O=C(NCCCO)/C(=C/c1ccc(-c2cccc([N+](=O)[O-])c2)o1)NC(=O)c1ccccc1
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?