Study on structural and spectral properties of isobavachalcone and 4-hydroxyderricin by computational method

• The harmonic frequencies and NMR chemical shifts were calculated at the B3LYP/6-311G (d, p) level of theory.
• The electronic absorption spectra were calculated using the TDDFT methodology at the B3LYP/6-311G (d, p) and PBE1PBE/6-311G (d, p) levels of theory.
• B3LYP has been proved to be a good method to study the vibrational spectroscopic and NMR spectral properties of the two chalcones.
• Substitution of different electron donating groups alters the absorption properties and shifts the spectra to a higher wavelength region.

Isobavachalcone and 4-hydroxyderricin, two major chalcone constituents isolated from the roots of Angelica keiskei KOIDZUMI, exhibit numerous biological activities. Quantum chemical methods have been employed to investigate their structural and spectral properties. The ground state structures were optimized using density functional B3LYP method with 6-311G (d, p) basis set in both gas and solvent phases. Based on the optimized geometries, the harmonic vibrational frequency, the 1H and 13C nuclear magnetic resonance (NMR) chemical shift using the GIAO method were calculated at the same level of theory, with the aim of verifying the experimental values. Results reveal that B3LYP has been a good method to study their vibrational spectroscopic and NMR spectral properties of the two chalcones. The electronic absorption spectra were calculated using the time-dependent density functional theory (TDDFT) method. The solvent polarity effects were considered and calculated using the polarizable continuum model (PCM). Results also show that substitutions of different electron donating groups can alter the absorption properties and shift the spectra to a higher wavelength region.

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