COc1ccc(OC)c(NC(=O)Cn2cnc3onc(-c4ccc(Cl)cc4)c3c2=O)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?