Vibrational spectra of partially oriented molecules having two conformers in nematic and isotropic solutions: furfural and 2-chlorobenzaldehyde

A fluorescence-enhanced method specific for furfural determination in Chinese Baijiu based on luminescent carbon dots and direct surface reaction

Detecting the furfural concentration in Baijiu can be used to assess the quality of Baijiu, allowing for the optimization of processing techniques and the enhancement of overall quality. In this paper, a fluorescence-enhanced method based on carbon dots (o-CDs) is developed for the furfural determination in Chinese Baijiu. In an environment full-filled with ·SO4- and ·OH, furfural undergone a direct surface reaction with the ortho-diamino groups at o-CDs. The created furan-based imidazole increased the surface electron density, leading an emission enhancement and color changes from orange to green. Thereby, a linear fluorescence response of o-CDs-TA to furfural is established in water with a detection limit of 30.5 nM. Finally, after ethanol correction it is used to determine furfural in Chinese Baijiu with high precision and reproducibility, providing a new strategy with low-cost and high sensitivity. In particular, the idea of covalently connecting target molecule to the CDs surface via the assistance of free radical opens a new avenue to merge the nanoscale and molecular realms through implementing chemical role into carbon nanostructures.

Correlating the Valence State with the Adsorption Behavior of a Cu-Based Electrocatalyst for Furfural Oxidation with Anodic Hydrogen Production Reaction

The low-potential furfural oxidation reaction (FFOR) on a Cu-based electrocatalyst can produce H2 at the anode, thereby providing a bipolar H2 production system with an ultralow cell voltage. However, the intrinsic activity and stability of the Cu-based electrocatalyst for the FFOR remain unsatisfactory for practical applications. This study investigates the correlation between the valence state and the adsorption behavior of the Cu-based electrocatalyst in furfural oxidation. Cu0 is the adsorption site with low intrinsic activity. Cu+ , which exists in the form of Cu(OH)ads in alkaline electrolytes, has no adsorption ability but can improve the performance of Cu0 by promoting the adsorption of FF. Moreover, a mixed-valence Cu-based electrocatalyst (MV Cu) with high intrinsic activity and stability is prepared electrochemically. With the MV Cu catalyst, the assembled dual-side H2 production electrolyzer has a low electricity requirement of only 0.24 kWh mH2 -3 at an ultralow cell voltage of 0.3 V, and it exhibits sufficient stability. This study not only correlates the valence state with the adsorption behavior of the Cu-based electrocatalyst for the low-potential FFOR with anodic H2 production but also reveals the mechanism of deactivation to provide design principles for Cu-based electrocatalysts with satisfactory stability.

Insight into the Interaction of Furfural with Metallic Surfaces in the Electrochemical Hydrogenation Process

Electrocatalytic hydrogenation of furfural on metal surfaces has become an important research subject due to the potential of the reaction product 2-methylfuran as a renewable energy resource. Identifying effective determinants in this reaction process requires a thorough investigation of the complex electrode-electrolyte interactions, which considers a variety of the influential components. In this work, in operando electrochemical Raman Spectroscopy and Molecular Dynamics simulations were utilized to investigate different characteristics of the interface layer in the electrocatalytic hydrogenation of furfural. Hereby, the influence of applied potentials, electrode material, and electrolyte composition were investigated in detail. The studied parameters give an insight into furfural's binding situation, molecular orientation, and reaction mechanism.

Kinetic and structural understanding of bulk and supported vanadium-based catalysts for furfural oxidation to maleic anhydride

The kinetics of gas-phase furfural partial oxidation to maleic anhydride (MA) was studied over bulk vanadium–phosphorus-based catalysts obtained by aqueous (VPAq) and organic (VPOr) methods and compared to a supported V2O5/Al2O3 catalyst.

Infrared spectroscopic measurements of the structure of organic thin films; furfural on Pd(111) and Au(111) surfaces

This work demonstrates the use of reflection–adsorption infrared spectroscopy for continually monitoring the structure of organic thin films as a function of thickness and temperature to complement diffraction methods.

Electrochemical biomass valorization on gold-metal oxide nanoscale heterojunctions enables investigation of both catalyst and reaction dynamics with operando surface-enhanced Raman spectroscopy

The electrochemical oxidation of biomass platforms such as 5-hydroxymethylfurfural (HMF) to value-added chemicals is an emerging clean energy technology.

The electrochemical oxidation of biomass platforms such as 5-hydroxymethylfurfural (HMF) to value-added chemicals is an emerging clean energy technology. However, mechanistic knowledge of this reaction in an electrochemical context is still lacking and operando studies are even more rare. In this work, we utilize core–shell gold-metal oxide nanostructures which enable operando surface-enhanced Raman spectroelectrochemical studies to simultaneously visualize catalyst material transformation and surface reaction intermediates under an applied voltage. As a case study, we show how the transformation of NiOOH from ∼1–2 nm amorphous Ni layers facilitates the onset of HMF oxidation to 2,5-furandicarboxylic acid (FDCA), which is attained with 99% faradaic efficiency in 1 M KOH. In contrast to the case in 1 M KOH, NiOOH formation is suppressed, and consequently HMF oxidation is sluggish in 10 mM KOH, even at highly oxidizing potentials. Operando Raman experiments elucidate how surface adsorption and interaction dictates product selectivity and how the surface intermediates evolve with applied potential. We further extend our methodology to investigate NiFe, Co, Fe, and CoFe catalysts and demonstrate that high water oxidation activity is not necessarily correlated with excellent HMF oxidation performance and highlight catalytic factors important for this reaction such as reactant–surface interactions and the catalysts' physical and electronic structure. The insights extracted are expected to pave the way for a deepened understanding of a wide array of electrochemical systems such as for organic transformations and CO₂ fixation.

Tandem Hydrogenation/Hydrogenolysis of Furfural to 2-Methylfuran over a Fe/Mg/O Catalyst: Structure–Activity Relationship

The hydrodeoxygenation of furfural (FU) was investigated over Fe-containing MgO catalysts, on a continuous gas flow reactor, using methanol as a hydrogen donor. Catalysts were prepared either by coprecipitation or impregnation methods, with different Fe/Mg atomic ratios. The main product was 2-methylfuran (MFU), an important highly added value chemical, up to 92% selectivity. The catalyst design helped our understanding of the impact of acid/base properties and the nature of iron species in terms of catalytic performance. In particular, the addition of iron on the surface of the basic oxide led to (i) the increase of Lewis acid sites, (ii) the increase of the dehydrogenation capacity of the presented catalytic system, and (iii) to the significant enhancement of the FU conversion to MFU. FTIR studies, using methanol as the chosen probe molecule, indicated that, at the low temperature regime, the process follows the typical hydrogen transfer reduction, but at the high temperature regime, methanol dehydrogenation and methanol disproportionation were both presented, whereas iron oxide promoted methanol transfer. FTIR studies were performed using furfural and furfuryl alcohol as probe molecules. These studies indicated that furfuryl alcohol activation is the rate-determining step for methyl furan formation. Our experimental results clearly demonstrate that the nature of iron oxide is critical in the efficient hydrodeoxygenation of furfural to methyl furan and provides insights toward the rational design of catalysts toward C–O bonds’ hydrodeoxygenation in the production of fuel components.

W(OTf)6 -Catalyzed Synthesis of γ-Lactones by Ring Contraction of Macrolides or Ring Closing of Terminal Hydroxyfatty Acids in Ionic Liquid

γ-Lactones are an important class of fine chemical products and are widely used in perfumes, medicines, pesticides, dyes, and other fields. Herein, a new method for γ-lactones preparation based on ring contraction was developed. Starting from macrolides, W(OTf)₆ was used to catalyze the ring-opening polymerization then depolymerization. The depolymerization step was not a common ring-closing process, and the carbon number of the ring was reduced one by one by rearrangement to form the most thermodynamically stable five-membered ring compounds. γ-Caprolactone (180 °C for 10 h) was obtained in a yield of 94 % when [EMIM]OTf was used as the solvent, and the yield of isolated product was up to 85 %. The interaction of various components and the reaction mechanism were studied by FTIR spectroscopy and ¹ H NMR spectroscopy, respectively. Furthermore, γ-lactones could be produced when the substrate was extended to terminal hydroxyfatty acids. Unexpectedly, the catalyst was poisoned by 1 equivalent of H₂ O added during the process and thus the yield decreased greatly. The reaction is green and simple, and proceeds in one pot with high atom economy (100 % for macrolides and with water as the only byproduct for terminal hydroxyfatty acid), which provides a promising approach to synthesizing γ-lactones.

Excitation of vibrational quanta in furfural by intermediate-energy electrons

We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°-90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule.

Spectroscopic (FT-IR, FT-Raman and UV) investigation, NLO, NBO, molecular orbital and MESP analysis of 2-{2-[(2,6-dichlorophenyl)amino]phenyl}acetic acid

In this work, FT-IR and FT-Raman spectra of 2-{2-[(2,6-dichlorophenyl)amino]phenyl}acetic acid (abbreviated as 2DCPAPAA) have been reported in the regions 4000-450cm(-1) and 4000-50cm(-1), respectively. The molecular structure, geometry optimization, intensities, vibrational frequencies were obtained by the ab initio and DFT levels of theory B3LYP with 6-311++G(d,p) standard basis set and a different scaling of the calculated wave numbers. The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes calculated using vibrational energy distribution analysis (VEDA 4) program. The harmonic frequencies were calculated and the scaled values were compared with experimental FT-IR and FT-Raman data. The observed and the calculated frequencies are found to be in good agreement. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The thermodynamic properties of the title compound at different temperature reveal the correlations between standard heat capacities (C) standard entropies (S) standard enthalpy changes (ΔH). The important non-linear optical properties such as electric dipole momentum, polarizability and first hyperpolarizability of 2DCPAPAA have been computed using B3LYP/6-311++G(d,p) quantum chemical calculations. The Natural charges, HOMO, LUMO, chemical hardness (η), chemical potential (μ), Electro negativity (χ) and electrophilicity values (ω) are calculated and reported. The oscillator's strength, wave length, and energy calculated by TD-DFT and 2DCPAPAA is approach complement with the experimental findings. The molecular electrostatic potential (MESP) surfaces of the molecule were constructed.

The effects of electronegative substituent atoms on structural, vibrational, electronic and NLO properties of some 4-nitrostilbene derivates

Organic compounds which have one or more aromatic systems in conjugated positions show charge transfer interactions which are responsible for the non-linear properties of the compounds. A conjugated π electron system enables a pathway for the entire length of conjugation under the perturbation of an external electric field. When electron donating and withdrawing moieties are located at terminal position of conjugated backbone, nonlinear optical (NLO) properties have been increased significantly which involve the correlated and high delocalized π electron states. Recently synthesized organic complexes, 1-(4-fluorostyryl)-4-nitrostilbene (1), 4-Chloro 4-nitrostilbene (2), 4-Bromo 4-nitrostilbene (3) and 4-Iodo 4-nitrostilbene (4), were simulated using density functional theory (DFT). Based on the optimized geometries, spectroscopic and NLO properties of these complexes were discussed as compared with each other.

Quantum chemical computations, vibrational spectroscopic studies, NLO and NBO/NLMO analysis of o-chlorobenzohydrazide

The molecular vibrations of o-chlorobenzohydrazide (OCBH) have been investigated in polycrystalline sample, at room temperature, by recording Fourier transform infrared (FT-IR) and FT-Raman spectroscopies. The complete vibrational assignment and analysis of the fundamental modes was carried out using the experimental data and quantum chemical studies. The observed vibrational data were compared with the wavenumbers derived theoretically for the optimized geometry of the compound from the HF and DFT/B3LYP calculations employing 6-311++G(d,p) basis set. The (1)H and (13)C NMR chemical shifts have been simulated. Thermodynamic properties have been calculated at different temperatures. HOMO-LUMO energy gap has been calculated. The intramolecular contacts have been interpreted using Natural Bond Orbital (NBO) and Natural Localized Molecular Orbital (NLMO) analysis.

Molecular structure, vibrational investigation of 2-chloro-α-α-α-trifluoro-3,5-dinitrotoluene using DFT (LSDA, B3LYP, B3PW91 and MPW1PW91) and UV-Vis absorption spectra in organic solvents: a IEF-PCM/TD-DFT study

Theoretical Spectrograms (IR and Raman) have been constructed and compared with the experimental FT-IR and FT-Raman spectra. The effect of solvent polarity on the optimized structure is studied by the density functional theory calculation (LSDA, B3LYP, B3PW91 and MPW1PW91 with 6-311++G(d,p)) in gas phase and selected solvents benzene (non-polar solvent), tetrahydrofuran THF (polar aprotic solvent), DMSO, Methanol (polar solvent) and water (protic solvent). In addition variation of dipole moment and charges on atoms in the solvents are studied. With the help of TD-DFT study, the electrostatic effects of different solvents and the energy difference between the excited electronic states noticeably depends on the size of the solute cavity used in the PCM calculations. On the basis of the thermodynamic properties of the title compound at different temperatures have been calculated in gas phase, reverling the correlations between standard heat capacities (C), standard entropies (S), standard enthalpy (H) and vibrational and rotational temperatures. The solvation influence on the geometrical parameters, atomic charges and HOMO-LUMO energies was estimated with the use of PCM method. The presence of solvent did not alter these parameters, but affected the orbital energies. The aggregation phenomena were studied with dimer and trimer structure of the title compound.

Origin of 5-hydroxymethylfurfural stability in water/dimethyl sulfoxide mixtures

In the present work, we combined vibrational spectroscopy with electronic structure calculations to understand the solvation of HMF in DMSO, water, and DMSO/water mixtures and to provide insights into the observed hindrance of HMF rehydration and aldol condensation reactions if it is dissolved in DMSO/water mixtures. To achieve this goal, the attenuated total reflection FTIR spectra of a wide composition range of binary and ternary mixtures were measured, analyzed, and compared to the findings of ab initio DFT calculations. The effect of solvent on the HMF C-O and O-H vibrational modes reveals significant differences that are ascribed to different intermolecular interactions between HMF and DMSO or water. We also found that DMSO binds to HMF more strongly than water, and interactions with the HMF hydroxyl group are stronger than those with the HMF carbonyl group. We also showed the preferential solvation of HMF C-O groups by DMSO if HMF is dissolved in DMSO/water mixed solvent. Frontier molecular orbital theory was used to examine the influence of the solvent on side reactions. The results show that HMF solvation by DMSO increases its LUMO energy, which reduces its susceptibility to nucleophilic attack and minimizes undesirable hydration and humin-formation reactions. This result, together with the preferential solvation of HMF by DMSO, provide an explanation for the enhanced HMF stability in DMSO/water mixtures observed experimentally.

Effect of intermolecular hydrogen bonding, vibrational analysis and molecular structure of 4-chlorobenzothioamide

In the present work, the experimental and theoretical vibrational spectra of 4-chlorobenzothioamide were investigated. The FT-IR (400-4000 cm(-1)) and μ-Raman spectra (100-4000 cm(-1)) of 4-chlorobenzothioamide in the solid phase were recorded. The geometric parameters (bond lengths and bond angles), vibrational frequencies, Infrared and Raman intensities of the title molecule in the ground state were calculated using ab initio Hartree-Fock and density functional theory (B3LYP) methods with the 6-311++G(d,p) basis set for the first time. The optimized geometric parameters and the theoretical vibrational frequencies were found to be in good agreement with the corresponding experimental data and with the results found in the literature. The vibrational frequencies were assigned based on the potential energy distribution using the VEDA 4 program. The dimeric form of 4-chlorobenzothioamide was also simulated to evaluate the effect of intermolecular hydrogen bonding on the vibrational frequencies. It was observed that the N-H stretching modes shifted to lower frequencies, while the in-plane and out-of-plane bending modes shifted to higher frequencies due to the intermolecular N-H···S hydrogen bond. Also, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and diagrams were presented.

Testing a new analytical approach for determination of vibrational transition moment directions in low symmetry planar molecules: 1-D- and 2-D-naphthalene

A new analytical approach for improving the precision in determination of vibrational transition moment directions of low symmetry molecules (lacking orthogonal axes) is discussed in this paper. The target molecules are partially uniaxially oriented in nematic liquid crystalline solvent and are studied by IR absorption spectroscopy using polarized light. The fundamental problem addressed is that IR linear dichroism measurements of low symmetry molecules alone cannot provide sufficient information on molecular orientation and transition moment directions. It is shown that computational prediction of these quantities can supply relevant complementary data, helping to reveal the hidden information content and achieve a more meaningful and more precise interpretation of the measured dichroic ratios. The combined experimental and theoretical/computational method proposed by us recently for determination of the average orientation of molecules with C(s) symmetry has now been replaced by a more precise analytical approach. The new method introduced and discussed in full detail here uses a mathematically evaluated angle between two vibrational transition moment vectors as a reference. The discussion also deals with error analysis and estimation of uncertainties of the orientational parameters. The proposed procedure has been tested in an analysis of the infrared linear dichroism (IR-LD) spectra of 1-D- and 2-D-naphthalene complemented with DFT calculations using the scaled quantum mechanical force field (SQM FF) method.

Experimental (FT-IR and FT-Raman) and theoretical (HF and DFT) investigation, NMR, NBO, electronic properties and frequency estimation analyses on 2,4,5-trichlorobenzene sulfonyl chloride

The present work deals with the structural, electronic, and vibrational analyses of the biomolecule 2,4,5-trichlorobenzene sulfonyl chloride (TCBSC). TCBSC is a novel pharmaceutical compound used in dyes, pesticides, pigments, fluorescence brighteners and intermediate for agricultural chemicals in the manufacture of insecticides. Quantum chemical calculation of geometrical structure and energies of TCBSC was carried out by density functional theory (B3LYP) and ab initio (HF) methods at 6-311+G(d,p) and 6-311++G(d,p) standard basis set. The stability of the molecule arising from hyperconjugative interaction and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. NMR analysis shows that the isotropic chemical shifts of carbon and hydrogen atom of TCBSC are giving the reasonable shielding to the molecule. Another interesting property shows nonlinear optical (NLO) behavior. Moreover, we have not only simulated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) but also determined the transition state and energy band gap.

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.

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.

Density functional theory study on characterization of 3-chloro-1,2-benzisothiazole

The FT-IR and FT-Raman spectra of 3-chloro-1,2-benzisothiazole (CBT) have been recorded and analyzed. Theoretical information on the optimized geometry, harmonic vibrational frequencies, infrared and Raman intensities were obtained by means of density functional theory (DFT) gradient calculations, using 6-311++G(d,p) basis set. Mulliken population analysis shows charge distribution on the molecule. Thermodynamic properties like entropy, heat capacity, zero point energy have been calculated for the molecule. The calculated HOMO and LUMO energies show the charge transfer occurs within the molecule. Stability of the molecule has been analyzed using Natural Bond Orbital (NBO) and Natural Localized Molecular Orbital (NLMO) analysis. The results of the calculations were applied to simulated spectra of the title compound, which show the excellent agreement with the observed spectra.

FT-IR, FT-Raman, ab initio, HF and DFT studies, NBO, HOMO-LUMO and electronic structure calculations on 4-chloro-3-nitrotoluene

In this work, the vibrational spectral analysis was carried out by using Raman and infrared spectroscopy in the range 100-4000 cm(-1) and 50-4000 cm(-1), respectively, for 4-chloro-3-nitrotoluene (C7H6NO2Cl) 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 calculated HOMO and LUMO energies shows that charge transfer within the molecule. The effects due to the substitutions of methyl group, nitro group and halogen were investigated. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) and thermodynamic properties were performed.

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.

Vibrational spectroscopic analysis of 2-chlorotoluene and 2-bromotoluene: a combined experimental and theoretical study

In this work, the vibrational spectral analysis was carried out using Raman and infrared spectroscopy in the range 100-4000 cm(-1) and 50-4000 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 wave numbers 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 substitutions of methyl group and halogen bond were investigated. The results of the calculations were applied to simulated spectra of the title compounds, which show excellent agreement with observed spectra.