FT-IR, FT-Raman and UV spectroscopic investigation, electronic properties, electric moments, and NBO analysis of anethole using quantum chemical calculations

• Spectroscopic analysis of anethole were examined by FT-IR, FT-Raman and UV–vis techniques.
• A good agreement between the calculated and experimental wavenumbers.
• The Trans-anethole has large βTOTAL value, almost 33 times greater than urea.
• OPDOS shows LUMO with significant π* interaction between propenyl group and phenyl ring.

FT-IR and FT-Raman spectra of anethole (1-Methoxy-4-(1-propenyl)benzene), a flavoring agent of commercial value, have been recorded in the regions 4000–400 and 4000–100 cm−1 respectively. The structure of the title molecule has been optimized and the structural parameters have been calculated by DFT/B3LYP method with 6-311++G(d,p) basis set. The fundamental vibrational wavenumbers as well as their intensities were calculated and a good agreement between observed and scaled calculated wavenumbers has been achieved. UV–Vis spectrum of the title compound was recorded in the region 200–500 nm and the electronic properties such as HOMO and LUMO energies and associated energy gap were calculated by Time dependent-density functional theory (TD-DFT) approach. Nonlinear optical (NLO) study divulges the nonlinear properties of the molecule. Stability of the title molecule arising from hyper-conjugative interactions and charge delocalization has been investigated using natural bond orbital (NBO) analysis. The theoretical results were found to be in coherence with the measured experimental data.

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