Molecular structure, spectroscopic (FT-IR and UV-Vis) and DFT quantum-chemical studies on 2-[(2,4-Dimethylphenyl)iminomethyl]-6-methylphenol

Abstract

To cite this article: Hasan Tanak (2014) Molecular structure, spectroscopic (FT-IR and UV-Vis) and DFT quantum-chemical studies on 2- [(2,iminomethyl]-6-methylphenol, Density functional calculations of the structure, vibrational spectra, molecular electrostatic potential and thermodynamic functions have been performed at the B3LYP/6-311 ++ G(d,p) level of theory for the Schiff base compound 2-[(2,4-Dimethylphenyl)iminomethyl]-6-methylphenol. Experimental and theoretical Fourier transform infrared (FT-IR) studies of the title compound show the preference of enol form, as supported by X-ray analysis results. Using the time-dependent density functional theory (TD-DFT) method, electronic absorption spectra of the compound have been predicted and a good agreement is determined with the experimental ones. To investigate the tautomeric stability, optimisation calculations at B3LYP/6-311 ++ G(d,p) level were performed for the enol and keto forms of the title compound. Calculated results show that its enol form is more stable than that of the keto form. The predicted non-linear optical properties of the title compound are much greater than those of urea. The changes in thermodynamic properties for the formation of the title compound with the temperature ranging from 200 K to 500 K have been obtained using the statistical thermodynamic method. At 298.15 K the change of Gibbs free energy for the formation reaction of the title compound is 37.03 kJ/mol. The title compound cannot be spontaneously produced from the isolated monomers at room temperature. The tautomeric equilibrium constant is also computed as 1.23 × 10 −3 at 298.15 K for enol ↔ keto tautomerisation of the title compound.

Computational Studies on the Molecule 1-(2-Hydroxyethyl)-5-Fluorouracil in Gas Phase and Aqueous Solution and Prediction of Its Confinement inside Capped Nanotubes

“…The m value of urea computed at the B3LYP/6−31+G(d) level is 0.526 × 10 −30 cm 5 /esu. This value is slightly lower than the value reported in the literature at B3LYP/6−31++G(d,p) level ( m = 0.770×10 −30 cm 5 /esu) [48]. The m value of the studied molecule is 1.487 × 10 −30 cm 5 /esu, which is theoretically 2.82 times greater than that of urea at B3LYP/6−31+G(d) level.…”

Molecular structure, spectroscopic and DFT computational studies on 4,5-bis(tert-butylsulfanyl)phthalonitrile

“…From Table 4, the calculated polarizability a ij have nonzero values and was dominated by the diagonal components. The total first hyperpolarizability value b tot of the title compound is equal to 10.384 Â 10 À30 cm 5 /esu which is greater than that of urea (the b tot of urea is 0.77 Â 10 À30 cm 5 /esu obtained by B3LYP/6-311++G(d,p) method) [49]. The first-order hyperpolarizability of the title compound is of 13.48 times magnitude of urea, theoretically.…”

“…6. The HOMO-LUMO energy gaps were calculated as 4.035 eV for the title compound, 4.327 eV for 3-(2-Mercaptopyridine)phthalonitrile [4] and 6.702 eV for urea by B3LYP/6-311++G(d,p) method [49]. As can be seen from the b tot values for these compounds, there is an inverse relationship between first hyperpolarizability and HOMO-LUMO gap, allowing the molecular orbitals to overlap to have a proper electronic communication conjugation, which is a marker of the intramolecular charge transfer from the electrondonating group through the p-conjugation system to the electron-accepting group [49].…”

Vibrational Spectroscopic and Computational Studies on Bis(2-aminopyridinium)fumarate - Fumaric Acid (1:1) Complex

“…The single crystal X-ray diffraction experimental results are given as input to the Gaussian program to obtain the molecular geometry. Vibrational frequencies were scaled by 0.9613 [19]. The assignment of the calculated normal modes has been made on the basis of the corresponding PEDs.…”