O=C(Cn1cnc2cc([N+](=O)[O-])ccc2c1=O)Nc1ccc2c(c1)CCC2
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?