Ab-initio and DFT calculations on molecular structure, NBO, HOMO–LUMO study and a new vibrational analysis of 4-(Dimethylamino) Benzaldehyde

• The molecular structure 4-(Dimethylamino) Benzaldehyde has been optimized by ab initio and DFT methods.
• The vibrational frequencies and UV–visible spectrum have been calculated and correlated with the experimental data.
• NBO and AIM analysis were performed in order to evaluate the stability of the molecule.
• HOMO and LUMO analysis were used to evaluate some molecular properties.
• DSC measurements were performed to evaluate the thermodynamic parameters associated to different transitions.

The experimental and theoretical study on the molecular structure and a new vibrational analysis of 4-(Dimethylamino) Benzaldehyde (DMABA) is presented. The IR and Raman spectra were recorded in solid state. Optimized geometry, vibrational frequencies and various thermodynamic parameters of the title compound were calculated using DFT methods and are in agreement with the experimental values. A detailed interpretation of the IR and Raman spectra of the title compound were reported. The stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using NBO analysis and AIM approach. The HOMO and LUMO analysis were used to determine the charge transfer within the molecule and some molecular properties such as ionization potential, electron affinity, electronegativity, chemical potential, hardness, softness and global electrophilicity index. The TD-DFT approach was applied to assign the electronic transitions observed in the UV–visible spectrum measured experimentally. Molecular electrostatic potential map was performed by the DFT method. According to DSC measurements, the substance presents a melting point of 72.34 °C and decomposes at temperatures higher than 193 °C.

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