Complexation of the lithium cation with beauvericin: Experimental and DFT study

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Li+(aq) + 1·Na+(nb) ⇆ 1·Li+(nb) + Na+(aq) taking place in the two-phase water–nitrobenzene system (1 = beauvericin; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex (Li+, 1·Na+) = 0.5 ± 0.1. Further, the stability constant of the 1·Li+ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C as log βnb (1·Li+) = 5.6 ± 0.2. By using DFT calculations, the most probable structures of the non-hydrated 1·Li+ and hydrated 1·Li+·3H2O complex species were predicted.