COc1ccc(-n2nc(C(=O)Nc3ccccc3OC)c3c4ccccc4n(C)c3c2=O)cc1Cl
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?