O=C(Nc1cccc(-c2nc3ccccc3[nH]2)c1)c1ccc(C(=O)Nc2cccc(-c3nc4ccccc4[nH]3)c2)cc1
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?