Extraction and DFT Study on the Complexation of Zn2+ with Beauvericin

From extraction experiments and.-activity measurements, the exchange extraction constant corresponding to the equilibrium Zn2+(aq) + 1 center dot Sr2+(nb) double left right arrow 1 center dot Zn2+(nb) + Sr2+(aq) taking place in the two-phase water-nitrobenzene system (1 = beauvericin; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K-ex (Zn2+, 1 center dot Sr2+) = -0.3 +/- 0.1. Further, the stability constant of the beauvericin - zinc complex (abbrev. 1 center dot Zn2+) in nitrobenzene saturated with water was calculated for a temperature of 25 degrees C: log beta(nb) (1 center dot Zn2+) = 9.1 +/- 0.2. Finally, by using quantum mechanical DFT calculations, the most probable structure of the 1 center dot Zn2+ complex species was predicted.