O=C(NCC(c1ccco1)N1CCCCC1)c1cccc(NS(=O)(=O)c2ccc(Br)cc2)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?