O=C(NN1C(=O)C2C(c3ccccc3)C=CC(c3ccccc3)C2C1=O)c1ccccc1
An acid's negative base-10 logarithmic dissociation constant (pKa) follows directly from its underlying thermodynamics; the negative pKa is directly proportional to its standard Gibbs free energy change. What is the negative pKa value of this molecule?