Thermal and magnetic properties and vibrational analysis of 4-(dimethylamino) pyridine: A quantum chemical approach

• The FT-IR and FT-Raman spectra of 4-(dimethylamino) pyridine were recorded and analyzed.
• The complete vibrational assignments and spectroscopic analysis were made.
• The HOMO, LUMO energy gap were theoretically predicted.
• Temperature dependence thermodynamic parameters and magnetic properties have been analyzed.
• The magnetic susceptibility for various temperatures are predicted.

The FT-IR and FT-Raman spectra of 4-(dimethylamino) pyridine (4DMAP) have been recorded in the region 4000–500 cm−1and 3500–100 cm−1. Quantum chemical calculations of energy, geometry and vibrational wavenumbers of 4DMAP were carried out by using ab initio HF and density functional theory (DFT/B3LYP) with complete relaxation in the potential energy surface using 6-311++G(d,p) basis set. The harmonic vibrational wavenumbers were calculated and the scaled wavenumbers have been compared with the experimental FT-IR and FT-Raman spectra. The quantum chemical parameters have been computed from the HOMO–LUMO energy values. Temperature dependence thermodynamic parameters and magnetic properties of the title compound have been analyzed. Using NBO analysis the stability of the molecule arising from hyper-conjugative interactions, charge delocalization has been analyzed. The first-order hyper-polarizability (β) values of the title molecule were computed by B3LYP method. Finally the theoretically spectrograms for FT-IR and FT-Raman spectra of the title molecule have been constructed which show good agreement with recorded spectra.

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