N/N=C(\c1nc2ccc([N+](=O)[O-])cc2nc1O)C(O)c1ccc(Cl)c(Cl)c1
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?