Complexation thermodynamics of UO22+/diglycolamide complex in a room temperature ionic liquid: A study by optical spectroscopy and microcalorimetry

Complexation thermodynamics of UO22+ and a series N,N,N’,N’-tetraalkyl diglycolamide (TRDGA) ligands having alkyl chains –CH3 to –C6H13 were investigated in an ionic liquid (IL). The complexation constant for UO22+/DGA complex increased linearly with increasing chain length DGA from tetramethyl (logβ1 = 4.52, logβ2 8.01) tetrahexyl 5.62, 10.3). There two types species recorded the calorimetric titration all four ligands, one endothermic complexation, other exothermic. This observation was contrast those observed aqueous medium, where both stepwise enthalpies endothermic. structural feature indicated formation [UO2L2]2+ type without water or Tf2N− anion primary coordination sphere uranyl cation.