Spectroscopic and theoretical studies of 2-acetylbenzo[b]selenophen-3(2H)-one

In the present study, the FT-IR spectrum of 2-acetylbenzo[b]selenophen-3(2H)-one (2ACSeP, C₁₀H₈O₂Se) has been recorded in the range of 4000–400 cm⁻¹. The molecular structure of 2ACSeP in the ground state has been investigated by the density functional method (B3PW91) with 6-31G(d,p), 6-311G(d,p), 6-311G(2df,p) and 6-311G(3df,3pd) basis sets. From the potential energy surface calculation, there are two conformers, s-cis and s-trans for this molecule. The computational results diagnose the most stable conformer of 2ACSeP as the s-trans form. Making use of the recorded data, the complete vibrational assignments are made and analysis of the observed fundamental bands of molecule is carried out. The complete assignments are performed on the basis of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMF). The molecular stability and bond strength were investigated by applying the natural bond orbital analysis (NBO) and natural localized molecular orbital (NLMO) analysis. The electronic properties, such as excitation energies, absorption wavelength, HOMO and LUMO energies were performed by the time dependent DFT (TD-DFT) approach. The ¹H and ¹³C nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge-including atomic orbital (GIAO) method and compared with experimental results.