O=C(O)c1cc(-c2ccc(/C=C3\NC(=O)N(c4ccc(Cl)cc4)C3=O)o2)ccc1Cl
An acid's negative base-10 logarithmic dissociation constant (pKa) follows directly from its underlying thermodynamics; the negative pKa is directly proportional to its standard Gibbs free energy change. What is the negative pKa value of this molecule?