Thermodynamics Studies of a Novel Calix [4] Arene Derivative Designed to Bind Herbicides
Calix[4]arenes can be modified to produce materials which can capture and remove contaminants effectively such as herbicides. Chlorophenoxy acids have been selected out of groups of herbicides to carry out this investigation. A new calix[4]arene derivative containing mixed pendant arms in its lower rim, 5, 11, 17, 23- tetra- butyl- 25,27- bis (diethylamino) ethoxy- 26, 28- (bis-methoxyethoxy) calix [4] arene (L2), has been synthesized. 1H NMR investigations seems to indicate that the receptor L2 interacts with acid herbicides. Conductometric measurements were performed in acetonitrile at 298 K. In all cases, 1:2 (ligand: acid herbicide) complexes are formed. Standard thermodynamics parameters of complexation (log Ks, ΔHᵒ c, ΔSᵒ c, ΔGᵒ c) of L2 with herbicides in acetonitrile were determined using the Nano ITC (isothermal titration calorimetry). For all the systems investigated, the complexation process between these acid herbicides and the receptor L2 was enthalpically controlled.
