CC(=O)c1ccc(N2CCN(S(=O)(=O)c3ccc4c(c3)C(Cl)(Cl)C(=O)N4)CC2)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?