. Author manuscript; available in PMC: 2009 Feb 8.

Published in final edited form as: J Mol Biol. 2007 Nov 28;376(1):13–22. doi: 10.1016/j.jmb.2007.11.059

Table 1.

Computed (DFT/B3LYP) structural and thermo-chemical properties of 6-fold ion-oxygen clusters in gas phase. Ion-oxygen distances Na⁺-O and K⁺-O are in Ångström units and ΔΔG_Na_⁺→_K_⁺ (ε = 1) are the free energy differences between the Na⁺ and K⁺ complexes in gas phase.

Ligand	Chemistry	ΔΔG_Na_⁺→_K_⁺ (ε = 1) (kcal/mol)	Na⁺-O	K⁺-O
Valinomycin	carbonyl	12.3	2.64	2.79
Formamide²⁰	carbonyl	20.6	2.42	2.80
Glycine Dipeptide²⁰	carbonyl	20.8	2.43	2.76
Water²⁰	hydroxyl	18.8	2.42	2.84
Methanol	hydroxyl	18.5	2.44	2.84