O=C(O)c1cc(S(=O)(=O)O)cc(Nc2c3ccccc3nc3ccccc23)c1O
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?