CC1C(c2cccs2)=[N+]([O-])C(C)(C(=O)c2ccc(Cl)cc2)N1O
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?