O=C(NNS(=O)(=O)c1ccc([N+](=O)[O-])cc1)c1cnn(-c2ccccc2)c1-n1cccc1
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?