O=C(CCS(=O)(=O)c1cc(Br)cc2c1N(C(=O)C1CC1)CC2)Nc1ccc(C(F)(F)F)cc1
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?