Cc1c(C(=O)C/C(=N/NC(=O)C[N+](C)(C)C)C(=O)Nc2ccc(Cl)cc2)[n+]([O-])c2ccccc2[n+]1[O-].[Cl-]
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?