High-frequency dielectric study on the hydrogen bonding interaction on aqueous Cyanoacetamide

Abstract

The Complex permittivity spectra ε∗(ω) of the mixtures of Cyanoacetamide (CYN) and water in the composition of different mole fractions were achieved in the frequency domain of 10 MHz to 50 GHz at temperatures 25, 20, 15, 10 and 5 °C using Time Domain Reflectometry (TDR) method. The observed values of dielectric spectra can be well defined with the Cole-Davidson relaxation model. The dielectric functions like static dielectric constant (ε0), relaxation time (τ) and Cole Davidson distribution parameter (β) were obtained and also used to determine and discuss the theoretical parameters such as effective Kirkwood Correlation factor (geff), excess dielectric constant ε0E and excess inverse relaxation time ((1/τ)E) to provide information on dipolar alignment and molecular rotation within the solution. Thermodynamic properties such as the free energy of activation (ΔF), the entropy of activation (ΔS∗) and the enthalpy of activation (ΔH∗) were obtained. The free energy of activation is found to be independent of temperature and the average value of free energy is calculated as, 14.28 kJ mol−1. The enthalpy of activation shows the endothermic nature of the reaction. FT-IR results were compared with the Molecular Dynamics (MD) simulation study confirms the formation of the heterogeneous hydrogen-bond network in the solution. The Average Water bridge residual time period and pair interaction energy between the unlike molecules have been determined, also it is confirmed that the higher value of excess permittivity indicates the maximum probability of Hydrogen-bond formation within the system.