Quantum chemical calculations for the norbadione A complexes with Cs, K, and Na in gas and aqueous phases

Suno, Hiroya  ; Machida, Masahiko  

We perform quantum chemical calculations for the Cs, K, and Na complexes of norbadione A (NBA), a pigment molecule in mushrooms known to accumulate Cs. A numerical two-step approach, by Ota , is employed to examine its alkali-metal-cation complexation selectivity in aqueous solutions. Applying it to the neutral, di- and tetra-deprotonated NBAs, we confirm that the complexation selectivity on Cs emerges only in high pHs, in which the di-protonated NBA dominates, in agreement with experimental results. This is the first demonstration of the approach for a biological molecule whose selectivity is known to be anomalous.