O=C1NC(c2ccc(-c3ccccc3[N+](=O)[O-])o2)C(C(=O)c2ccc(Cl)cc2)C(O)(C(F)(F)F)N1
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?