An insight of novel eutectic mixture between thiazolidine‐2,4‐dione and zinc chloride: Temperature‐dependent density functional theory approach

Abstract

AbstractDeep eutectic solvents (DESs) are the mixture of a hydrogen bond donor (HBD) and a hydrogen bond acceptor (HBA) in a particular equivalent ratio. They gained popularity because of low melting point and green (non‐toxic) in nature. DESs showed promising ability as solvents and found to be better than traditional organic solvents and ionic liquids. They are being explored solvents in organic synthesis, substance dissolution, corrosion inhibition, biofuel generation, SO2/CO2 absorption, and extraction. In the present work, thioazolidine‐2,4‐dione (T) is taken as hydrogen bond donor, and zinc chloride (Z) is taken as hydrogen bond acceptor. Nine DESs are created using T and Z having different equivalent ratio. Further, they were studied using density functional theory (DFT) approach in gaseous state at different temperatures. T4Z1 found to most soluble in water as the dipole moment is maximum. Free energy of T1Z4 found to be least so may be most stable among all. Further, on changing the temperature from 298 to 323 K and then to 348 K, thermodynamic parameters are determined. Further, the change in free energy for the formation of the DESs are calculated in Hartree per particle as well in kcal/mol. At 298 K, the change in free energy for the formation of T2Z3 is minimum and indicates it feasibility or spontaneity at this temperature. But at temperature of 323 K, T1Z4 and T2Z3 are found to be same. Further, on increasing temperature to 348 K, the change in free energy for T1Z4 and T2Z3 is same and minimum. It means on changing the temperature, the spontaneity for the formation of DES changes. Based on the method of Jakob et al., it can be seen that the temperature changes with the change in composition, that is, the ratio of HBD and HBA. The composition of HBD and HBA is 1:2 and is called deep eutectic mixture as the melting temperature observed is least. There is not a complete agreement between the results obtained by DFT calculations and Jakob et al method.