Resumo

RAHMANI, Rachida et al. Molecular Structure, FT-IR, NMR (¹³C/¹H), UV-Vis Spectroscopy and DFT Calculations on (2Z, 5Z)-3-N(4-Methoxy phenyl)-2-N'(4-methoxy phenyl imino)-5-((E)-3-(2-nitrophenyl)allylidene) thiazolidin-4-one. S.Afr.j.chem. (Online) [online]. 2019, vol.72, pp.176-188. ISSN 1996-840X.  http://dx.doi.org/10.17159/0379-4350/2019/v72a23.

In this study, some molecular properties of (2Z, 5Z)-3-N(4-methoxy phenyl)-2-N'(4-methoxy phenyl imino)-5-((E)-3-(2-nitro-phenyl) allylidene) thiazolidin-4-one (MNTZ) are evaluated using a combination of spectroscopic characterization (FT-IR, ¹H and ¹³C NMR chemical shifts) and theoretical calculations. Molecular geometry, vibrational wavenumbers, gauge-independent atomic orbital (GIAO), ¹H and ¹³C chemical shift values and NBO analysis are investigated using B3LYP and PBE functionals with the 6-31G(d,p) basis set in the ground state. The calculated geometrical parameters and vibrational spectra are compared to available experimental data and each vibrational frequency is assigned on the basis of potential energy distribution (PED). The electronic transitions are calculated using time-dependent density functional theory (TDDFT). The energy band gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies are obtained by computing the frontier molecular orbitals using the B3LYP/6-31G(d,p) and PBE/6-31G(d,p) levels along with the global reactivity descriptors. Mulliken atomic charges and molecular electrostatic potential (MEP) are simulated using both functionals to find more reactive sites for electrophilic and nucleophilic attack. Finally, the thermodynamic functions (heat capacity, entropy, and enthalpy) from spectroscopic data are obtained and discussed in the range of 100-1000 K.

Palavras-chave : FT-IR; UV-Vis; HOMO-LUMO; thiazolidinones; DFT; NMR spectra; NBO.

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