Scheme 2 . Sites considered in the BDE calculations for R,
RI and RII.
The proportion of neutral vs. charged species for molecules with
acid-base bahaviour is ruled by the pKa-pH relationship. Thus, acid
constants, expressed as pKa, were calculated for the subset of the most
promising R, RI and RII derivatives. A
fitted parameters approach (FPA) was used for that, because it was
already proven as reliable.160, 161 The calculated
data was compared with a reference set of molecules, previously used for
similar purposes.142 The computational protocol
described here is known as CADMA-Chem.140