Nc1c([N+](=O)[O-])cc([N+](=O)[O-])c(-c2nnc(-c3c([N+](=O)[O-])cc([N+](=O)[O-])c(N)c3[N+](=O)[O-])s2)c1[N+](=O)[O-]
The negative base-10 logarithmic of dissociation constant (pka) for an acid is a direct consequence of the underlying thermodynamics of the dissociation reaction; the pKa value is directly proportional to the standard Gibbs free energy change for the reaction. What is the pka value of this molecule?