COc1cc(NC(=O)c2cc([N+](=O)[O-])ccc2NC(=O)CNC2CCCCC2)cc(OC)c1
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?