COc1ccc(C2c3ccc(O)cc3Oc3ncn4nc(-c5ccncc5)nc4c32)cc1OC
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?