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

From extraction experiments and gamma-activity measurements, the extraction constant corresponding to the equilibrium Li+(aq)(+) 1 center dot Na+(nb) reversible arrow 1 center dot 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 K-ex (Li+, 1 center dot Na+) = 0.5 +/- 0.1. Further, the stability constant of the 1 center dot Li+ complex in nitrobenzene saturated with water was calculated for a temperature of 25 degrees C as log beta(nb) (1 center dot Li+)= 5.6 +/- 0.2. By using DFT calculations, the most probable structures of the non-hydrated 1 center dot Li+ and hydrated 1 center dot Li+center dot 3H(2)O complex species were predicted. (C) 2012 Elsevier B.V. All rights reserved.