O=C(CC(=O)Nc1ccccc1)NNC(Sc1ccccc1)c1cc(/N=N/c2ccc(Br)cc2)ccc1O
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?