Vibrational spectroscopy investigation using ab initio and density functional theory analysis on the structure of 3-(6-benzoyl-2-oxobenzo[d]oxazol-3(2H)-yl)propanoic acid

Synthesis, characterization, and DFT studies of a new chiral ionic liquid from (S)-1-phenylethylamine

A new chiral ionic liquid was synthesized from (S)-1-phenylethylamine and it was studied by IR, Raman, polarimetry, NMR and X-ray crystal diffraction. Its vibrational spectral bands are precisely ascribed to the studied structure with the aid of DFT theoretical calculations. The optimized geometries and calculated vibrational frequencies are evaluated via comparison with experimental values. The vibrational spectral data obtained from IR and Raman spectra are assigned based on the results of the theoretical calculations by the DFT-B3LYP method at 6-311G(d,p) level. The computed vibrational frequencies were scaled by scale factors to yield a good agreement with observed experimental vibrational frequencies.The vibrational modes assignments were performed by using the animation option of GaussView5.0 graphical interface for Gaussian program.

FT-IR, HF and DFT structural, vibrational analysis of 5-chloro-3-(2-(4-ethylpiperazin-1-yl)-2-oxoethyl)benzo[d]thiazol-2(3H)-one molecule

The optimized molecular geometry, vibrational frequencies, atomic charges, dipole moment, rotational constants and several thermodynamic parameters of 5-chloro-3-(2-(4-ethylpiperazin-1-yl)-2-oxoethyl)benzo[d]thiazol-2(3H)-one (abbreviated as CEOT) molecule in the ground state were calculated using ab initio Hartree-Fock (HF) and Density Functional B3LYP methods (DFT) with 6-311++G(d,p), 6-311G(d,p), 6-31++G(d,p) and 6-31G(d,p) basis sets. The Fourier-transform infrared (FT-IR) spectrum of CEOT has been recorded in the region 4000-400 cm(-1). The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR spectrum. Energy gap of the molecule was found using HOMO and LUMO calculation, hence the less band gap, which seems to be more stable. The observed and calculated vibrational frequencies are found to be in good agreement.

FT-IR, FT-Raman and DFT quantum chemical study on the molecular conformation, vibrational and electronic transitions of 1-(m-(trifluoromethyl)phenyl)piperazine

The FTIR and FT-Raman spectra of 1-(m-(trifluoromethyl)phenyl)piperazine [TFMPP] have been recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The optimized geometry, frequency and intensity of the vibrational bands of the compound was obtained by the density functional theory using 6-311++G(d,p) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. A detailed interpretation of the infrared and Raman spectra were also reported based on potential energy distribution (PED). UV-Vis spectrum of the compound was recorded and the electronic properties HOMO and LUMO energies were measured by TD-DFT approach. Furthermore, molecular electrostatic potential is performed and also the calculated HOMO and LUMO energies show that charge transfer occurs within the molecule.

Synthesis, structure and photoresponsive properties of 4-(3-fluorobenzylideneamino)antipyrine

Organic compounds are attracting greater attention largely in the recent years owing to their potential applications in the functional materials. Herein we reported the structural and photophysical properties of 4-(3-fluorobenzylideneamino)antipyrine. The studied molecule adopts a trans configuration about the imine bond, and forms a non-planar molecular device consisted of two effectively conjugated π-electron moieties. The stronger vibrational and nonlinear optical activities are tightly related to the molecular structural characteristics revealed by the analysis on vibrational modes and frontier molecular orbitals. The intramolecular electrons can be separated by the electron-transporting with specified photon-absorbing theoretically. The total molecular dipole moment, mean linear polarizability and first-order hyperpolarizability calculated at B3LYP/6-31G(d) level are 1.5390 Debye, 35.6075 Å(3) and 1.5391×10(-29) cm(5)/esu, respectively. The reported results indicate that the compound is a promising candidate of photoresponsive materials.

The molecular structure and vibrational spectra of N-(3-tert-butyl-2-hydroxybenzylidene)-2,6-diphenyl-4-hydroxyaniline

The molecular structure, vibrational frequencies and intensities of N-(3-tert-butyl-2-hydroxybenzylidene)-2,6-diphenyl-4-hydroxyaniline were calculated by the Density Functional Theory methods (BLYP, B3PW91 and B3LYP) using the 6-31G(d,p) basis set. The calculated geometric parameters were compared to the corresponding X-ray structure of the title compound. The comparison of the theoretical and experimental geometry of the title compound shows that the X-ray parameters fairly well reproduce the geometry of optimized by B3LYP method (r=0.9825). The harmonic vibrations computed for this compound by the B3LYP/6-31G(d,p) method are in good agreement with the observed IR and Raman spectral data. The root mean square values error of the observed and calculated IR bands are found to be 9.80, 9.40 and 8.42 for B3LYP, B3PW91 and BLYP/6-31G(d,p) methods, respectively. Theoretical vibrational spectra of the title compound were interpreted by means of PEDs using the SQM 2.0 program. A general better performance of the investigated methods was calculated by PAVF 1.0 program.

Vibrational Spectroscopy Investigation Using Ab Initio and Density Functional Theory Analysis on the Structure oftert-Butyl 3a-Chloroperhydro-2,6a-epoxyoxireno[e]isoindole-5-carboxylate

The molecular structure, vibrational frequencies, and infrared intensities of thetert-butyl 3a-chloroperhydro-2,6a-epoxyoxireno[e]isoindole-5-carboxylate were calculated by the HF and DFT (BLYP and B3LYP) methods using 6-31G(d) and 6-31G(d,p) basis sets. The FT infrared spectrum of the solid sample was measured under standard condition. We obtained two stable conformers for the title compound; however Conformer 1 is approximately 0.2 kcal/mol more stable than the Conformer 2. The comparison of the theoretical and experimental geometry of the title compound shows that the X-ray parameters fairly well reproduce the geometry of Conformer 2. Comparison of the observed fundamental vibrational frequencies of the title molecule and calculated results by HF and DFT methods indicates that B3LYP is superior for molecular vibrational problems. The harmonic vibrations computed by the B3LYP/6-31G(d,p) method are in a good agreement with the observed IR spectral data. Theoretical vibrational spectra of the title compound were interpreted by means of potential energy distributions (PEDs) using VEDA 4 program.

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.

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.

Structure and vibrational spectra of 6-(4-fluorobenzoyl)-3-(2-(4-methylpiperazin-1-yl)-2-oxoethyl)benzo[d]thiazol-2(3H)-one molecule

The molecular structure, conformational stability and vibrational frequencies of 6-(4-fluorobenzoyl)-3-(2-(4-methylpiperazin-1-yl)-2-oxoethyl)benzo[d]thiazol-2(3H)-one (abbreviated as FMOT) molecule in the ground state were calculated by DFT (B3LYP) and HF methods using different basis sets. The solid-state FT-IR spectrum was measured and compared with calculated values. FMOT was found to have four different stable conformations. The comparison of the theoretical and experimental geometries of the title compound indicated that the X-ray parameters fairly well agree with the theoretically obtained values for the most stable conformer. Energy gap of the molecule was found using HOMO and LUMO calculation, hence the less band gap, which seems to be more stable. The observed and calculated vibrational frequencies are found to be in good agreement.

Synthesis, vibrational spectral and nonlinear optical studies of N-(4-hydroxy-phenyl)-2-hydroxybenzaldehyde-imine: a combined experimental and theoretical investigation

The study of imine-bridged organics has been the one hot spot of photo-responsive material sciences in recent years. Herein we make a study of the synthesis, characteristics and potential application of N-(4-hydroxy-phenyl)-2-hydroxy-benzaldehyde-imine (HPHBI), C13H11NO2. The studied compound was synthesized in one step by the condensation reaction of salicylaldehyde and 4-aminophenol in methanol solution, and characterized by single crystal X-ray diffraction, FT-IR and FT-Raman techniques with theoretical calculations at B3LYP/6-31G(d) level. The molecule adopts trans configuration about central CN bond with intramolecular hydrogen bonding, and the adjacent molecules form wave-shaped structure linked by strong intermolecular hydrogen bonding mechanism along b axis. The vibrational spectra have been precisely assigned with the aid of theoretical frequencies. Furthermore, the thermodynamic properties have been obtained by the theoretical vibrational analysis for HPHBI. The total linear polarizability and first-order hyperpolarizabilities calculated on the studied compound respectively present 25.378 Å3 and 1.655×10(-29) cm5/esu, which indicates the compound has relatively good nonlinear optical property.

Vibrational spectroscopic (FTIR and FTRaman) investigation using ab initio (HF) and DFT (LSDA and B3LYP) analysis on the structure of Toluic acid

The FTRaman and FTIR spectra for Toluic acid (TA) have been recorded in the region 4000-100 cm(-1) and compared with the harmonic vibrational frequencies calculated using HF/DFT (LSDA and B3LYP) method BY employing 6-311G (d, p) basis set with appropriate scale factors. IR intensities and Raman activities are also calculated by HF and DFT (LSDA/B3LYP) methods. Optimized geometries of the molecule have been interpreted and compared with the reported experimental values for benzoic acid and some substituted benzoic acids. The experimental geometrical parameters show satisfactory agreement with the theoretical prediction from HF and DFT. The scaled vibrational frequencies at B3LYP/6-311G (d, p) seem to coincide with the experimentally observed values with acceptable deviations. The theoretical spectrograms (IR and Raman) have been constructed and compared with the experimental FT-IR and FT-Raman spectra. Some of the vibrational frequencies of the TA are effected upon profusely with the methyl substitutions in comparison to benzoic acid and these differences are interpreted.

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

Three antipyrine derivatives of o-, m- and p-chlorobenzylideneaminoantipyrines were characterized by spectral techniques and density functional calculations. The optimized configurations are very close to the XRD values and are used as foundations to investigate the molecular properties. The spectral assignments were attempted to ascribe to the vibrational modes of the detailed substructures with the aid of theoretical calculations because of the satisfactory consistencies between the experimental and theoretical spectra for each of the studied compounds. Raman spectral ascriptions represent that the pi-conjugated moieties linked by Schiff base imines are responsible for the excellent Raman scattering activities of these compounds. The linear polarizabilities and first hyperpolarizabilities of the studied molecules indicate that the compounds are good candidates of nonlinear optical materials. The statistical thermodynamic functions and their correlations with temperatures obtained from the theoretical vibrations are similar to each other among the isomers.

Vibrational spectroscopic study of o-, m- and p-hydroxybenzylideneaminoantipyrines

Three structurally similar antipyrine derivatives of o-hydroxybenzylideneaminoantipyrine (o-HBAP), m-hydroxybenzylideneaminoantipyrine (m-HBAP) and p-hydroxybenzylideneaminoantipyrine (p-HBAP) were characterized by FT-IR, FT-Raman experimental techniques and density functional theoretical (DFT) calculations. The comparisons between the calculated and experimental results covering molecular structures, assignments of fundamental vibrational modes and thermodynamic properties were investigated. The optimized molecular geometries agree well with the corresponding experimental values by comparing with the XRD data. The comparisons and assignments of the vibrational frequencies indicate that the experimental spectra also coincide satisfactorily with those of theoretically simulated spectrograms except the hydrogen-bond coupling infrared vibrations, and compounds can be distinguished by the IR and Raman spectra due to the differences of the hydroxyl-substituted positions and molecular packing, and the strong Raman scattering activities of the compounds are tightly relative to the molecular conjugative moieties linked through the Schiff base imines. The thermodynamic functions and their correlations with temperatures were also obtained from the theoretical harmonic frequencies.

Experimental and theoretical studies on vibrational spectra of 4-(2-furanylmethyleneamino)antipyrine, 4-benzylideneaminoantipyrine and 4-cinnamilideneaminoantipyrine

This work deals with the IR and Raman spectroscopy of 4-(2-furanylmethyleneamino) antipyrine (FAP), 4-benzylideneaminoantipyrine (BAP) and 4-cinnamilideneaminoantipyrine (CAP) by means of experimental and quantum chemical calculations. The equilibrium geometries, harmonic frequencies, infrared intensities and Raman scattering activities were calculated by density functional B3LYP method with the 6-31G(d) basis set. The comparisons between the calculated and experimental results covering molecular structures, assignments of fundamental vibrational modes and thermodynamic properties were investigated. The optimized molecular geometries have been compared with the experimental data obtained from XRD data, which indicates that the theoretical results agree well with the corresponding experimental values. For the three compounds, comparisons and assignments of the vibrational frequencies indicate that the calculated frequencies are close to the experimental data, and the IR spectra are comparable with some slight differences, whereas the Raman spectra are different clearly and the strongest Raman scattering actives are relative tightly to the molecular conjugative moieties linked through their Schiff base imines. The thermodynamic properties (heat capacities, entropies and enthalpy changes) and their correlations with temperatures were also obtained from the harmonic frequencies of the optimized structures.

Experimental and theoretical studies on 4-(2,4-dichlorobenzylideneamino)antipyrine and 4-(2,6-dichlorobenzylideneamino)antipyrine

Two antipyrine derivates, with the same formula C(18)H(15)Cl(2)N(3)O, are structurally similar Schiff bases derived from the condensation of 2,4-dichlorobenzaldehyde or 2,6-dichlorobenzaldehyde and 4-aminoantipyrine in methanol solutions. The compounds were characterized by elemental analysis, FT-IR, FT-Raman and UV-vis techniques. Density functional calculations were performed to further optimize and characterize them. The calculated results indicate that the theoretical values show good agreements with experimental ones. They are similar in their IR spectra and different in their Raman spectra. The detailed vibrational and UV-vis absorption spectra of the compounds have been ascribed to their corresponding molecular structures and electrons orbital transitions. The statistical thermodynamic functions and their correlations with temperatures of the title compounds have been obtained from their theoretical vibrations of the optimized structures. The nonlinear optical and UV-vis properties indicate that the compounds are the promising photoelectronic materials.

Experimental and density functional theory and ab initio Hartree-Fock study on the vibrational spectra of 5-chloro-6-(4-chlorobenzoyl)-2-benzothiazolinone molecule

The vibrational frequencies and infrared intensities of 5-chloro-6-(4-chlorobenzoyl)-2-benzothiazolinone (abbreviated as CCB) molecule in the ground state were calculated by HF and DFT (B3LYP and BLYP) methods using different basis sets to elucidate the molecular structure. The solid-state FT-IR spectrum was measured and compared with calculated values. CCB was found to have two different stable conformations. The dihedral angles alpha and beta (i.e. C9-C8-C12-C18 and C8-C12-C18-C17, respectively) were computed as -59.6 degrees and -14.5 degrees for the most stable conformer. The comparison of the theoretical and experimental geometries of the title compound indicated that the X-ray parameters fairly well agree with the theoretically obtained values for the most stable conformer. The calculated vibrational frequencies are also in good agreement with the experimental results.

The molecular structure and vibrational spectra of N-(2,2-diphenylacetyl)-N'-(naphthalen-1yl)-thiourea by Hartree-Fock and density functional methods

N-(2,2-Diphenylacetyl)-N'-(naphthalen-1yl)-thiourea (PANT) has been synthesized and characterized by elemental analysis, IR spectroscopy and (1)H NMR spectroscopy. The crystal and molecular structure of the title compound has been determined from single crystal X-ray diffraction data. It crystallizes in the triclinic space group P-1, Z=2 with a=10.284(2)A, b=10.790(2)A, c=11.305(2)A, alpha=64.92(3) degrees , beta=89.88(3) degrees , gamma=62.99(3) degrees , V=983.7(3)A(3) and D(calc)=1.339Mg/m(3). The molecular structure, vibrational frequencies and infrared intensities of PANT were calculated by the Hartree-Fock and density functional theory methods (BLYP and B3LYP) using the 6-31G* basis set. The calculated geometric parameters were compared to the corresponding X-ray structure of the title compound. We obtained 22 stable conformers for the title compound; however Conformer 1 is approximately 9.53kcal/mol more stable than Conformer 22. The comparison of the theoretical and experimental geometry of the title compound shows that the X-ray parameters fairly well reproduce the geometry of Conformer 17. The harmonic vibrations computed for this compound by the B3LYP/6-31G* method are in good agreement with the observed IR spectral data. Theoretical vibrational spectra of the title compound were interpreted by means of PEDs using the VEDA 4 program. A general better performance of the investigated methods was calculated by PAVF 1.0 program.

The Molecular Structure and Vibrational Spectrum of 6-bromo-8-thia-1,4-epoxybicyclo[4.3.0]non-2-ene

Geometric parameters and FT-IR spectrum of 6-bromo-8-thia-1,4-epoxybicyclo[4.3.0]non-2-ene were computed by the HF, B3LYP, B3PW91 and mPW1PW91 methods in conjunction with the 6-31G(d,p) basis set. The calculated IR spectra are in a good agreement with the observed FT-IR spectrum. A general better performance of B3LYP, B3PW91 and mPW1PW91 versus HF was quantitatively characterized by using PAVF 1.0 program. Optimal uniform scaling factors calculated for the title compound are 0.8952, 0.9552, 0.9520 and 0.9456 for HF, B3LYP, B3PW91 and MPW1PW91 methods, respectively.