFT calculation methods was used to optimize of molecule geometry and obtain molecular energy profiles with respect to selected torsion angles. The quantum chemical conformational analysis that was carried out for compound 1 in the gas phase suggests that in the solid state the molecules adopt the minimum energy conformation.

Towards solution and refinement of organic crystal structures by fitting to the atomic pair distribution function.

A method towards the solution and refinement of organic crystal structures by fitting to the atomic pair distribution function (PDF) is developed. Approximate lattice parameters and molecular geometry must be given as input. The molecule is generally treated as a rigid body. The positions and orientations of the molecules inside the unit cell are optimized starting from random values. The PDF is obtained from carefully measured X-ray powder diffraction data. The method resembles `real-space' methods for structure solution from powder data, but works with PDF data instead of the diffraction pattern itself. As such it may be used in situations where the organic compounds are not long-range-ordered, are poorly crystalline, or nanocrystalline. The procedure was applied to solve and refine the crystal structures of quinacridone (β phase), naphthalene and allopurinol. In the case of allopurinol it was even possible to successfully solve and refine the structure in P1 with four independent molecules. As an example of a flexible molecule, the crystal structure of paracetamol was refined using restraints for bond lengths, bond angles and selected torsion angles. In all cases, the resulting structures are in excellent agreement with structures from single-crystal data.

Spectroscopic and Quantum Chemical Studies of (Z)-N′-(3-(hidroksiimino)butan-2-ylidene)-4-metilbenzensulfonohidrazide Ligand

The structural and spectroscopic characterization of Schiff base ligand, (Z)-N′-(3-(hidroksiimino)butan-2-ylidene)-4metilbenzensulfonohidrazide (HL) are presented in this paper. The optimized geometry and vibrational frequencies of the ligand have been calculated by using DFT/B3LYP method with 6-311G(d,p) and 6-311G+(d,p) basis sets. The calculated wave numbers are used to assign vibrational bands obtained in IR spectroscopy and find out to the manifestations of hydrogen bonding in the νstr(N–H) and νstr(O–H) vibrations. The UV-Vis absorption peaks of the ligand predicted by the time-dependent DFT method matched quite well with experimentally observed UV-Vis bands. The molecular electrostatic potential and the energy profile with respect to rotations about the selected torsion angle τ(C5-S1-N3-N2) is also calculated.

A combined experimental and theoretical investigation of 2-Thienylboronic acid: Conformational search, molecular structure, NBO, NLO and FT-IR, FT-Raman, NMR and UV spectral analysis

The solid state Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectra of 2-Thienylboronic acid (2TBA), were recorded in the range of 4000–400cm−1 and 4000–100cm−1, respectively. DFT/B3LYP theory was used for the optimization of the ground state geometry and simulation of the infrared and Raman spectra of the title molecule. To determine lowest-energy molecular conformation of the studied molecule, the selected torsion angles were varied in steps of 10° and complete 3D molecular energy profile was calculated. Among the four possible conformers (Trans–Trans, Cis–Cis, Trans–Cis and Cis–Trans), the most stable conformer of 2TBA is the Trans–Cis form. The vibrational wavenumbers and their assignments were carried out theoretically using the Gaussian09 set of quantum chemistry codes and the normal modes were calculated using MOLVIB program. Experimental FT-IR and FT-Raman spectra of the title compound were compared with the spectral data obtained by DFT/B3LYP method. Dipole moment, polarizability, first static hyperpolarizability and molecular electrostatic potential surface (MEPs) map have been calculated to get a better perception of the properties of the title molecule. Natural bond orbital (NBO) analysis was performed to study the stability of the molecule arising from charge delocalization. UV–Vis spectrum of the title molecule was also recorded (500–200nm) in methanol and electronic properties such as frontier orbitals and energy gap were calculated by TD-DFT approach. The 1H nuclear magnetic resonance (NMR) chemical shifts of the studied molecule were recorded in DMSO-d6 and calculated by Gauge-Including Atomic Orbital (GIAO) method.

Molecular structure, vibrational and electronic properties of 4-Phenyl-3H-1,3-thiazol-2-ol using density functional theory and comparison of drug efficacy of keto and enol forms by QSAR analysis

4-Phenyl-3H-1,3-thiazol-2-ol can exist in two tautomeric forms – keto and enol. Comprehensive investigation of molecular geometry and electronic structure in ground as well as in the first excited state of 4-Phenyl-3H-1,3-thiazol-2-ol (enol) has been carried out. To determine lowest-energy molecular conformation of the title molecule, the selected torsion angles were varied in steps of 10° and molecular energy profile was calculated from −180° to +180°. Experimental FT-IR and FT-Raman spectra of title compound were compared with the spectral data obtained by DFT/B3LYP method. Dipole moment, polarizability, first static hyperpolarizability and molecular electrostatic potential surface map have been calculated to get a better insight of the properties of title molecule. Natural bond orbital (NBO) analysis has been done to study the stability of the molecule arising from charge delocalization. UV–Vis spectrum of the title compound was also recorded and electronic properties such as frontier orbitals and band gap energies were calculated by TD-DFT approach. To compare the drug efficacy of enolic and keto forms, QSAR properties of both forms have also been computed and discussed.

Determination of structural and vibrational spectroscopic features of neutral and anion forms of dinicotinic acid by using NMR, infrared and Raman experimental methods combined with DFT and HF

In this study; the experimental (NMR, infrared and Raman) and theoretical (HF and DFT) analysis of dinicotinic acid were presented. 1H and 13C NMR spectra were recorded in DMSO solution and chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The vibrational spectra of dinicotinic acid were recorded by FT-Raman and FT-IR spectra in the range of 4000–10cm−1 and 4000–400cm−1, respectively. To determine the most stable neutral conformer of molecule, the selected torsion angle was changed every 10° and molecular energy profile was calculated from 0° to 360°. The geometrical parameters and energies were obtained for all conformers form from density functional theory (DFT/B3LYP) and HF with 6-311++G(d,p) basis set calculations. However, the results of the most stable neutral and two anion forms (anion−1 and anion−2 forms) of dinicotinic acid are reported here. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational wavenumbers, calculated with scaled quantum mechanics (SQM) method and PQS program.

Synthesis, experimental, theoretical characterization and biological activities of 4-ethyl-5-(2-hydroxyphenyl)-2H-1,2,4-triazole-3(4H)-thione

This work presents the characterization of 4-ethyl-5-(2-hydroxyphenyl)-2H-1,2,4-triazole-3(4H)-thione (III) by quantum chemical calculations and spectral techniques. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of III in the ground state have been calculated using the density functional method (B3LYP) with the 6-31G(d) basis set. The calculated results show that the optimized geometry can well reproduce the crystal structure, and the theoretical vibrational frequencies and chemical shift values show good agreement with experimental values. To determine conformational flexibility, the molecular energy profile of the title compound was obtained by DFT calculations with respect to the selected torsion angle, which was varied from −180° to +180° in steps of 10°. The energetic behavior of III in solvent media was examined using the B3LYP method with the 6-31G(d) basis set by applying the Onsager and the polarizable continuum model (PCM). The predicted nonlinear optical properties of III are greater than ones of urea. In addition, DFT calculations of molecular electrostatic potentials and frontier molecular orbitals of III were carried out at the B3LYP/6-31G(d) level of theory. The title compound was screened for antibacterial, antifungal and antioxidant activities.

Ab initio and semi-empirical computational studies on 5-hydroxy-5,6-di-pyridin-2-yl-4,5-dihidro-2H-[1,2,4]triazine-3-thione

The title compound, 5-hydroxy-5,6-di-pyridin-2-yl-4,5-dihidro-2H-[1,2,4]triazine-3-thione (C13H11N5OS), was prepared and characterized by electronic spectroscopy and single-crystal X-ray diffraction (XRD). The compound crystallizes in the triclinic space group P-1 with a=8.5808(8)Å, b=8.7032(7)Å, c=10.0505(9)Å, α=84.194(7)°, β=75.181(7)° and γ=63.562(6)°. In addition to the molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the title compound in the ground state have been calculated using the Hartree–Fock (HF) and density functional theory (DFT) methods with 6-31G(d) basis sets. To determine conformational flexibility, the molecular energy profile of the title compound was obtained by semi-empirical (AM1) calculations with respect to the selected torsion angle, which was varied from −180° to +180° in steps of 10°. The energetic behavior of the title compound in solvent media was examined using the B3LYP method with the 6-31G(d) basis set by applying the Onsager and the Polarizable Continuum Model (PCM). By using TD-DFT method, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD-DFT method and the experimental one is determined. The predicted nonlinear optical properties of the title compound are much greater than ones of urea. In addition, the molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis and thermodynamic properties of the title compound were investigated using theoretical calculations.

Synthesis, molecular and crystal structure analysis of 2-bromo-4-chloro-6-{[4-(3-methyl-3-phenyl-cyclobutyl)-thiazol-2-yl]-hydrazonomethyl}-phenol by experimental methods and theoretical calculations

A novel hydrazone derivative 2-bromo-4-chloro-6-{[4-(3-methyl-3-phenyl-cyclobutyl)-thiazol-2-yl]-hydrazonomethyl}-phenol was synthesized and characterized by IR, UV–Vis spectroscopy and X-ray single crystal diffraction. The compound crystallizes in monoclinic space group P21/c with a=8.0862(3)Å, b=7.6168(1)Å, c=37.3168(12)Å and β=91.186(1)°. In addition, the molecular geometry and vibrational frequencies of the title compound in ground state have been calculated by using density functional theory (DFT) at B3LYP level with 6-31G and 6-31G(d,p) basis sets. The geometrical parameters of the title compound obtained from XRD studies are in good agreement with the calculated values. The analysis of IR spectrum supported by DFT calculations was particularly devoted to the manifestations of hydrogen bonding in the νstr(NH) and νstr(OH) vibrations. To determine the conformational flexibility for a selected torsion angle τ(C6C1C7N1) one-dimensional potential energy scan was performed using AM1 in the full range of 0–360° increasing of 10°. UV–Vis absorption spectrum of the compound has been compared to theoretical spectrum (vertical excitations) computed by time dependent density functional theory (TD-DFT). Besides frontier molecular orbitals and molecular electrostatic potential map analysis were investigated by theoretical calculations.

Experimental and quantum chemical computational study of (E)-1-[5-(3,4-dimethylphenyldiazenyl)-2-hydroxyphenyl]ethanone

In this work, the azo dye, (E)-1-[5-(3,4-dimethylphenyldiazenyl)-2-hydroxyphenyl]ethanone, has been synthesized and characterized by IR, and X-ray single-crystal determination. In the theoretical calculations, the stable structure geometry of the isolated molecule in gas phase was investigated under the framework of the density functional theory (B3LYP) with 6-31G (d, p). To designate lowest energy molecular conformation of the title molecule, the selected torsion angle was varied every 10° and the molecular energy profile was calculated from −180° to +180°. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis, and thermodynamic properties were described from the computational process. In addition to these calculations, we were investigated solvent effects on the nonlinear optical properties (NLO) of the title compound.

The spectroscopic (FT-Raman, FT-IR, UV and NMR), molecular electrostatic potential, polarizability and hyperpolarizability, NBO and HOMO–LUMO analysis of monomeric and dimeric structures of 4-chloro-3,5-dinitrobenzoic acid

Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of 4-chloro-3,5-dinitrobenzoic acid (CDNBA) were carried out by using density functional (DFT/B3LYP) method with 6-311++G(d,p) as basis set. To determine lowest-energy molecular conformation of the title molecule, the selected torsion angle is varied every 10° and molecular energy profile is calculated from 0° to 360°. The optimized geometrical parameters obtained by DFT calculations are in good conformity with single crystal XRD data. The FT-IR and FT-Raman spectra were measured in the condensed state. The fundamental vibrational wavenumbers as well as their intensities were calculated and a good agreement between observed and scaled calculated wavenumbers has been achieved. The electric dipole moment, polarizability and the first hyperpolarizability values of the CDNBA have been calculated at the same level of theory and basis set. The calculation results also show that the CDNBA molecule may has nonlinear optical (NLO) behavior with non-zero values. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. Ultraviolet–visible (UV) spectrum of the title molecule has also been calculated using CIS and TD-DFT methods. The calculated energy and oscillator strength almost exactly reproduce the experimental data. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. The thermodynamic properties of the studied compound at different temperatures were calculated.

N-(4-Nitrobenzoyl)-N′-(1,5-dimethyl-3-oxo-2-phenyl-1H-3(2H)-pyrazolyl)-thiourea hydrate: Synthesis, spectroscopic characterization, X-ray structure and DFT studies

The title molecule (C19H17N5O4S·H2O) was synthesized and characterized by IR-NMR spectroscopy, MS and single-crystal X-ray diffraction. The molecular geometry, vibrational frequencies and gauge-independent atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the compound in the ground state have been calculated by using the density functional theory (DFT) method with 6-31G(d) basis set, and compared with the experimental data. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. The calculated results show that the optimized geometries can well reproduce the crystal structural parameters, and the theoretical vibrational frequencies and 1H and 13C NMR chemical shift values show good agreement with experimental data. To determine conformational flexibility, the molecular energy profile of the title compound was obtained with respect to the selected torsion angle, which was varied from −180° to +180° in steps of 10°. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis and thermodynamic properties of the compound were investigated by theoretical calculations.

Molecular structure, spectroscopic (FT-IR, FT-Raman, 13C and 1H NMR, UV), polarizability and first-order hyperpolarizability, HOMO and LUMO analysis of 4′-methylbiphenyl-2-carbonitrile

In the present study, the molecular structure, vibrational and electronic transition, isotropic chemical shifts analysis of 4′-methylbiphenyl-2-carbonitrile were presented using experimental techniques (FT-IR, FT-Raman, NMR and UV) and quantum chemical calculations. FT-IR and FT-Raman spectra in solid state were observed in the region 4000–400 cm −1 and 3500–50 cm −1, respectively. The ultraviolet absorption spectrum of studied compound that dissolved in ethanol was examined in the range of 200–400 nm. The 1H and 13C NMR spectra were recorded in DMSO solution. To determine lowest-energy molecular conformation of the title molecule, the selected torsion angle is varied every 10° and molecular energy profile is calculated from 0° to 360°. The molecular structure and spectroscopic data of the molecule in the ground state were computed by density functional theory (DFT) using 6-31++G(d,p) basis set. The complete assignments of all vibrational modes were performed on the basis of the total energy distributions (TED) of the vibrational modes, computed with scaled quantum mechanics (SQM) method. 13C and 1H isotropic chemical shifts were computed using the gauge-invariant atomic orbital (GIAO) method. Moreover, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies, absorption wavelength were performed by time-dependent DFT approach. The dipole moment, linear polarizability and first hyperpolarizability values were also computed. The linear polarizabilities and first hyper polarizabilities of the studied molecule indicate that the compound is a good candidate of nonlinear optical materials. Comparison of the calculated frequencies, NMR chemical shifts, absorption wavelengths with the experimental values revealed that DFT method produces good results.

Synthesis, molecular conformation, vibrational and electronic transition, isometric chemical shift, polarizability and hyperpolarizability analysis of 3-(4-Methoxy-phenyl)-2-(4-nitro-phenyl)-acrylonitrile: A combined experimental and theoretical analysis

This work presents the synthesis and characterization of a novel compound, 3-(4-Methoxy-phenyl)-2-(4-nitro-phenyl)-acrylonitrile (abbreviated as 3-(4MP)-2-(4-NP)-AN, C 16H 12N 2O 3). The spectroscopic properties of the compound were examined by FT-IR, UV–vis and NMR ( 1H and 13C) techniques. FT-IR spectrum in solid state was observed in the region 4000–400 cm −1. The UV–vis absorption spectrum of the compound which dissolved in chloroform was recorded in the range of 200–800 nm. The 1H and 13C NMR spectra were recorded in CDCl 3 solution. To determine lowest-energy molecular conformation of the title molecule, the selected torsion angle is varied every 10° and molecular energy profile is calculated from 0° to 360°. The structural and spectroscopic data of the molecule in the ground state were calculated using density functional theory (DFT) employing B3LYP/6-31G(d,p) basis set. The dipole moment, linear polarizability and first hyperpolarizability values were also computed using the same basis set. A study on the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. The HOMO and LUMO analysis were used to elucidate information regarding charge transfer within the molecule. The vibrational wavenumbers were calculated and scaled values were compared with experimental FT-IR spectrum. The complete assignments were performed on the basis of the experimental results and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. Isotropic chemical shifts were calculated using the gauge-invariant atomic orbital (GIAO) method. Comparison of the calculated frequencies, NMR chemical shifts, absorption wavelengths with the experimental values revealed that DFT and TD-DFT method produce good results. The linear polarizabilities and first hyperpolarizabilities of the studied molecule indicate that the title compound can be used as a good nonlinear optical material. The thermodynamic properties of the studied compound at different temperatures were calculated, revealing the correlations between standard heat capacity, standard entropy, standard enthalpy changes and temperatures.

Experimental and Ab Initio Computational Studies on 4-(Benzhydryloxy)phthalonitrile

Molecular structure, atomic charges, dipole moments, total energies, and vibrational frequencies of 4-(benzhydryloxy)phthalonitrile in the ground state have been calculated using density functional theory (DFT) calculations and compared with the experimental data. Calculated frequencies are in good agreement with the corresponding experimental data. To determine conformational flexibility, the molecular energy profile of the title compound was obtained by semi-empirical (RAM1) calculations with respect to the selected torsion angle, which was varied from −180° to +180° in steps of 10°. In addition, frontier molecular orbitals (FMOs) analysis and thermodynamic properties of the title compound were investigated using theoretical calculations.

Structural and photophysical characterization, topological and conformational analysis of 2-o-tolyl-4-(3-N,N-dimethylaminophenyl-methylene)-oxazol-5-one

A novel oxazole-5-one derivative 2-o-tolyl-4-(3-N,N-dimethylaminophenylmethylene)-oxazol-5-one (TDPO) C19H18N2O2 is synthesized and characterized and the crystal structure is determined by X-ray crystallography. TDPO is monoclinic in the P21/c space group. The molecule adopts the Z configuration. To enlighten the flexibility of TDPO, the selected torsion angle is varied from −180° to 180° in each 10° separately, and the molecular energy profile is calculated and analyzed by density functional calculations. In addition, Bader’s QTAIM analysis is performed to investigate the intramolecular weak interactions.