O=c1[nH]c2cc([N+](=O)[O-])ccc2nc1/C(=N/Nc1ccccc1)C(O)c1ccccc1Cl
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?