Table 2. UB3LYP Binding Energy (ΔE) and Binding Gibbs Free Energy (ΔG) Calculated for the Linking Process of Compounds 5a, 5c, and 7 Analogs and the Heme Group in the 2:1 Molar Ratio^a.

	binding energies (kcal·mol–1)
compound	ΔE	ΔG
5a	–32.5	–7.4
5c	–42.8	–14.6
7	–56.9	–24.7

^aThe energies were calculated at 298 K and 1 atm with all values given in kcal·mol^–1