O=C(Cc1csc(-c2cccc(Cl)c2)n1)Nc1cccc(S(=O)(=O)NC2=NCCC2)c1
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?