COc1ccc(NC(=O)Cn2ncc3c(C)n(Cc4cccc(Cl)c4)c(C)c3c2=O)cc1
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?