Ab initio HF, DFT and experimental (FT-IR) investigation of vibrational spectroscopy of P-N,N-dimethylaminobenzylidenemalononitrile (DBM)

The optimized geometry and vibrational frequencies of P-N,N-dimethylaminobenzylidenemalononitrile (DBM) were obtained by ab initio HF and DFT/B3LYP levels with complete relaxation in the potential energy surface using 6-31++G(d,p) and 6-311++G(d,p) basis sets. The Fourier-transform infrared (FT-IR) spectrum of DBM has been recorded in the region 4000–400 cm−1. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR spectrum. The calculated frequencies are in good agreement with the experimental frequencies.

Graphical abstractAb initio HF, DFT and experimental (FT-IR) study has been carried out on DBM compound. The assignments made at higher levels of theory, i.e., B3LYP/6-311++G(d,p), gives reasonable deviations from the experimental values. PM3 semiemperical calculation was done to obtain some physical properties of this molecule. It is concluded that, the change in the total dipole moment enhances the reactivity of DBM and making it as a promising material for solar cell applications.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► DBM compound is of the type donor-phenyl-acceptor (D-ph-A). ► B3LYP/6-311++G(d,p) level gives reasonable deviations from the experimental values. ► The DBM compound possesses high value of dipole moment (10–12 Debye). ► The DBM compound can be used to manufacture D/A solar cells. ► The physical properties of DBM compound were enhanced by energy irradiation.