FT-IR, FT-Raman, NMR spectral analysis and theoretical NBO, HOMO–LUMO analysis of bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)ethane by ab initio HF and DFT methods

“…By showing the accurate natural Lewis structural picture of model compound, NBO analysis is a powerful tool in understanding various donor-acceptor interactions between the filled and the vacant orbitals of the subsystem [24]. The NBO analysis was performed at B3LYP/6-31G(d) level to elucidate the intra-molecular rehybridization and delocalization of electron density on TBBPA.…”

Section: Nbo Analysismentioning

confidence: 99%

“…where q i is the donor orbital occupancy, while F(i, j) is the off diagonal NBO Fock matrix element, and e i and e j are diagonal elements [24]. The larger of the E (2) value suggests the more intensive interactions between electron-donors and electron-acceptors, and the greater the extent of conjugation of the whole system [25].…”

Section: Nbo Analysismentioning

confidence: 99%

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Vibrational, NMR spectrum and orbital analysis of 3,3′,5,5′-tetrabromobisphenol A: A combined experimental and computational study

Qiu

Jin

Pan

et al. 2013

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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) and FT-Raman (100-4000 cm À1 ) spectra of TBBPA were recorded. The molecular geometry, vibrational frequencies were calculated by using density functional theory (DFT) method with the 6-31G(d) basis set. The optimized geometric properties, scaled vibrational wavenumbers, IR intensities, Raman activities show good agreement with the experimental data. The assigned vibrational modes of the IR and Raman spectra were compared with the corresponding properties of the polybrominated diphenyl ethers (PBDEs). Comparative analysis indicated that the red shift of C-Br vibration could probably be ascribed to the further electronic density equalization due to the p-p conjugation between O atom and the benzene. Analysis of isosurface of the related orbital shows that all the main excitation exhibit p-p Ã character localized on the benzene rings.

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“…The HOMO and LUMO represent the ability to denote and accept electrons. [31,32] These orbitals are termed frontier molecular orbitals (FMOs). The HOMO represents the ability to donate an electron, whereas the LUMO, as an electron acceptor,r epresents the ability to gain an electron.…”

Section: Frontier Molecularorbitals and Reactivityp Arametersmentioning

confidence: 99%

Synthesis, Spectroscopic Characterization, and Time‐Dependent DFT Calculations of 1‐Methyl‐5‐phenyl‐5H‐pyrido[1,2‐a]quinazoline‐3,6‐dione and Its Starting Precursor in Different Solvents

Hamada

2018

ChemistryOpen

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In this study, 2‐mercapto‐3‐phenyl‐2,3‐dihydro‐1H‐quinazolin‐4‐one (1), which exists as a thiol and thione tautomer, was treated with acetylacetone to give the target compound, namely, 1‐methyl‐5‐phenyl‐5H‐pyrido[1,2‐a]quinazoline‐3,6‐dione (2). The spectroscopic data, including UV/Vis, IR, 1H NMR, 13C NMR, and mass data, of this compound were recorded. The molecular structures of the starting material (1) and the product (2) were optimized by using density functional theory (DFT) by employing the B3LYP exchange correlation with the 6‐311G (d, p) and 6‐31G++ (d, p) basis sets. The electronic spectra were determined based on time‐dependent DFT calculations in three different solvents (i.e., chloroform, ethanol, and acetonitrile) starting from the same solvated run of the optimized geometry with the same two basis sets. The solvent effects were considered based on the polarizable continuum model (PCM), and the energetic behavior of the compounds and the total static dipole moment (μ) in different solvents were examined in the two basis sets; the results showed that the total energy of the compounds decreased upon increasing the polarity of the solvent. Time‐dependent DFT calculations were performed to analyze the electronic transitions for various excited states that reproduced the experimental band observed in the UV/Vis spectrum. A study on the electronic properties, such as the HOMO and LUMO energies, was performed by the time‐independent DFT approach. Using the gauge‐independent atomic orbital method (GIAO), the 1H NMR chemical shifts were calculated and correlated with the experimental ones. The computed results showed that the introduction of different dielectric media had a slight effect on the stability and reactivity of the title compound as well as on the Milliken atomic charges and the molecular geometry. Besides, the molecular electrostatic potential of target product 2 was evaluated in different solvents.

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FT-IR, FT-Raman, NMR spectral analysis and theoretical NBO, HOMO–LUMO analysis of bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)ethane by ab initio HF and DFT methods

Cited by 36 publications

References 22 publications

Synthesis and comparison of bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)butane using DFT study

Synthesis and comparison of bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)butane using DFT study

Vibrational, NMR spectrum and orbital analysis of 3,3′,5,5′-tetrabromobisphenol A: A combined experimental and computational study

Synthesis, Spectroscopic Characterization, and Time‐Dependent DFT Calculations of 1‐Methyl‐5‐phenyl‐5H‐pyrido[1,2‐a]quinazoline‐3,6‐dione and Its Starting Precursor in Different Solvents

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