COc1cccc(NC(=O)c2sc3nc(C)c(C(=O)Nc4ccc(C)cc4C)c(-c4sccc4C)c3c2N)c1
An acid's negative base-10 logarithmic dissociation constant (pka) follows directly from its underlying thermodynamics; pKa is directly proportional to its standard Gibbs free energy change. What is the pka value of this molecule?