Experimental and theoretical studies on o-, m- and p-chlorobenzylideneaminoantipyrines

Theoretical investigation on the geometric, spectroscopic, nonlinear optical parameter, and frontier molecular orbital of 1,3-bis(4-methoxyphenyl)prop-2-en-1-one by DFT/ab initio calculations

Quantum chemical calculations of energies, geometries, and vibrational wavenumbers of 1,3-bis(4-methoxyphenyl)prop-2-en-1-one (C17H16O3) in the ground state were carried out by the using ab initio Hartree−Fock and density functional theory (DFT/B3LYP) methods with the 6-311++G** basis set. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. Theoretical vibrational spectra of the title compound were interpreted by means of potential energies distributions. The theoretical spectrograms for IR spectra of the title compound have been constructed. The analysis of natural bond orbitals shows that the intramolecular hyperconjugative interactions are formed by the orbital overlap between π*(C–C) and π(C–C) bond orbitals, which results in intramolecular charge transfer causing stabilization of the system. The predicted nonlinear optical properties of the title compound are much larger than those of urea. In addition, the analysis of frontier molecular orbitals shows that the title compound has good stability and high chemical hardness.

Experimental spectroscopic (FTIR, FT-Raman, FT-NMR, UV-Visible) and DFT studies of 1-ethyl-1,4-dihydro-7-methyl-4oxo-1,8 napthyridine-3-carboxylic acids

The solid phase FTIR and FT-Raman spectra of 1-ethyl-1,4-dihydro-7-methyl-4oxo-1,8 napthyridine-3-carboxylic acid (EDMONCA) have been recorded in the regions 4000-500 and 4000-400 cm(-1) respectively. The equilibrium geometry, harmonic vibrational frequencies have been investigated by DFT/B3LYP and B3PW91 methods with 6-311G (d,p) basis set. The different between the observed and scaled wave number values of most of the fundamental is very small. The assignments of the vibrational spectra have been carried out with the aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFFM). Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. UV-Visible spectrum of the compound was recorded and the electronic properties HOMO and LOMO energies were measured. The electric dipole moment (μD) and first hyperpolarizability (βtot) values of the investigated molecule were computed using ab initio quantum mechanical calculations. The calculated results also show that the EDMONCA molecule may have microscopic nonlinear optics (NLO) behavior with non-zero values. (1)H and (13)C NMR spectra were recorded and (1)H and (13)C nuclear magnetic resonance chemical shift of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. Thermal stability of EDMONCA was studied by thermogravimetric analysis (TGA). Next Fukui function was calculated to explain the chemical selectivity or reactivity site in EDMONCA. Finally molecular electrostatic potential (MEP) and other molecular properties were performed.

Crystal structure, spectroscopic characterization and density functional studies of (E)-1-((3-methoxyphenylimino)methyl)naphthalen-2-ol

The Schiff base compound (E)-1-((3-methoxyphenylimino)methyl)naphthalen-2-ol was synthesized from the reaction of 2-hydroxy-1-naphthaldehyde with 3-methoxyaniline. The structural properties of the compound has been characterized by using FT-IR, UV-vis and X-ray single-crystal methods. According to X-ray diffraction result, the title compound exists in the phenol-imine tautomeric form. The molecular geometry, vibrational frequencies of the compound in the ground state have been calculated using the density functional theory (DFT/B3LYP) method with the 6-311++G(d,p) basis set, and compared with the experimental data. The obtained results show that the optimized molecular geometry is well reproduce the crystal structure. The theoretical vibrational frequencies are in good agreement with the experimental values. The calculations of electronic absorption spectra of tautomeric forms of the compound were performed by using TD-DFT calculations both in the gas phase and ethanol solvent. To investigate the tautomeric stability, optimization calculations at the B3LYP/6-311++G(d,p) level were performed for the phenol-imine and keto-amine forms of the compound. According to calculated results, the OH form is more stable than NH form. In addition, molecular electrostatic potential (MEP), frontier molecular orbital analysis (HOMO-LUMO), thermodynamic and, non-linear optical (NLO) properties of the compound were investigated using same theoretical calculations.

Study of vibrational spectra, normal coordinate analysis and molecular structure of 6-(2,3-dichlorophenyl)-1,2,4-triazine-3,5-diamine using density functional theory

In the present analysis, the FT-IR, FT-Raman spectra of 6-(2,3-dichlorophenyl)-1,2,4 triazine-3,5-diamine (DCTDA) have been recorded in the region 4000-450 cm(-1) and 4000-100 cm(-1) respectively. The stable structure geometry of the isolated molecule in the gas phase was investigated theoretically using density functional theory (B3LYP) with 6-311G(d,p) basis set. The assignment of the vibrational spectra has been calculated to aid with normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMF). UV-Vis spectra of the compound was recorded in water solvent and the electronic properties, such as HOMO and LUMO energies were calculated by time-dependent density functional theory (TD-DFT) approach. The various intramolecular interactions which are responsible for the stabilization of the molecule were revealed by the natural bond orbital analysis. The molecule orbital contributions are studied by density of energy states (DOS). The other molecular properties like molecular electrostatic potential (MEP), NLO and thermodynamic properties of the title compound at different temperatures have been calculated. Finally the calculation results were applied to stimulate infrared and Raman spectra of the title compound which show good agreement with observed spectra.

Molecular structure, vibrational spectra, NLO and MEP analysis of bis[2-hydroxy-кO-N-(2-pyridyl)-1-naphthaldiminato-кN]zinc(II)

The molecular geometry and vibrational frequencies of bis[2-hydroxy-кO-N-(2-pyridyl)-1-naphthaldiminato-кN]zinc(II) in the ground state have been calculated by using the Hartree-Fock (HF) and density functional method (B3LYP) with 6-311G(d,p) basis set. The results of the optimized molecular structure are presented and compared with the experimental X-ray diffraction. The energetic and atomic charge behavior of the title compound in solvent media has been examined by applying the Onsager and the polarizable continuum model. To investigate second order nonlinear optical properties of the title compound, the electric dipole (μ), linear polarizability (α) and first-order hyperpolarizability (β) were computed using the density functional B3LYP and CAM-B3LYP methods with the 6-31+G(d) basis set. According to our calculations, the title compound exhibits nonzero (β) value revealing second order NLO behavior. In addition, DFT calculations of the title compound, molecular electrostatic potential (MEP), frontier molecular orbitals, and thermodynamic properties were performed at B3LYP/6-311G(d,p) level of theory.

Vibrational spectra, first order hyperpolarizability, NBO, Fukui function and HOMO-LUMO analysis of 2-[4-(1,3-benzodioxol-5-ylmethyl)-1-piperazinyl] pyrimidine

In this work, the vibrational spectral analysis was carried out by using FT-Raman and FT-IR spectroscopy in the range 4000-100cm(-1) and 4000-400cm(-1) respectively, for 2-[4-(1, 3-benzodioxol-5-ylmethyl)-1-piperazinyl] pyrimidine(BDPP) molecule. Theoretical calculations were performed density functional theory (DFT) method using 6-31G(d,p) and 6-311G(d,p) basis sets. The assignments of vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The frontier orbital energy gap and dipole moment illustrates the high reactivity of the title molecule. The first order hyperpolarizability (β0) and related properties (μ, α and Δα) of the title molecule were also calculated. Stability of the molecule has been analyzed by natural bond orbital (NBO) analysis. Global reactivity and local reactivity descriptors of the title molecule have been calculated. Mulliken population analyses on atomic charges of the title compound have been calculated. Finally, molecular electrostatic potential (MEP) and HOMO-LUMO energy levels have been performed.

Quantum chemical studies, natural bond orbital analysis and thermodynamic function of 2,5-dichlorophenylisocyanate

In this work, vibrational spectral analysis on the solid state of 2,5-dichlorophenylisocyanate have been investigated both the experimental and theoretical vibrational data indicate the presence of various functional groups within the title of molecule. The equilibrium geometry, bonding features, harmonic vibrational frequencies, infrared and Raman intensities have been calculated with the help of density functional theory methods. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis following the scaled quantum mechanical force field calculations. The first hyperpolarizability (βtot) of this noval molecular system and related properties (μ, α and Δα) are calculated using B3LYP/6-31+G(d) and B3LYP/6-311++G(d,p) method on the finite-field approach. Second order perturbation energies and electron density in the bonding and anti-bonding orbitals are discussed on the basis of NBO analysis. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule.

FT-IR, FT-Raman spectra and ab initio HF and DFT calculations of 7-chloro-5-(2-chlorophenyl)-3-hydroxy-2,3-dihydro-1H-1,4-benzodiazepin-2-one

The Fourier Transform infrared and Fourier Transform Raman spectra of 7-chloro-5 (2-chlorophenyl)-3-hydroxy-2,3-dihydro-1H-1,4-benzodiazepin-2-one (7C3D4B) were recorded in the regions 4000-400 and 4000-100 cm(-1), respectively. The appropriate theoretical spectrograms for the IR and Raman spectra of the title molecule were also constructed. The calculated results show that the predicted geometry can well reproduce the structural parameters. Predicted vibrational frequencies have been assigned and compared with experimental IR spectra and they supported each other. Stability of the molecule arising from hyperconjugative interactions, charge delocalization and intramolecular hydrogen bond-like weak interaction has been analyzed using natural bond orbital (NBO) analysis by using B3LYP/6-31G(d,p) method. The results show that electron density (ED) in the σ* and π* antibonding orbitals and second-order delocalization energies E(2) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. The first order hyperpolarizability (βtotal) of this molecular system and related properties (β, μ, and Δα) are calculated using HF/6-31G(d,p) and B3LYP/6-31G(d,p) methods based on the finite-field approach.

Identification of structural and spectral features of synthesized cyano-stilbene dye derivatives: a comparative experimental and DFT study

The synthesized three dye derivatives of cyano-stilbene monomer were identified by experimental spectroscopic techniques and density functional approach. The optimized geometrical structure, vibrational and electronic transitions along with the nonlinear optical (NLO) properties of those compounds were presented in this study. The vibrational spectra of investigated compounds were recorded in solid state with FT-IR and FT-Raman spectrometry in the range of 4000-400 cm(-1) and 3600-50 cm(-1), respectively. The theoretical ground state equilibrium conformations and vibrational wavenumbers were carried out by using density functional method with 6-311G(d,p) basis set. Assignments of the fundamental vibrational modes were examined on the basis of the measured data and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The UV absorption spectra of monomers were observed in the range of 200-600 nm in chloroform, acetonitrile and toluene, and time dependent DFT method was used to obtain the electronic properties. The linear polarizability and first hyperpolarizability of the studied molecules indicates that the title compounds can be used as a good nonlinear optical material. A detailed description of spectroscopic behaviors of compounds was given based on the comparison of experimental measurements and theoretical computations.

Vibrational spectra, DFT quantum chemical calculations and conformational analysis of P-iodoanisole

The solid phase FT-IR and FT-Raman spectra of P-iodoanisole (P-IA) have been recorded in the regions 400-4000 and 50-4000 cm(-1), respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by ab initio (HF) and density functional theory (B3LYP) methods with LanL2DZ as basis set. The potential energy surface scan for the selected dihedral angle of P-IA has been performed to identify stable conformer. The optimized structure parameters and vibrational wavenumbers of stable conformer have been predicted by density functional B3LYP method with LanL2DZ (with effective core potential representations of electrons near the nuclei for post-third row atoms) basis set. The nucleophilic and electrophilic sites obtained from the molecular electrostatic potential (MEP) surface were calculated. The temperature dependence of thermodynamic properties has been analyzed. Several thermodynamic parameters have been calculated using B3LYP with LanL2DZ basis set.

Vibrational analysis, electronic structure and nonlinear optical properties of levofloxacin by density functional theory

The Fourier transform (FT-IR) spectrum of Levofloxacin was recorded in the region 4000-400 cm(-1) and a complete vibrational assignment of fundamental vibrational modes of the molecule was carried out using density functional method. The observed fundamental modes have been compared with the harmonic vibrational frequencies computed using DFT (B3LYP) method by employing 6-31 G (d, p) basis sets. The most stable geometry of the molecule under investigation has been determined from the potential energy scan. The first-order hyperpolarizability (βo) and other related properties (μ, αo) of Levofloxacin are calculated using density functional theory (DFT) on a finite field approach. UV-vis spectrum of the molecule was recorded and the electronic properties, such as HOMO and LUMO energies were performed by DFT using 6-31 G (d, p) basis sets. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital analysis (NBO). The calculated HOMO and LUMO energies show that, the charge transfer occurs within the molecule. The other molecular properties like molecular electrostatic potential (MESP), Mulliken population analysis and thermodynamic properties of the title molecule have been calculated.

Molecular structure and spectroscopic characterization of ethyl 4-aminobenzoate with experimental techniques and DFT quantum chemical calculations

The FT-IR and FT-Raman spectra of ethyl 4-aminobenzoate (EAB) in the solid phase were recorded. The fundamental vibrational wavenumbers, intensities of vibrational bands and the optimized geometrical parameters of the compound were evaluated using DFT (B3LYP) method with 6-311++G(d,p) basis set. The stable geometry of the compound was determined from the potential energy surface scan. Complete vibrational assignments and Natural Bond Orbital (NBO) analysis for the title compound were carried out. The assignments of the vibrational spectra were carried out with the help of normal co-ordinate analysis (NCA) following the Scaled Quantum Mechanical Force Field (SQMFF) methodology. The molecule orbital contributions were studied by using the total (TDOS), partial (PDOS), and overlap population (OPDOS) density of states. UV-visible spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies were performed by time-dependent DFT (TD-DFT) approach. Mulliken population analysis on atomic charges were also calculated. Besides, molecular electrostatic potential (MEP) and thermodynamic properties were performed.

Electronic absorption, vibrational spectra, nonlinear optical properties, NBO analysis and thermodynamic properties of N-(4-nitro-2-phenoxyphenyl) methanesulfonamide molecule by ab initio HF and density functional methods

In this work, the vibrational spectral analysis was carried out by using FT-Raman and FT-IR spectroscopy in the range 4000-100 cm(-1) and 4000-400 cm(-1), respectively, for N-(4-nitro-2-phenoxyphenyl) methanesulfonamide molecule. Theoretical calculations were performed by ab initio RHF and density functional theory (DFT) method using 6-31G(d,p) and 6-311G(d,p) basis sets. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The frontier orbital energy gap and dipole moment illustrates the high reactivity of the title molecule. The first order hyperpolarizability (β0) and related properties (μ, α and Δα) of the molecule were also calculated. Stability of the molecule arising from hyperconjugative interactions and charge delocalization were analyzed using natural bond orbital (NBO) analysis. The results show that electron density (ED) in the σ(*) and π(*) anti-bonding orbitals and second order delocalization energies (E2) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. UV-vis spectrum of the compound was recorded in the region 200-500 nm in ethanol and electronic properties such as excitation energies, oscillator strength and wavelength were calculated by TD-DFT/B3LYP, CIS and TD-HF methods using 6-31G(d,p) basis set. Molecular electrostatic potential (MEP) and HOMO-LUMO energy levels are also constructed. The thermodynamic properties of the title compound were calculated at different temperatures and the results reveals the heat capacity (C), and entropy (S) increases with rise in temperature.

Experimental and theoretical investigations of spectroscopic properties of 8-chloro-1-methyl-6-phenyl-4H-[1,2,4]triazolo[4,3-a][1,4]benzodiazepine

The Fourier transform infrared (FTIR) and FT-Raman spectra of 8-chloro-1-methyl-6-phenyl-4H-[1,2,4]triazolo[4,3-a][1,4]benzodiazepine (8C1M6PB) have been recorded in the range of 4000-400 and 4000-100 cm(-1), respectively. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated potential energy distribution (PED). The equilibrium geometries, harmonic frequencies, infrared intensities and Raman scattering activities were calculated by Hartree-Fock (HF) and density functional B3LYP method with the 6-31G (d,p) basis set. The vibrational frequencies were calculated in all these methods and were compared with the experimental frequencies which yield good agreement between observed and calculated frequencies. The first order hyperpolarizability (βtotal) of this molecular system and related properties (β, μ, and Δα) are calculated using HF/6-31G (d,p) and B3LYP/6-31G(d,p) methods based on the finite-field approach. The calculated Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energies show that charge transfer occurs in the molecule. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Conformation analysis was carried for 8C1M6PB by Potential energy surface scan to find all possible conformers with B3LYP method using 6-31G (d,p) basis set. The entropy of the title compound is also performed at HF/6-31G (d,p) and B3LYP/6-31G(d,p) levels of theory. In addition, the thermodynamic properties of the compound were calculated at different temperatures and corresponding relations between the properties and temperature were also studied.

Molecular structural, non-linear optical, second order perturbation and Fukui studies of Indole-3-Aldehyde using density functional calculations

Indole-3-Aldehyde is a new organic non-linear material having good second harmonic generation. The optimized molecular geometry, harmonic vibrational frequencies, infrared intensities of Indole-3-Aldehyde (I3A, C9H7NO) in the ground state were carried out by using density functional theory (B3LYP) method with 6-31G(d,p) basis set. A detailed interpretation of the infrared spectrum of Indole-3-Aldehyde is reported. The vibrational frequencies are calculated and compared with experimental FT-IR spectra. The theoretical spectrograms of FT-IR of the title compound have been constructed in addition, theoretical information like ONIOM, potential energy surface, NBO, and Fukui function are also calculated. Unambiguous vibrational assignment of all the fundamentals was made using the potential energy distribution.

Computational and spectroscopic studies of a new Schiff base 3-hydroxy-4-methoxybenzylidene(2-hydroxyphenyl)amine and molecular structure of its corresponding zwitterionic form

Computational and spectroscopic properties of a novel Schiff base compound, 3-hydroxy-4-methoxybenzylidene(2-hydroxyphenyl)amine were studied. The crystal structures of the title compound and its corresponding zwitterionic form were analyzed by X-ray diffraction. The presence of N-H, C-O and C=N stretching vibrations in IR spectrum strongly suggest that the title compound has zwitterionic form in the solid state. Molecular geometry of the title compound in the ground state has been calculated using the density functional method (DFT) at B3LYP 6-31++G(d,p) basis set and was compared with the experimental data. The calculated results of the title compound show that the optimized geometry can well reproduce the crystal structure. The molecule shows absorption bands at 345 and 363 nm in EtOH. The shoulder-shaped bands at 415 nm can be assigned to n→π(*) transitions. The absorption band is observed at 285 nm in EtOH corresponds to the π→π(*) transitions.

Conformational stability, vibrational spectra, molecular structure, NBO and HOMO-LUMO analysis of 5-nitro-2-furaldehyde oxime based on DFT calculations

The FTIR and FT-Raman spectra of 5-nitro-2-furaldehyde oxime (NFAO) have been recorded in the regions 4000-400 cm(-1) and 3500-50 cm(-1), respectively. The total energies of different conformations have been obtained from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The computational results identify the most stable conformer of NFAO as the C1 form. Utilizing the observed FTIR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of the compound were carried out. The optimum molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, were calculated by density functional theory (DFT/B3LYP) method with 6-31+G(d,p) and 6-311++G(d,p) basis sets. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. A detailed interpretation of the infrared and Raman spectra of NFAO is also reported based on total energy distribution (TED). Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. Besides, molecular electrostatic potential (MEP), HOMO and LUMO analysis, and several thermodynamic properties were performed by the DFT method. Mulliken's net charges have been calculated and compared with the natural atomic charges. Ultraviolet-visible spectrum of the title molecule has also been calculated using TD-DFT method.

Ab initio and density functional theory studies on vibrational spectra of 3-hydroxy-3-(2-methyl-1H-indol-3-yl)indolin-2-one

Computational studies have been carried out on 3-hydroxy-3-(2-methyl-1H-indol-3-yl) indolin-2-one (HMI) using both the DFT-B3LYP/6-311+G and HF/6-311+G methods. The optimized geometry of HMI and its bonding parameters as well as IR spectra have been calculated and analyzed. It can be seen that the calculated bond lengths are in good agreement with the reported bond lengths of indole and isatins. The calculated spectra have been compared with the available experimental FT-IR spectra. From vibrational frequency analysis, it can be seen that the vibrational frequencies obtained from B3LYP method are in good agreement with the experiment, when compared to HF method and there is an excellent correlation with the 0.999 regression coefficient between the experimental and calculated vibrations for HMI. The geometrical parameters, non-linear optical properties and thermodynamic properties are calculated and reported.

Structural, electronic, thermodynamical and charge transfer properties of Chloramphenicol Palmitate using vibrational spectroscopy and DFT calculations

The global problem of advancing bacterial resistance to newer drugs has led to renewed interest in the use of Chloramphenicol Palmitate (C27H42Cl2N2O6) [Palmitic acid alpha ester with D-threo-(-),2-dichloro-N-(beta-hydroxy-alpha-(hydroxymethyl)-p-nitrophenethyl)acetamide also known as Detereopal]. The characterization of the three polymorphic forms of Chloramphenicol Palmitate (CPP) was done spectroscopically by employing FT-IR and FT-Raman techniques. The equilibrium geometry, various bonding features, and harmonic wavenumbers have been investigated for most stable form A with the help of DFT calculations and a good correlation was found between experimental data and theoretical values. Electronic properties have been analyzed employing TD-DFT for both gaseous and solvent phase. The theoretical calculation of thermodynamical properties along with NBO analysis has also been performed to have a deep insight into the molecule for further applications.

FT-IR, FT-Raman and UV spectral investigation: computed frequency estimation analysis and electronic structure calculations on 1-bromo-2-methylnaphthalene

In this work, the vibrational spectral analysis was carried out by using FT-Raman and FT-IR spectroscopy in the range 100-4000 cm(-1) and 400-4000 cm(-1) respectively, for 1-bromo-2-methylnaphthalene (C11H9Br) molecule. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based density functional theory (DFT) and ab initio HF methods with different basis sets combinations. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The results of the calculations were applied to simulated vibrational spectra of the title compound, which show excellent agreement with observed spectra. The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other methods. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) complements with the experimental findings. In addition, molecular electrostatic potential and nonlinear optical and thermodynamic properties of the title compound were performed. Mulliken charges and NBOs of the title molecule were also calculated and interpreted.

The effect of C-vacancy on hydrogen storage and characterization of H2 modes on Ti functionalized C60 fullerene a first principles study

Density functional theory calculations were performed to examine the effect of a C vacancy on the physisorption of H(2) onto Ti-functionalized C(60) fullerene when H(2) is oriented along the x-, y-, and z-axes of the fullerene. The effect of the C vacancy on the physisorption modes of H(2) was investigated as a function of H(2) binding energy within the energy window (-0.2 to -0.6 eV) targeted by the Department of Energy (DOE), and as functions of a variety of other physicochemical properties. The results indicate that the preferential orientations of H(2) in the defect-free (i.e., no C vacancy) C(60)TiH(2) complex are along the x- and y-axes of C(60) (with adsorption energies of -0.23 and -0.21 eV, respectively), making these orientations the most suitable ones for hydrogen storage, in contrast to the results obtained for defect-containing fullerenes. The defect-containing (i.e., containing a C vacancy) C(59)TiH(2) complex do not exhibit adsorption energies within the targeted energy range. Charge transfer occurs from Ti 3d to C 2p of the fullerene. The binding of H(2) is dominated by the pairwise support-metal interaction energy E(i)(Cn...Ti), and the role of the fullerene is not restricted to supporting the metal. The C vacancy enhances the adsorption energy of Ti, in contrast to that of H(2). A significant reduction in the energy gap of the pristine C(60) fullerene is observed when TiH(2) is adsorbed by it. While the C( n ) fullerene readily participates in nucleophilic processes, the adjacent TiH(2) fragment is available for electrophilic processes.

Synthesis, structure, photo-responsive properties of 4-(2-fluorobenzylideneamino)antipyrine: a combined experimental and theoretical study

In this work, 4-(2-fluorobenzylideneamino)antipyrine (FBIAAP) was synthesized and characterized by elemental analysis, XRD, FT-IR, FT-Raman and UV-Vis techniques as well as density functional calculations. The studied molecule adopts a trans configuration about the imine CN bond, and adjacent molecules are linked through two kinds of weak hydrogen bonds to form supramolecular layered structures along the ab plane. Vibrational spectral analyses show that the benzene moiety directly attached to the central pyrazoline shows good vibrational isolation from the other moiety of pyrazole-imino-benzene presenting good vibrational resonances. UV-vis absorption bands mainly belong to n→π and π→π according to the electron transfer orbital assignments for the electron absorption spectrum of FBIAAP. The first-order hyperpolarizability of FBIAAP is 44.9 times that of urea theoretically. In addition, the thermodynamic properties were also obtained theoretically from the harmonic frequencies of the optimized structure.

Spectroscopic (FT-IR, FT-Raman, UV and NMR) investigation and NLO, HOMO-LUMO, NBO analysis of organic 2,4,5-trichloroaniline

In this work, the experimental and theoretical study on the molecular structure and vibrational spectra of 2,4,5-trichloroaniline (C(6)H(4)NCl(3), abbreviated as 2,4,5-TClA) were studied. The FT-IR and FT-Raman spectra were recorded. The molecular geometry and vibrational frequencies in the ground state were calculated by using the Hartree-Fock (HF) and density functional theory (DFT) methods (B3LYP) with 6-311++G(d,p) basis set. Comparison of the observed fundamental vibrational frequencies of 2,4,5-TClA with calculated results by HF and DFT indicates that B3LYP is superior to HF method for molecular vibrational problems. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The theoretically predicted FT-IR and FT-Raman spectra of the title molecule have been constructed. A study on the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. Besides, molecular electrostatic potential (MEP) and thermodynamic properties were performed. The electric dipole moment (μ) and the first hyperpolarizability (β) values of the investigated molecule were computed using ab initio quantum mechanical calculations. The calculated results also show that the 2,4,5-TClA molecule may have microscopic nonlinear optical (NLO) behavior with non-zero values. Mulliken atomic charges of 2,4,5-TClA was calculated and compared with aniline and chlorobenzene molecules. The (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results.

FT-IR and FT-Raman spectra, thermo dynamical behavior, HOMO and LUMO, UV, NLO properties, computed frequency estimation analysis and electronic structure calculations on α-bromotoluene

In this work, the vibrational spectral analysis was carried out by using Raman and infrared spectroscopy in the range 100-4,000 cm(-1) and 50-4,000 cm(-1), respectively, for the title molecules. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on Hartee Fock (HF) and density functional theory (DFT) method and different basis sets combination. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other methods. The calculated HOMO and LUMO energies show that charge transfer occurs within molecule. The influences of bromine atom and methyl group on the geometry of benzene and its normal modes of vibrations have also been discussed. The results of the calculations were applied to simulated spectra of the title compounds, which show excellent agreement with observed spectra.

Structural, proton-transfer, thermodynamic and nonlinear optical studies of (E)-2-((2-hydroxyphenyl)iminiomethyl)phenolate

Recently, the study of imine-bridged organics is interested in proton-transfer and photo-responsive material fields. Herein, we make a investigation on the structural, thermodynamic and nonlinear optical properties of (E)-2-((2-hydroxyphenyl)iminiomethyl)phenolate (HPIMP). The structural varieties of the studied compound are characterized by the X-ray single crystal diffraction and vibrational spectral techniques, as well as the vibrational spectral bands are precisely ascribed to the studied structure with the aid of DFT theoretical calculations. The experimental results of the FT-IR and X-ray measurements supply good proofs to reveal the proton-transfer procedures of HPIMP, and exhibit that the studied compound is a good proton-transfer model. In addition, the thermodynamic properties are obtained from the theoretical vibrations of the optimized HPIMP. The linear polarizability (α(0)) and first-order hyperpolarizabilities (β(0)) respectively present the values of 26.28 Å(3) and 7.41×10(-30) cm(5)/esu predicated theoretically by the DFT-B3lYP method at 6-31G(d) level, which indicates that the studied compound is a promising nonlinear optical material candidate.

Analysis of vibrational spectra (FT-IR and FT-Raman) and nonlinear optical properties of organic 2-chloro-p-xylene

In this work, the vibrational spectral analysis was carried out by using FT-Raman and FT-IR spectroscopy in the range 100-4000cm(-1) and 400-4000cm(-1) respectively, for the title molecule. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on Hartree-Fock (HF) and density functional theory (DFT) method with 6-311++G(d,p) basis set. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other method. The influences due to the substitution of halogen bond and methyl group were investigated. The results of the calculations are applied to simulate the vibrational spectra of the title compound, which show excellent agreement with observed spectra. The absorption energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT). Besides, frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP), and thermodynamic properties were performed. Mulliken charges of the title molecule were also calculated and interpreted. The dipole moment, linear polarizability and first hyperpolarizability values were also computed.

Vibrational spectroscopic studies, NLO, HOMO-LUMO and electronic structure calculations of α,α,α-trichlorotoluene using HF and DFT

FT-IR and FT-Raman spectra of α,α,α-trichlorotoluene have been recorded and analyzed. The geometry, fundamental vibrational frequencies are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) B3LYP/6-311++G(d,p) method and a comparative study between HF level and various basis sets combination. 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 complete vibrational assignments of wavenumbers are made on the basis of potential energy distribution (PED). The effects due to the substitutions of methyl group and halogen were investigated. The absorption energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT). The electric dipole moment, polarizability and the first hyperpolarizability values of the α,α,α-trichlorotoluene have been calculated. (1)H NMR chemical shifts were calculated by using the gauge independent atomic orbital (GIAO) method with HF and B3LYP methods with 6-311++G(d,p) basis set. Moreover, molecular electrostatic potential (MEP) and thermodynamic properties were performed. Mulliken and natural charges of the title molecule were also calculated and interpreted.

Vibrational spectroscopic investigation on the structure of 2-ethylpyridine-4-carbothioamide

Fourier transform Raman and Fourier transform infrared spectra of 2-ethylpyridine-4-carbothioamide were recorded in the regions 3600-100 cm(-1) and 4000-450 cm(-1), respectively in the solid phase. 2-Ethylpyridine-4-carbothioamide is used as anti-tubercular agent that inhibits mycolic acid synthesis. The equilibrium geometry harmonic vibrational frequencies, infrared intensities and Raman scattering activities were calculated by Hartee Fock and density functional B3LYP methods with 6-31 G (d,p) basis set, using Gaussian 03 W program package on a Pentium IV/1.6 GHz personal computer(.) A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated potential energy distribution (PED). The thermodynamic functions of the title compound were also performed at the above methods and basis set. A detailed interpretation of the infrared and Raman spectra of 2-ethylpyridine-4-carbothioamide is reported. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecules were calculated using the GIAO method confirms with the experimental values. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The linear polarizability (α) and the first order hyperpolarizability (β) values of the investigated molecule have been computed using DFT quantum mechanical calculations. The HOMO and LUMO energy gap reveals that the energy gap reflects the chemical activity of the molecule. The observed and calculated wave numbers are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed spectra.

A comparative study on vibrational, conformational and electronic structure of α,α'-diol-o-xylene, α,α'-diol-m-xylene and α,α'-diol-p-xylene

The Fourier transform infrared (FTIR) and FT-Raman spectra of α,α'-diol-o-xylene (DOLOX), α,α'-diol-m-xylene (DOLMX) and α,α'-diol-p-xylene (DOLPX) of the configuration HOCH(2)-C(6)H(4)-CH(2)OH have been recorded in the range 4000-400 and 4000-100 cm(-1), respectively. The most stable geometry of the compounds was determined by conformational analysis. The complete vibrational assignment and analysis of the fundamental modes of the most stable conformer of the compounds were carried out using the experimental FTIR and FT-Raman data and quantum chemical studies. The observed vibrational frequencies were compared with the wavenumbers derived theoretically for the optimised geometry of the compounds from the DFT-B3LYP gradient calculations employing the standard 6-31G** and high level and 6-311++G** basis sets. The structural parameters and vibrational wavenumbers obtained from the DFT method are in good agreement with the experimental data. The potential energy distributions of the fundamental modes were also calculated by Wilson's FG matrix method. The effect of -CH(2)OH groups on the skeletal vibrations have been discussed. The intra molecular n→σ* and π→π* interactions were discussed with NBO analysis.

Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, 13C, 1H, UV) study, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 4-[(4-aminobenzene) sulfonyl] aniline by ab initio HF and density functional method

The Fourier transform infrared (FT-IR) and FT-Raman of 4-[(4-aminobenzene) sulfonyl] aniline have been recorded and analyzed. The equilibrium geometry, harmonic vibrational frequencies have been investigated with the help of HF and DFT methods with 6-31G(d,p) as basis set. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated potential energy distribution (PED). The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by GIAO method. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The linear polarizability (α) and the first order hyperpolarizability (β) values of the investigated molecule have been computed using DFT quantum mechanical calculations. UV-vis spectrum of the compound was recorded and electronic properties, such as HOMO and LUMO energies were also performed. Finally the calculations results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra.

The spectroscopic (FTIR, FT-Raman, NMR and UV), first-order hyperpolarizability and HOMO-LUMO analysis of methylboronic acid

The solid phase FTIR and FT-Raman spectra of methylboronic acid (MBA) have been recorded in the regions 400-4000 and 50-4000 cm(-1), respectively. The spectra were interpreted interms of fundamentals modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (B3LYP) and HF method with 6-311++G(d,p) as basis set. The vibrational frequencies were calculated for most stable conformer and were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. The infrared and Raman spectra were also predicted from the calculated intensities. (1)H and (13)C NMR spectra were recorded and (1)H and (13)C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compound was recorded in the region 200-400 nm and the electronic properties HOMO and LUMO energies were calculated by time-dependent TD-DFT approach. Mulliken charges of the MBA molecule was also calculated and interpreted. The geometric parameters, energies, harmonic vibrational frequencies, IR intensities, Raman intensities and absorption wavelengths were compared with the available experimental data of the molecule.

FT-IR, FT-Raman and UV spectral investigation: computed frequency estimation analysis and electronic structure calculations on chlorobenzene using HF and DFT

In this work, the vibrational spectral analysis was carried out by using FT-Raman and FT-IR spectroscopy in the range 100-4000 cm(-1) and 400-4000 cm(-1) respectively, for the title molecule. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on Hartree Fock (HF) and density functional theory (DFT) method and different basis sets combination. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other methods. The effects due to the substitution of halogen bond were investigated. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) results complements with the experimental findings. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP), and thermodynamic properties were performed. The thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations between heat capacity (C), entropy (S), and enthalpy changes (H) and temperatures.

Experimental, quantum chemical and natural bond orbital investigations of N-(2,4-dimethylphenyl)-2,2-dichloroacetamide and N-(3,5-dimethylphenyl)-2,2-dichloroacetamide

N-(2,4-Dimethylphenyl)-2,2-dichloroacetamide (24DMPA) and N-(3,5-dimethylphenyl)-2,2-dichloroacetamide (35DMPA) of the configuration X(y)C(6)H(5-y)NHCO-CHCl(2) (where, X=CH(3) and y=2) were synthesised and an extensive spectroscopic investigations have been carried out. The ab initio and DFT studies were carried out with 6-31G** and cc-pVDZ basis sets to determine the structural, thermodynamical and vibrational characteristics of the compounds and also to understand the steric influence of methyl groups on the characteristic frequencies of amide (-CONH-) group. The most stable conformer has been determined by PES scan. Normal co-ordinate analysis has been carried out in an effort to provide mixing of the fundamental modes with the help of potential energy distribution (PED). The energies of the frontier molecular orbitals have been determined. Complete NBO analysis was also carried out to find out the intramolecular electronic interactions and their stabilisation energy. All the computed values are well agreed with the experimental data.