O=C(CNc1cccc(Br)c1)Nc1ccc(S(=O)(=O)N2CCCCC2)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?