O=C(Nc1cccn(Cc2c(Cl)cccc2Cl)c1=O)c1c(Cl)cccc1Cl
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?