Conformational and microwave dielectric relaxation studies of hydrogen bonded polar binary mixtures of propionaldehyde with isopropyl amine

Abstract

The dielectric behaviour of the polar liquids like propionaldehyde, isopropyl amine and their equimolar binary mixture in nonpolar solvent benzene is studied in the microwave frequency range using the cavity perturbation technique at 6.218 GHz (J band), 9.880 GHz (X band), 16.331 GHz (P band) and 24.951 GHz (K band). Hamiltonian quantum mechanical calculations such as AM1, PM3, and MNDO optimized converged geometry operation is performed by using Argus lab chemical modelling software 2004 for both pure and binary systems of propionaldehyde and isopropyl amine. Dipole moments of the binary mixtures are calculated from the dielectric data using Higasi's method and compared with the theoretical results. Conformational analysis of the formation of a hydrogen bond between the propionaldehyde and isopropyl amine is supported by FT-IR, proton NMR spectra and molecular polarizability calculations. The average relaxation times are calculated from their respective Cole–Cole plots.

Keywords:

• complex permittivity
• dipole moment
• relaxation time
• Hamiltonian calculations