COC(=O)C(Cc1nc2ccccc2nc1O)C(=O)C(=O)Nc1ccc([N+](=O)[O-])cc1[N+](=O)[O-]
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?