COc1ccc(NC(=O)C(=O)NNC(=O)c2sc(NNC(C)=O)nc2C)c([N+](=O)[O-])c1
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?