When we compare IsA and IA, we can see that IsA generally exhibits significantly lower binding free energies for bonding with other acids than is the case for IA. On the other hand, IA exhibits larger binding affinity with bases. The higher binding affinity for IsA has previously been observed, but the lower concentration of IsA than IA by 2 orders of magnitude 12 should be kept in mind. This is likely due to the pK a differences between IA and IsA, where IA is a significantly stronger acid than IsA.