O=C(Nc1nc2c(ccc3onc(-c4ccccc4[N+](=O)[O-])c32)s1)C1CC1
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?