O=C(Nc1ncc(S(=O)(=O)c2ccc([N+](=O)[O-])cc2)s1)c1cccc2ccccc12
An acid's negative base-10 logarithmic dissociation constant (pka) follows directly from its underlying thermodynamics; pKa is directly proportional to its standard Gibbs free energy change. What is the pka value of this molecule?