COc1cc2c(cc1O)[C@H](Cc1ccc(Oc3cc(C[C@@H]4NCCc5cc(OC)c(O)cc54)ccc3O)cc1)NCC2
The negative base-10 logarithmic of dissociation constant (pka) for an acid is a direct consequence of the underlying thermodynamics of the dissociation reaction; the pKa value is directly proportional to the standard Gibbs free energy change for the reaction. What is the pka value of this molecule?