CCCCn1cc[n+](C2=C([N-]S(=O)(=O)c3ccc(Cl)cc3)C(=O)c3ccccc3C2=O)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?