Quantum Mechanical Force Field Research Articles

Spectroscopic, Vibrational and Topology Analysis of (2R, 3R) - Butanediol bis (Methanesulfonate)

Objectives: To find the (2R, 3R)-Butanediol bis (methanesulfonate) (BBM) to be the most bioactive through DFT calculations and multi-spectroscopic investigations. Methods: BBM molecule was characterized by multi-spectroscopic investigations (FT-IR, FT-Raman, UV-Vis) and quantum chemical computations employing density functional theory with wB97XD and cam-B3LYP basis functional. Findings: The assignments of vibrational spectral features were made with the help of Gar2ped, which incorporates the Scaled Quantum Mechanical Force Field (SQMFF) methodology. The absolute energy gap between the frontier molecular orbitals (HOMO and LUMO) at room temperature and reactivity descriptors confirm that the molecule BBM is chemically active, to realize the charge transfer within the molecule and shows the best bioactive molecule. Moreover, the weak intramolecular interaction and evaluate the intermolecular interaction (hydrogen bonds) were revealed from quantum topological atoms in molecules and reduced density gradient plots. Novelty: BBM molecule was found to very good bioactive molecules, given the results of vibrational, topological, quantum computational methods and RDG analysis. Keywords: BBM; DNA; SQMFF; HOMO; LUMO

Structural and vibrational investigation of Cis-Trans isomers of potent insecticide allethrin.

In this research, the optimised structural and vibrational properties of cis-trans isomers of powerful insecticide allethrin were theoretically studied in gas phase and in aqueous and ethanol solutions by using hybrid B3LYP/6-311 + + g(d,p) level of theory. The results revealed that the permittivity of solvent has influence on the properties of both isomers, thus, higher dipole moments and solvation energies are observed in water, a solvent of higher permittivity (78.355) than ethanol. Complete vibrational assignments of both isomers were done by combining the experimental IR spectrum of allethrin with the scaled quantum mechanical force field (SQMFF) methodology and the determination of corresponding scaled force constants in gas phase and aqueous solution are reported. Different signs of dihedral O2C10C6C4 angles of both isomers (negative in cis and positive in trans) support the differences in the vibrational assignments. Natural bond orbital (NBO) calculations suggest that both isomers are highly stable in gas phase and aqueous solution and that the side chains and five member's rings are involved in the n → σ* interactions. However, atoms in molecules (AIM) studies reveal a higher stability of form cis in both media than the trans one. Merz-Kollman (MK), Mulliken and natural population atomic (NPA) charges for both isomers support the higher hydration of trans isomer in aqueous media and, hence, the higher solvation energy in water (ΔGC/ZPVE = - 80.29kJ/mol). Changes in the bond orders of O and C atoms of side chain are observed in water as a consequence of hydration. The higher stability of the cis form in the above solutions could be explained by the lower solvation energy in water, as supported by AIM calculations. The studies of frontier orbital reveal that the cis form in both media is sligthly more reactive than the trans form.

Hydrogen bonding interaction and topological insights of the electron localization/delocalization of l- arginine acetate

The vibrational spectral studies of the semi-organic material l- arginine acetate (LAA) are carried out with the help of density functional calculations to derive the equilibrium geometry as well as the vibrational wavenumbers and intensities of the spectral bands. The vibrational spectrum assignments are performed using normal coordinate analysis (NCA) in accordance with the scaled quantum mechanical force field approach (SQMFF). Vibrational spectra confirm the COO- modes split due to intra- and intermolecular association based on C–O….H, N–H….O, and O–H⋯O hydrogen bonding in the molecule, which lowers carboxylate wavenumbers. The natural bond orbital (NBO) analysis and DFT computations also confirm the occurrence of strong intra and intermolecular N–H⋯O and O–H⋯O ionic hydrogen bonding between charged species, providing the non-centrosymmetric structure in the LAA crystal.

Vibrational Study of Mono and Diprotonated Species of Potent Anti-acid Ranitidine Hydrochloride Combining DFT with SQMFF Calculations

Structural and vibrational studies of mono (M) and diprotonated (D) species of ranitidine hydrochloride (RH) have been performed by combining B3LYP/6-31G* calculations with the scaled quantum mechanical force field (SQMFF) methodology. Four M structures in the gas phase and aqueous solution and two D E/Z and Z/E isomers in solution were considered. The M and D free base, cationic, and hydrochloride species show higher dipole moment values and expansion of volumes in solution, while higher solvation energies are predicted for both D (E/Z) and (Z/E) species. NBO and AIM studies suggest high stabilities of D (Z/E) cationic and hydrochloride species in solution. Gap values show that the M and D species are the most reactive in both media. M and two D forms were completely assigned, and their force constants were reported. The D hydrochloride (E/Z) form shows two IR bands at 2718 and 2625 cm-1 assigned to νN6-H34 and νN5-H44 stretching modes where the formation of O3-H34···N6 bond justifies the strong shifting of N6-H34 stretching mode towards lower wavenumbers. The IR bands at 2563, 2515, and 2475 cm-1 assigned to the two D species, together with the absence of an intense band at 1764 cm-1, show clearly that M species is not present in the solid phase, but the two D hydrochloride (E/Z) and (Z/E) species.

Scaled in Cartesian Coordinates Ab Initio Molecular Force Fields of DNA Bases: Application to Canonical Pairs.

The model of Regularized Quantum Mechanical Force Field (RQMFF) was applied to the joint treatment of ab initio and experimental vibrational data of the four primary nucleobases using a new algorithm based on the scaling procedure in Cartesian coordinates. The matrix of scaling factors in Cartesian coordinates for the considered molecules includes diagonal elements for all atoms of the molecule and off-diagonal elements for bonded atoms and for some non-bonded atoms (1–3 and some 1–4 interactions). The choice of the model is based on the results of the second-order perturbation analysis of the Fock matrix for uncoupled interactions using the Natural Bond Orbital (NBO) analysis. The scaling factors obtained within this model as a result of solving the inverse problem (regularized Cartesian scale factors) of adenine, cytosine, guanine, and thymine molecules were used to correct the Hessians of the canonical base pairs: adenine–thymine and cytosine–guanine. The proposed procedure is based on the block structure of the scaling matrix for molecular entities with non-covalent interactions, as in the case of DNA base pairs. It allows avoiding introducing internal coordinates (or coordinates of symmetry, local symmetry, etc.) when scaling the force field of a compound of a complex structure with non-covalent H-bonds.

Structural study and vibrational assignments of FT-IR and FT-Raman spectra of powerful pesticide 2,4’-DDT. Its comparison with 4,4’-DDT

In this work, the S(+) and R(-) forms of powerful pesticide 2,4’-DDT have been experimentally characterized by using the experimental FT-IR and FT-Raman spectra in the solid phase accomplished with calculations derived from the density functional theory (DFT) together with the 6-31G* and 6-311++G** basis sets. The optimizations in gas phase with both levels of calculations reveal that the R(-) form is the most stable of 2,4’-DDT, as was experimentally observed in the solid state. Here, the geometrical parameters, atomic charges, bond orders, main delocalization energies, the topological parameters, force constants and the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gaps for both forms of 2,4’-DDT were compared with reported for R-4,4’-DDT. Complete assignments of 78 vibration normal modes for R-2,4’-DDT were performed by using the scaled quantum mechanical force field (SQMFF). Comparisons between both DDT derivatives show that the structural change of one Cl atom in para position in 4,4’-DDT to ortho position in R-2,4’-DDT produce changes in the assignments, intensities and positions of IR bands between 1400 and 1200 cm−1 region while a set of bands in the region close to 1000 cm−1 are only observed in the Raman spectra of R-2,4’-DDT. The vibration CCl3 and C-Cl modes of groups or bonds common to the two DDT species are predicted in practically the same positions. Natural bond orbital (NBO) and atoms in molecules (AIM) calculations evidence higher stability of form R-2,4’-DDT as compared with the S one while the gap values support lower reactivities of both forms of 2,4’-DDT as compared with 4,4’-DDT. Finally, the scaled force constants related to diphenyl rings and trichloroethane groups of both derivatives present practically the same values.

Experimental and DFT studies on structure, spectroscopic and thermal properties of N-Methyl-N,N,N-trioctylammonium chloride ionic liquid

The [Aliquat+][Cl−] ionic liquid (IL) has been structural and vibrationally characterized combining experimental FT-IR, FT-Raman and 1H- and 13C-NMR spectroscopies with theoretical studies based on the hybrid B3LYP/6-31G* method. The theoretical determination of structure of IL in gas phase and aqueous solution by using that level of theory shows three ionic C-H···Cl bonds, as supported by atomic Merz-Kollman (MK) charges, bond orders, natural bond orbital (NBO) and atoms in molecules (AIM) calculations. Hence, a monodentate coordination between the [Aliquat+] cation and Cl anion has been proposed for IL because only one of three ionic C-H···Cl bonds presents higher energy and lower distance. The optimized structure confirmed by NMR measurements has allowed the assignments of 237 normal vibration modes to the bands observed in the infrared and Raman spectra with the aid of scaled quantum mechanical force field (SQMFF) methodology and the normal internal coordinates. The effect of Cl in the IL is the shifting of vibration modes corresponding to the CH2 and CH3 groups, as compared with the cation. The mapped MEP surface evidence a strong concentration of charges around the chloride anion compatible with nucleophilic sites in these regions while the frontier orbital analyses suggest that IL is most reactive than the cation probably due to the low values of both global electrophilicity and nucleophilicity indexes. The thermal stability shows that [Aliquat+][Cl−] start to decompose just above 200°C. Comparisons between [Aliquat+][Cl−] and [Aliquat+][NTf2−] ILs show that the IL containing chloride is most reactive than the other one while [Aliquat+] [NTf2−] is thermally more stable than [Aliquat+][Cl−]. These results suggest that the properties of an IL containing the [Aliquat+] cation are strongly dependent of anion. In addition, the scaled force constants for the [Aliquat+][Cl−] IL are also calculated and compared with the reported for the cation. The Cl anion modifies in notable form the properties of cation.

Structural Study and Vibrational Assignments of Anticonvulsant Topiramate by using DFT calculations and Two Harmonic Force Fields

B3LYP/6-311++G** calculations have been combined with the scaled quantum mechanical force field (SQMFF) methodology to study structural and vibrational properties of anticonvulsant topiramate (TPM) agent. The 123 vibration modes expected for TPM were completely assigned, considering two harmonic force fields. In one case, C2V symmetries were considered for both SO2 and NH2 groups, while in the other one C2V and C3V symmetries for the NH2 and SO3 groups, respectively. The calculated harmonic vibrational frequencies are consistent with the experimental IR and Raman spectra in the solid phase. Very good concordances were found between the theoretical structures in gas phase and aqueous solution and the corresponding experimental reported. Thus, the fused five-membered ring in TPM produces that the pyranose ring adopts distorted twist-boat conformation, as was experimentally observed. In solution, all calculations were performed with the self-consistent reaction force (SCRF) method by the integral equation formalism variant polarised continuum (IEFPCM) and universal solvation model density (SMD) models. The corrected solvation energy value for TPM in aqueous solution by total non-electrostatic terms and by ZPVE is -1066.10 kJ/mol. The bond orders have evidenced that the three O atoms are not linked of the same form to S atom. Hence, the S atom of TPM is practically tetra-coordinate in both media, as evidenced by the high negative MK and NPA charges on the O atoms linked to it. The AIM study supports the higher stability of TPM in the gas phase while the NBO calculations suggest higher stability in solution. Gap values support the higher reactivity of TPM in solution than in the gas phase. The scaled force constant for both cases are reported for the first time. Comparisons of predicted 1H- and 13C-NMR spectra with the corresponding experimental ones reveal very good concordances.

Stable numerical methods for determination of the molecular clusters force fields

Abstract The inverse problem of molecular force fields calculation is considered within the theory of regularization. In our strategy, we choose the stabilizing matrix F 0 F^{0} as a result of quantum mechanical calculations. The solution of the inverse problem is finding a matrix 𝐹 which is the nearest by the chosen Euclidean norm to the given ab initio F 0 F^{0} . The optimized solution is referred to as regularized quantum mechanical force field (RQMFF). Regularizing algorithms of molecular force fields calculation based on the joint treatment of experimental and ab initio quantum mechanical data have been applied to the calculations of molecular force fields (matrices of force constants) for small water clusters (H2O)𝑛 ( n = 2 , 3 n=2,3 ).

Molecular structure, electronic properties and drug-likeness of xylazine by quantum methods and qsar analysis

Xylazine is an adrenergic alpha-2 agonist used as a sedative, analgesic and centrally acting muscle relaxant in veterinary medicine. In this study, the anaesthetic compound Xylazine was optimized in the electronic ground state using Density Functional Theory at B3LYP/6–311 + G (d, p) level. This study aims at revealing the various electro physical and chemical properties of Xylazine. This study will be useful for future research on the title compound. The stabilization energies and the electronic transitions were achieved with the aid of Natural Bond Orbital (NBO) analysis. The vibrational pattern of the molecule was characterized by FT-IR and FT-Raman spectra using Scaled Quantum Mechanical Force Field calculations. The presence of strong hydrogen bonding interactions was evidently revealed by the shifting of wavenumbers. NBO analysis reveals the stability of the molecule. Further, the strength of association between adrenergic receptor and Xylazine was predicted using a computer-based analysis of molecular modeling interaction techniques. A detailed molecular picture of this anesthetic compound and its interactions were obtained by modeling analysis, NBO analysis, IR, Raman and UV–Vis spectroscopy.

Growth, Z-scan and density functional theoretical study for investigating the nonlinear optical properties of guanidinium l-glutamate for optical limiting applications

A novel semi-organic single-crystal exhibiting third order optical nonlinearity was grown by the method of slow evaporation. Single crystal X-ray diffraction technique (XRD) was employed to confirm the crystal structure and powder XRD was used to determine the cell parameters. The sample was characterized using FT-IR, FT-Raman and UV–visible absorption and analysed with density functional theory (DFT) calculations. The detailed interpretation of the vibrational spectra has been carried out using normal coordinate analysis (NCA) through the scaled quantum mechanical force field methodology. The red shifting of NH stretching wavenumbers, both the observed and calculated, affirm that NH......O type bonds are present in GuLG. The Natural Bond Orbital (NBO) analysis also points to a strong intermolecular NH....O hydrogen bond. Thermal stability of the crystal was studied making use of the TG/DTA technique. The third-order nonlinearity studies, along with the optical limiting behaviour were investigated by Z-scan technique using diode-pumped Nd: YAG laser with 50 mW power at 532 nm.H

Vibrational Studies of Species Derived from Potent S(+) and R(-) Ecstasy Stimulant by Using Ab-initio Calculations and the SQM Approach

B3LYP/6-311++G** calculations and the scaled quantum mechanical force field (SQMFF) approach have been used to study the structures and vibrational spectra of three species derived from potent S(+) and R(-) ecstasy stimulant. The complete vibrational assignments of free base, cationic, and hydrochloride species of both enantiomeric forms of ecstasy have been reported by using the normal internal coordinates and the experimental available attenuated total reflectance ATR-IR and FT-Raman spectra. SQM calculations predicted that the three species could be present in the IR spectrum of hydrochloride species because the IR bands of medium intensity at 2794 cm-1 is assigned to the stretching C4-H15 and symmetric CH3 modes of the free base while the strong IR band at 1508 cm-1 is assigned easily to NH2 stretching mode of hydrochloride species and NH2 deformation modes of cationic species. The calculations reveal the same energy values for both enantiomers, indicating that both could exist simultaneously in the two media with similar corrected solvation energies in solution probably because the R(-) form is quickly converted to the S(+) one. Three types of charges studied in both media evidence higher effect on the N atoms belonging to N-CH3 groups of three species of S(+) form of ecstasy in both media than on the O atoms of R1 ring. The high gap value predicted for the hydrochloride species of S(+) form in solution supports the low reactivity of this species, in agreement to its higher stability evidenced in this medium by AIM and NBO calculations. The predicted Ultraviolet-visible and Electronic Circular Dichroism ecstasy (ECD) support the presence of both enantiomeric forms in solution while excellent concordance evidence the comparisons between the predicted 1H- and 13C-NMR chemical shifts for the three species of S(+) form of ecstasy with the corresponding experimental ones.

Bidentate cation-anion coordination in the ionic liquid 1-ethyl-3-methylimidazolium hexafluorophosphate supported by vibrational spectra and NBO, AIM and SQMFF calculations

Experimental attenuated total reflectance (ATR) and Raman spectra for the synthesized ionic liquid 1-Ethyl-3-methylimidazolium hexafluorophosphate [EMIM+][PF6−] have been combined with the functional hybrid B3LYP and the 6-31G∗ and 6-311++G∗∗ basis sets in order to evaluate the coordination mode of [PF6−] anion and determine the its structural, electronic, topological and vibrational properties. The scaled quantum mechanical force fields (SQMFF) methodology allowed us to obtain a set of scaled force constants fitting the observed wavenumbers because, so far, they have not reported. Experimental ATR and Raman spectra for the ionic liquid [EMIM+][PF6−] in the solid phase are consistent with the corresponding predicted by using both levels of theory. Here, complete vibrational assignments of 72 normal modes of vibration expected for ionic liquid were performed by using B3LYP/6-311++G∗∗ level and considering that the [PF6−] anion adopts a bidentate coordination mode. Atomic Merz-Kollman (MK) charges and bond orders studies have revealed a distorted octahedral symmetry of anion in the ionic liquid and have suggested bidentate coordination of anion by two C–H⋯F hydrogen bonds, as experimentally was also proposed. Natural bond orbital (NBO) and atoms in molecules (AIM) calculations support the high stability of ionic liquid and its high dipole moment value. Frontier orbitals for the three species show that the [PF6−] anion increases the reactivity of ionic liquid. Here, we determine that the B3LYP/6-311++G∗∗ molecular force field for the ionic liquid [EMIM+][PF6−] with the bidentate coordination mode adopted by [PF6−] anion is well represented, as also was supported by the scaled force constants calculated for both C–H⋯F hydrogen bonds.

A combined experimental and theoretical study on vibrational spectra of 3-pyridyl methyl ketone

Using some spectral methods and density functional theory calculations, a complete structural, vibrational, thermodynamic, electronic, nonlinear optical properties of 3-pyridyl methyl ketone have been evaluated. The Fourier transform infrared spectrum was obtained for the title molecule at room temperature. In the theoretical calculations, the Becke three Lee-Yang-Parr functional with 6-311++G(d,p) basis set was applied to carry out the quantum mechanical calculations. The infrared spectra were interpreted by using of normal coordinate analysis based on the scaled quantum mechanical force field. In addition, molecular electrostatic potential map, some thermodynamic parameters at different temperatures of compound were investigated.

USING MOLECULAR ELECTROSTATIC POTENTIALS AND FRONTIER ORBITALS FOR THE SURFACE-ENHANCED RAMAN INTERPRETATION OF FLUOXETINE

Raman and surface-enhanced Raman (SERS) spectra of (N-methyl-3-phenyl-3-[4-(trifluoromethyl)phenoxy)propane-1-amine hydrochloride, fluoxetine, have been recorded. Density functional theory with the B3LYP functional was used for optimization of the ground state geometry, calculation of the Raman normal modes of this molecule and the modelling of the SERS effect. Calculated geometrical parameters of fluoxetine fit well with the experimental ones. Based on the recorded data, the DFT results and a normal coordinate analysis based on a scaled quantum mechanical (SQM) force field approach, a complete vibrational assignment of fluoxetine as well as its adsorption behavior on a silver surface (using SERS selection rules) is derived.

Intricate spectroscopic profiling, light harvesting studies and other quantum mechanical properties of 3-phenyl-5-isooxazolone using experimental and computational strategies

This manuscript presents the detailed experimental and computational structural, physical property study of 3-phenyl-5-isooxazolone (3P5I). Different experimental spectral studies like IR, UV, Raman and NMR were used to get an insight on the actual structure of the compound. |It was followed by computational simulation of the structure using DFT approach employing B3LYP functional and 6-311++G (d, p) basis set. Scaled quantum mechanical force field method (SQMFF)was used to assign different vibrations in the spectra using normal coordinate analysis (NCA) and found that close agreement with investigational values. Experimental NMR(1H and 13C NMR) spectrum was also compared with the theoretically simulated spectra using GIAO-gauge independent atomic orbital formalism. UV–Vis Spectrum of compound also studied extensively using theoretical and experimental techniques. Most importantly, the compound shows high light harvesting efficiency hence can be used like a very good photosensitiser in DSSC (dye sensitized solar cells). The overall efficiency of the cell is more than 8% in a titanium dioxide based cell, which is high when compared to similar cells. MEP surfaces, HOMO-LUMO, NLO properties, chemical reactivity descriptors, NBO analysis, and Mulliken atomic charge analysis were also executed to predict physical as well as chemical properties. Molecular docking simulations show that the compounds can be used as effective apoptosis agonist and antiasthmatic agent.

Charge transfer interaction and vibrational spectral investigation of 2-amino-5-nitropyridinium sulfamate

A hetero aromatic nonlinear optical crystal, 2-amino-5-nitropyridinium sulfamate was synthesized by slow evaporation method. An optimized molecular structure and theoretical vibrational spectra were obtained and analyzed by use of density functional theory. The observed vibrational wavenumbers in the experimental spectra were compared with the calculated results. Scaled quantum mechanical force field methodology with normal coordinate analysis was used for the assignment of experimental infrared and Raman spectra. The second harmonic generation and photoluminescence properties of the crystal were studied. The charge transfer interaction between the donor acceptor moieties were obtained by means of natural bond orbital analysis.

Development and Validation of the Quantum Mechanical Bespoke Protein Force Field.

Molecular mechanics force field parameters for macromolecules, such as proteins, are traditionally fit to reproduce experimental properties of small molecules, and thus, they neglect system-specific polarization. In this paper, we introduce a complete protein force field that is designed to be compatible with the quantum mechanical bespoke (QUBE) force field by deriving nonbonded parameters directly from the electron density of the specific protein under study. The main backbone and sidechain protein torsional parameters are rederived in this work by fitting to quantum mechanical dihedral scans for compatibility with QUBE nonbonded parameters. Software is provided for the preparation of QUBE input files. The accuracy of the new force field, and the derived torsional parameters, is tested by comparing the conformational preferences of a range of peptides and proteins with experimental measurements. Accurate backbone and sidechain conformations are obtained in molecular dynamics simulations of dipeptides, with NMR J coupling errors comparable to the widely used OPLS force field. In simulations of five folded proteins, the secondary structure is generally retained, and the NMR J coupling errors are similar to standard transferable force fields, although some loss of the experimental structure is observed in certain regions of the proteins. With several avenues for further development, the use of system-specific nonbonded force field parameters is a promising approach for next-generation simulations of biological molecules.

Structural and SQMFF study of potent insecticide 4′,4′-DDT combining the FT-IR and FT-Raman spectra with DFT calculations

The experimental FT-IR and FT-Raman spectra in the solid state have been employed to vibrationally characterize the potent insecticide dichlorodiphenyltrichloroethane (4′,4′-DDT). The complete vibrational assignments of 4′,4′-DDT in gas phase and in acetone and diethyl-ether were performed combining hybrid B3LYP/6-31G* and B3LYP/6–311++G** calculations with the internal coordinates, the scaled quantum mechanical force field (SQMFF) methodology and the experimental spectra. Here, the molecular structures of 4′,4′-DDT were theoretically determined in gas phase and in acetone and diethyl-ether solutions by using those two methods. The self-consistent reaction field (SCRF) method and the integral equation formalism variant polarised continuum model (IEFPCM) model were employed to study the properties in solution while the solvation energies were predicted by using the solvation model. The B3LYP/6–311++G** calculations show higher solvation energy in the solvent with lower permittivity, diethyl-ether. A clear and direct correlation was found with both basis sets between solvation energy and dipole moment for those two solvents. NBO studies clearly show that dichlorodiphenyl groups confer to 4,4′-DDT higher stability than the trichloroethyl group due to the fact that the lone pairs of Cl21 and Cl22 atoms present the n→π* transitions while the AIM study shows the participation of trichloroethyl group in halogen bonds clearly justifying the stability of 4′,4′-DDT in the three media and with both basis sets. The MK and NPA charges evidence different behaviors in both media and with both basis sets. The frontier orbitals show that the reactivity of 4,4′-DDT strongly depends on the basis set while it is more reactive than dieldrin, hexachlorobenzene and saxitoxin but 3,3′,4,4′-tetrachloroazobenzene, 3,3′,4,4′ tetrachloroazoxybenzene, CN− and CO species present higher reactivity than 4,4′-DDT. The number of Cl atoms could justify the differences observed in the nucleophilicity indexes of 4,4′-DDT, dieldrin, hexachlorobenzene, 3,3′,4,4′-tetrachloroazobenzene and 3,3′,4,4′ tetrachloroazoxybenzene.

Combined Vibrational Spectroscopic and Quantum Chemical Investigations of 1,8-diaminooctane

This paper contains the molecular parameters, vibrational properties and some theoretical calculations of 1,8-diaminooctane. Bond angles, bond lengths, vibrational properties, dipole moments, frontier molecular orbitals and molecular electrostatic potential of 1,8-diaminooctane were performed with using density functional theory calculations with B3LYP/6-311++G(d,p) level of theory. Vibrational properties were interpreted with the by using scaled quantum mechanical force field. This study enables us to figure out the vibrational and structural properties and some electronic properties of the 1,8-diaminooctane by means of the theoretical and experimental studied methods.