COc1ccc(NC(=O)c2sc3nc4c(c(-c5ccc(OC)cc5)c3c2N)C(=O)CC(C)(C)C4)cc1
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?