O=[N+]([O-])c1ccc(NN=C2c3ccccc3Cc3ccccc32)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?