COc1ccc(Cl)cc1S(=O)(=O)N1CCN(C(=O)c2cc(-c3ccc(Br)cc3)n[nH]2)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?