Gaussian 09W Program Research Articles

Pressure dependent phase transformations of energetic material 2,4−dinitroanisole using Raman spectroscopy, X-ray diffraction and first principles calculations

The molecular structure of 2,4−dinitroanisole (DNAN) is optimized using Gaussian 09W program, two stable molecular structures with different methoxy group orientations are obtained and vibrational frequencies are calculated for the two optimized molecular structures. DNAN crystal structure is optimized using CASTEP and VASP codes and phonon frequencies are calculated and assigned. Computed frequencies compare well with experimental values. Pressure dependent phase transformation in DNAN is investigated by Raman spectroscopy and X-ray diffraction. Differences between the Raman spectra of DNAN and trinitrotoluene (TNT) point to a larger phonon energy gap in DNAN to be a possible reason for the lower impact sensitivity of DNAN. Appearance of new Raman bands and discontinuity of the bands above 1.3 GPa indicates a phase transformation. Changes in the X-ray diffraction patterns confirm the phase transformation. The transformation of the ambient monoclinic to an orthorhombic structure starts at around 2 GPa. At 6.8 GPa the monoclinic structure completely transforms into orthorhombic with a volume collapse of 10%. Bulk moduli for the monoclinic and orthorhombic phases are estimated as ∼12 GPa and 27 GPa respectively, pointing to a lower impact sensitivity of the orthorhombic phase.

Theoretical calculation of some chemical properties of the cannabidiol (CBD) molecule

Lately, many products with the active ingredient cannabidiol (CBD) have been sold around the world. Cannabidiol is an annual herb of the cannabis plant that is known to have no euphoric effects. Another type of terpenophenolic compound known as cannabinoids is also preserved in the structure of the cannabis plant. Products containing CBD are offered on the market as drugs, food supplements or dietary supplements. The US Food and Drug Administration FDA (Food and Drug Administration) has approved the oral solution of Epidiolex (cannabidiol) [CBD] for the treatment of epilepsy in patients aged two years and over. The legal assessment of commercial products containing cannabidiol (CBD) depends on the composition of the drugs available in pharmacies. Depending on whether the drugs also contain tetrahydrocannabinol (THC) in their structure in addition to CBD, criminal narcotics convictions are also decisive. In our study, some parameters related to the chemical structure of the cannabidiol (CBD) molecule were calculated using the Gaussian 09W program and the GaussView 5.0 interface program.

Spectroscopic (FT-IR, FT-Raman) investigations, quantum chemical calculations, ADMET and molecular docking studies of phloretin with B-RAF inhibitor

The Phloretin molecule is chemically known as 3-(4-hydroxyphenyl)-1-(2, 4, 6-trihydroxyphenyl) propan-1-one (4H6TP), which was optimized by utilizing B3LYP functional employing 6-311++G(d,p) level of theory. The optimized geometrical parameters such as bond length and bond angle were obtained from 4H6TP by utilizing Gaussian 09W program. Additionally, the ground-state HOMO and the first excited state LUMO energy gap show charge transfer within the molecule. Molecular electrostatic potential (MEP) map is useful in finding the reactive site and physiochemical properties of the title compound. Fukui function, Mulliken population and natural bonding orbital (NBO) were done to describe the reactive site of the title compound. To enhance the quality control of drugs; absorption, distribution, metabolism, excretion and toxicity of 4H6TP were predicted by using computational approaches. A molecular docking study of 4H6TP was carried out and docked effectively in the binding site of B-RAF inhibitor. Computational approaches additionally predict that this molecule possesses great solubility, pharmacokinetic properties and target accuracy. Phloretin molecule also obeys the Lipinski’s rule of five, which makes it a promising compound to scrutinize its potential for use against anti-non-small cell lung cancer.

Study of Suggested Chemotherapy Agent of bis ((S) -3-methoxycarbamoyl pentanoate) di chloride bis (ethyl amine) platinum (IV))MPP) using DFT

Abstract In this paper, we designed the platinum octahedral complex as an anti-cancer drug by applying it to the Gaussian 09W program. The physical properties were calculated using the DFT / B3LYP density function theory for basis sets (LANL2DZ), we also calculated the ultraviolet-visible spectrum (UV), the infrared spectrum (IR), the stability energy, the HOMO and LUMO orbits, the Global properties, and the difference between them and studied the reduction of the octahedral complex to a flat square and its hydrolysis inside the human body, then compared its association with the nitrogenous bases that make up the DNA through nitrogen atom number (N7) and then its association With DNA strand and the results showed that the designed compound achieved high chemical rigidity when linked to methyl. DNA and this indicates its biological effectiveness towards cancer inhibition and compare this result with the well-known treatment against cancer, which is cisplatin, theoretically using the same method and the same basis.

Theoretical Evaluation of the Corrosion Inhibition Performance of an Organic Heterocyclic Compound

The corrosion inhibition performance of a corrosion inhibitor on mild steel in phosphoric acid, namely 5-chloro-1-(2-(dimethylamino) ethyl) indoline-2,3-dione (TZCDI), was theoretically evaluated using density functional theory (DFT) at the B3LYP/6-31G+(d,p) level for all atoms by Gaussian 09W program. The quantum chemical properties, such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO) energy gap (∆Egap), dipole moment (μ), total hardness (η), and electronegativity (χ), were studied, and these descriptors were discussed in connection to the experimental inhibitory efficiency. The local reactivity was analyzed through the Fukui function in order to compare the possible sites for nucleophilic and electrophilic attacks. Accordingly, all data obtained using various theoretical calculation techniques were consistent with experiments.

Structural, spectroscopic, electronic, and nonlinear optical behavior investigations of  conjugated organic nonlinear optical chalcone derivative 3-(2,3-dichlorophenyl)-1-(pyridine-2-yl)prop-2-en-1-one using DFT

In this paper we have reported the computational studies of structural, spectroscopic and electronic behavior of a chalcone derivative: 3-(2,3- dichlorophenyl )-1-(pyridine-2- yl)prop-2-en-1-one (DCPP) nonlinear optical crystal. The geometry of DCPP molecule have been optimized using density functional theory (DFT) at B3LYP level having extended basis sets 6-311++G(d,p), 6-311+G(d,p), and 6-311G(d,p) with the help of Gaussian 09W program package. The structure parameters calculated with 6-311++G(d,p) basis set have shown best matching with experimental data having R 2 value equal to 0.99. Taking this optimized geometry FTIR spectra were simulated and analyzed quantitatively with the help of calculated potential energy distribution (PED). For finding the reactivity sites and to understand electronic and optical behavior, natural bond orbital (NBO), the electrostatic potential surface map with isodensity surface, and HOMO-LUMO analysis were also presented. Finally, the nonlinear optical behavior of this calcone derivative was studied by calculating dipole moment (m), polarizability(a) and hyperpolarizability (b) values. The calculated hyperpolarizability b tot of DCPP is 17.4593×10 -30 esu which is about 90 times greater than urea (β= 0.1947× 10-30 esu). This higher value of hyperpolarizability b tot confirms that the present molecule DCPP is a potential candidate for Nonlinear Optical applications.

Molecular, Electronic, Nonlinear Optical and Spectroscopic Analysis of Heterocyclic 3-Substituted-4-(3-methyl-2-thienylmethyleneamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones: Experiment and DFT Calculations

Abstract In the present study, 3-p-methoxybenzyl/m-chlorobenzyl/phenyl-4-(3-methyl-2-thienylmethyleneamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones were obtained from the reaction between 3-methylthiophene-2-carbaldehyde and three different 4-amino-(3-p-methoxybenzyl/m-chlorobenzyl/phenyl)-4,5-dihydro-1H-1,2,4-triazole-5-ones. In order to compare experimental and theoretical values, the geometric parameter, electronic, nonlinear optical properties, molecular electrostatic potentials and spectroscopic properties of 3-substituted-4-(3-methyl-2-thienylmethyleneamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones have been simulated. The electronic properties of the newly synthesized compounds were calculated using DFT/B3LYP and DFT/B3PW91 methods revealing parameters such as ionization potential, electron affinity, energy gap, electronegativity, molecular hardness, molecular softness, electrophilic index, nucleophilic index and chemical potential, all obtained from HOMO and LUMO energies, dipole moments and total energies. UV-visible absorption spectra and the stimulation contributions in UV-visible transitions were obtained by using TD-DFT/B3LYP/6-311G(d,p) and TD-DFT/B3PW91/6-311G(d,p) methods in ethanol. The calculated absorption wavelengths, oscillator power and excitation energies were compared with experimental values. In line with DFT, the numbers of molecular vibration were analyzed through the basis set of 6-311G(d,p). The recording of FT-IR frequencies was done for the pertinent compound. The recorded frequencies through DFT/B3LYP and DFT/B3PW91 methods were compared to experimental values, with a result gained closest to the values of B3LYP. Finally, the Gaussian09W program package in DMSO phase, starting from the optimized structure, has been instrumental in calculating the 13C-NMR and 1H-NMR chemical shift values of the GIAO method.

Molecular modelling, spectroscopic characterization and nonlinear optical analysis on N-Acetyl-DL-methionine

In this present methodical study, on the basis of the density functional theory (DFT), the first-principles calculations have been employed successfully to study the structural and electronic properties of N-acetyl-DL-methionine (C7H13NO3S) which is a derivative of DL-methionine which is also known DL-2-amino-4-methyl-thiobutanoic acid. Optimized molecular structure, vibrational frequencies and also 13C and 1H NMR chemical shift values of the title compound are provided in a detailed manner by using B3LYP and HSEH1PBE functionals by applying 6-311++G(d,p) basis set for calculations using Gaussian 09W program. The comparison of the calculated values with the experimental values provides important information about the title compound. In addition, the electronic properties (UV-Vis calculations) of the title compound, such as HOMO-LUMO energy values and energy gap, absorption wavelengths, oscillator strengths were performed basing on the optimized structure in gas phase. Moreover, the molecular electrostatic potential surface, dipole moment, nonlinear optical properties, linear polarizabilities and first hyperpolarizabilities and chemical parameters have also been studied.

Single crystal, Hirshfeld surface and theoretical analysis of methyl 4-hydroxybenzoate, a common cosmetic, drug and food preservative-Experiment versus theory.

Methyl 4-hydroxybenzoate, commonly known as methyl paraben, is an anti-microbial agent used in cosmetics and personal-care products, and as a food preservative. In this study, the single crystal X-ray structure of methyl 4-hydroxybenzoate was determined at 120 K. The crystal structure comprises three methyl 4-hydroxybenzoate molecules condensed to a 3D framework via extensive intermolecular hydrogen bonding. Hirshfeld surface analysis was performed to determine the intermolecular interactions and the crystal packing. In addition, computational calculations of methyl 4-hydroxybenzoate were obtained using the Gaussian 09W program, and by quantum mechanical methods, Hartree Fock (HF) and Density Functional Theory (DFT) with the 6–311G(d,p) basis set. The experimental FT-IR spectrum strongly correlated with the computed vibrational spectra (R2 = 0.995). The energies of the frontier orbitals, HOMO and LUMO, were used to calculate the chemical quantum parameters. The lower band gap value (ΔE) indicates the molecular determinants underlying the known pharmaceutical activity of the molecule.

Green Synthesis of Triazole-Based Chemosensors and their Efficacy Towards Mercury Sensing

Background: The synthesis of small organic molecules based Hg2+ ions receptors have gained considerable attention because it is one of the most prevalent toxic metals which is continuously discharged into the environment by different natural and industrial activities. 1,4-Disubstituted 1,2,3-triazoles have been reported as good chemosensors for the detection of various metal ions including Hg2+ ions. Methods: The synthesis of 1,2,3-triazoles (4a-4c) was achieved by Cu(I)-catalyzed azide-alkyne cycloaddition, and their binding affinity towards various metal ions and anions were studied by UVVisible titration experiments. The perchlorate salts of metal ions and tetrabutylammonium salts of anions were utilized for the UV-Visible experiments. DFT studies were performed to understand the binding and mechanism on the sensing of 4a toward Hg2+ using the B3LYP/6-311G(d,p) method for 4a and B3LYP/LANL2DZ for 4a-Hg2+ species on the Gaussian 09W program. Results: The UV-visible experiments indicated that the compounds 4a-4c show a selective response towards Hg2+ ion in UV-Visible spectra, while other ions did not display such changes in the absorption spectra. The binding stoichiometry was evaluated by Job’s plot which indicated the 1:1 binding stoichiometry between receptors (4a-4c) and Hg2+ ion. The detection limit of 4a, 4b and 4c for the Hg2+ ions was found to be 29.1 nM, 3.5 μM and 1.34 μM, respectively. Conclusion: Some 1,2,3-triazole derivatives were synthesized (4a-4c) exhibiting high selectively and sensitivity towards Hg2+ ions in preference to other ions. Compound 4a has a low detection limit of 29.1 nM and the binding constant of 2.3×106 M-1. Similarly, 4b and 4c also showed selective sensing towards Hg2+ ions in the μM range. The observed experimental results were corroborated by density functional theory (DFT) calculations.

Density Functional Theory Calculation of Molecular Descriptors for Simple Coumarins in Gas and Different Solvents

The primary aim of this study is to show the importance of molecular structure analysis of pharmaceutical active coumarins compounds using quantum chemistry methods based on density functional theory. To explore the theoretical calculations for global descriptors, the standard Gaussian 09W program was used for coumarins compounds. The full geometry optimization was carried out by the B3LYP/6-311G level of theory. The octanol-water and air-water partition coefficients were also estimated using functional density theory. The order of the HOMO-LUMO energy gap for studied coumarins in the gas phase is umbelliferone (UBA) < (herniarin) HNR ~ (crenulatin) CNT < (scopoletin) SCT < (scoparone) SCO < (isoscopoletin) IST < (4-methylesculetin) MST < (umbelliferone-2- carboxylic acid) UCA < (isofraxidin) IFD < (fraxetin) FXT < (aesculetine) ACT < (dapnetine) DPT. Therefore, UBA molecule in gas phase is less stable. Compared to the measured index of electrophilicity (DE). The MST molecule is stronger, more reactive, nucleophile electrophile at the gas phase and in solvents. In all solvent phases, CNT and UCA molecules have lower values, which mean they are strong nucleophiles. From the log P values of ACT and MST coumarins are in between 1.35-1.8, so ACT and MST coumarins use oral and intestinal absorptions.

Investigation on Molecular Structure, Vibrational Analysis and Thermodynamic Properties of 1-(2,6-dimethylmorpholine-4-yl-methyl)-3-methyl-4-[3-ethoxy-(4-benzenesulfonyloxy)- benzylidenamino]-4,5-dihydro-1H-1,2,4-triazol-5-one

In this article, 1-(2,6-dimethylmorpholine-4-yl-methyl)-3-methyl-4-[3-ethoxy-(4-benzenesulfonyloxy)-benzylidenamino]-4,5-dihydro-1H-1,2,4-triazol-5-one has been theoretically studied. All quantum chemical calculations were carried out by using Gaussian 09W program package and GaussView molecular visualization program. The 1H and 13C NMR chemical shifts of the title molecule were calculated by the GIAO method and compared with experimental results. Theoretical and experimental values were plotted according to dexp=a+b. d calc. The standard error values were found via the Sigma plot with regression coefficient of a and b constants. The vibrational frequency values of this compound have been calculated by using 6-31G(d,p) basis set with DFT and HF methods and these values are multiplied with appropriate adjustment factors. The veda4f program was used in defining IR data. The polarizability (α), hyperpolarizability (β), dipole moment along with molecular electrostatic potential surface have been calculated. The molecular electrostatic potential (MEP) map was calculated to assign reactive site on the surface of the molecule. The calculated electronic, structural (bond lengths and bond angles) and several thermodynamic parameters of title molecule were performed using the Hartree-Fock (HF) and density functional methods (DFT/B3LYP) with 6-31G(d,p) basis set.

Hirshfeld Surface analysis, spectroscopic, biological studies and molecular docking of (4E)-4-((naphthalen-2-yl)methyleneamino)-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one

Abstract In the present work, the newly synthesized compound (4E)-4-((naphthalen-2-yl)methyleneamino)-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one was studied by both structural and spectral (FT-IR, 1H and 13C NMR chemical shifts and electronic-UV-Vis.), using experimental and theoretical methods. All theoretical computations of the title compound were performed by using the density functional theory (DFT/B3LYP) quantum mechanical method with 6–311++G(d,p) basis set and Gaussian 09W program. The vibrational assignments were controlled and performed with VEDA 4 program based on potential energy distributions (PED). The experimental FT-IR spectrum was studied in solid phase in the range of 4000 and 400 cm−1. Also, the experimental and theoretical 1H and 13C NMR chemical shifts in chloroform and UV–Vis. spectral analysis in methanol were examined theoretically and experimentally. To support UV–Vis. data (both experimental and theoretical), the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) computations were carried out over with methanol optimized structure. Furthermore, Hirshfeld and MEP (Molecular Electrostatic Potential) surface analyses were performed to observe better intermolecular interactions in the crystal packing. Antimicrobial studies showed that the compound has inhibition zones with different sizes with various microorganisms, indicating the different interactions of the examined compound with the growth, cell wall structure and permeability of cell membrane of the tested organisms. Furthermore, molecular docking studies were conducted for the Schiff base compound and appropriate reference drugs against 5fsa and 1kzn proteins, highlighting the different mode of interactions assumed by the Schiff base compound compared to that of the reference drugs which rationalize the difference in biological effects.

Molecular docking, Hirshfeld surface analysis and spectroscopic investigations of 1-(adamantan-1-yl)-3-(4-fluorophenyl)thiourea: A potential bioactive agent

In this study, the optimized molecular structure, Hirshfeld surface analysis, vibrational frequencies and corresponding vibrational modes of a potential bioactive agent namely; 1-(adamantan-1-yl)-3-(4-fluorophenyl)thiourea were studied experimentally and theoretically. The theoretical calculations of the title compound were carried out using the density functional theory (DFT/B3LYP and DFT/M06-2X) quantum mechanical method with 6-311++G(d,p) basis set and Gaussian 09W program. The vibrational assignments of the title compound were obtained using VEDA 4 program by %10 precision with the help of potential energy distributions (PED). The experimental (FT-IR and Laser-Raman) spectra were recorded in solid phase at 4000–400 cm−1 (FT-IR) and 4000–100 cm−1 (Laser-Raman). Additionally, the experimental and theoretical 1H and 13C NMR chemical shifts in DMSO‑d6 and UV–Vis. Spectral analysis in DMF were studied theoretically and experimentally. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) analyses were performed. The molecular docking studies of the title compound revealed that it may exhibit antibacterial activity via inhibition of bacterial DNA gyrase PDB: 3U2D enzyme.

Macrocyclic Schiff base complexes as potent antimicrobial agents: Synthesis, characterization and biological studies.

A series of CuII, CoII, ZnII and NiII, complexes of 34,74-dimethyl-12,15,52,55-tetrahydro-2,4,6,8-tetraaza-1,5(2,5)-difurana-3,7(1,2)-dibenzenacyclooctaphane based ligand have been synthesized by template methodology. Characterization of the synthesized complexes has been carried out with the help of various physicochemical and spectroscopic techniques like Infra-Red, ESI-MS, ESR, UV-visible, CHN (elemental analyses), molar conductance, magnetic moment and NMR. Antimicrobial efficacy of the newly designed macrocyclic complexes has performed by the assistance of agar well diffusion method. In-vitro hemolytic and DNA binding studies were also performed in order to analyze or interpret the mode and binding efficiencies as well as the % hemolysis exhibited by the complexes. DFT/TD-DFT studies were carried out in order to elucidate the better insight into the structural parameters. Energy minimization and quantum chemical parameters were calculated using Gaussian09W program.

Investigation of theoretical properties of 1-Acetyl-3-(p-methylbenzyl)-4-(3-methyl-2- thienylmethyleneamino)-4,5-dihydro-1H-1,2,4-triazol-5-one molecule

In this study, firstly, 1-acetyl-3-(p-methylbenzyl)-4-(3-methyl-2-thienylmethyleneamino)-4,5-dihydro-1H-1,2,4-triazol -5-one molecule was optimized by using the B3LYP/DFT631G (d) and HF/631G (d) basis sets. Then, the veda4f program was used in defining of IR data theoretically. IR (infrared) vibrational frequencie values with two different basis sets of molecule was calculated in gas phase and multiplied by adjustment scale factors. Infrared spectra of molecule according to these values obtained were formed. Furthermore, 1H-NMR and 13C-NMR isotropic shift values were calculated by GIAO method. Experimental and theoretical values of analyzed molecule were inserted into the graphic according to equation of δ exp =a + b. δ calc. The standard error values were found via SigmaPlot program with regression coefficient of a and b constants. Finally, bond angles, bond lengths, mulliken atomic charges, HOMO-LUMO energy, ELUMO-EHOMO energy gap (ΔE), electronegativity (χ), electron affinity (A), global hardness (η), softness (σ), ionization potential (I), total energy of the molecule, dipole moment and thermodynamic properties were calculated with Gaussian 09W program.

EXPERIMENTAL AND THEORETICAL ANALYSIS OF N,N’-(ETHANE-1,2-DIYLBIS(4,1-PHENYLENE))BIS(1-(THIOPHEN-2-YL)METHANIMINE) AND N,N’-(ETHANE-1,2-DIYLBIS(4,1-PHENYLENE))BIS(1-(4-METHYLTHIOPHEN-2-YL)METHANIMINE) SCHIFF BASE LIGANDS

N,N’-(ethane-1,2-diylbis(4,1-phenylene))bis(1-(thiophen-2-yl)methanimine) and N,N’-(ethane-1,2-diylbis(4,1-phenylene))bis(1-(4-methylthiophen-2-yl) methanimine) ligands are formed by diamine and two aromatic aldehyde using Schiff base condensation method. Ligands are characterised by fourier transform infrared spectroscopy (FT-IR), 1H- and 13C- nuclear magnetic resonance spectroscopy (1H- and 13C- NMR) and mass spectroscopy (LC ESI/MS) methods. Furthermore, geometric properties such as bond lenghts, bond angles, dihedral angles, electronic properties, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies are calculated by using Gaussian 09w program. Experimental and theoretical spectrum datas are compared.

Comparative Analysis of Molecular Structure, Vibrational Spectral Studies and Nlo Properties of 3-Hydroxy-4methoxy-Benzaldehyde and 4-Hydroxy-3-Methoxy-Benzaldehyde by DFT

Benzaldehyde is best known as being artificial essential oil of almond and it has many other uses such as; the manufacturing of dyes, perfumes, flavourings, cinnamic and mandelic acids, and it is also used as a solvent. Some more recent developments in the use of benzaldehyde are for the health and agriculture industries. Due to these basic reasons there exist a vast field of study of substituted benzaldehydes. In the present study a comparative analysis is done between 3-hydroxy-4-methoxy-benzaldehyde and 4-hydroxy-3-methoxy-benzaldehyde. The spectral studies were performed for FTIR, IR (KBr and Nuzol) and Raman. Quantum mechanical calculations of geometries, energies, vibrational wave numbers and thermodynamic constants have been performed with Gaussian 09W program package using the Becke-3Lee-Yang-Parr (B3LYP) functional supplemented with the standard 6-31G (DP). The optimised geometrical parameters obtained by computational method used shows good agreement with the experimental data. The thermodynamic properties as heat capacity, entropy, enthalpy and Gibb’s free energy of the titled compounds at different temperatures were also calculated along with dipole moment, polarisability and hyperpolarisability.

New bis 1,3,4-oxadiazole derivatives: syntheses, characterizations, computational studies, and antioxidant activities

In this study, two new bis oxadiazole derivatives (2a and 2b) were synthesized. The new compounds were characterized by elemental analyses, IR, 1H NMR, 13C NMR, and mass spectral studies and were tested for their antioxidant activity. According to the results, it was observed that the synthesized compounds (2a and 2b) had a very high activity in both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing ability of plasma (FRAP) tests. The approximate geometries of the compounds 2a and 2b were prepared with GaussView5 visualization program. The optimized molecular geometric parameters, vibrational wavenumbers, UV–vis parameters, and HOMO–LUMO simulations were computed using Gaussian 09W program. The computations were performed at 6-311++G(d,p) basis set using the B3LYP functional in density functional theory (DFT) method. The harmonic vibrational wavenumbers computed in gas phase were scaled with 0.958 (1700–4000 cm−1) and 0.983 (0–1700 cm−1) for the B3LYP/6-311++G(d,p) level. To calculated the UV–vis spectroscopic parameters with TD-DFT method, the compounds 2a and 2b were optimized in DMF and DMSO solvents using the integral equation formalism polarizable continuum model (IEFPCM) method at the B3LYP/6-311++G(d,p) level. The HOMO, LUMO, and UV–vis analyses were studied to interpret intramolecular charge transfers.

Schiff Bazlı C16H16BrNO3 Molekülünün Yapısal, Konformasyonel ve Spektoskopik Özellikleri: Teorik İnceleme

The Schiff- bases compound C16H16BrNO3 molecular geometry, vibrational frequencies and electronic properties(total energy, dipole moment, electronegativity, chemical hardness and softness) were investigated using DFT(B3LYP) method. Besides, the conformational analysis was made with respect to selected degrees of torsional freedom τ(C3-C2-C1-N1)torsional. Molecular electrostatic potential (MEP), frontier molecular orbital energies and NBO analysis of molecule have been performed by using Gaussian 09W program. The NLO analysis indicates that this molecule can be evaluated as an attractive object for nonlinear optical material studies.