Cc1nnc2sc(-c3ccc(NC(=O)c4ccc(-c5ccc(Cl)cc5Cl)o4)cc3)nn12
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?