O=[N+]([O-])c1ccccc1/C=C/C=N/Nc1ccc(S(=O)(=O)Nc2ccc(Cl)cc2)cc1[N+](=O)[O-]
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?