O=C(CC(=O)Nc1ccccc1Cl)NNC(c1cc(/N=N/c2ccc(Br)cc2)ccc1O)P(O)O
The negative base-10 logarithmic of dissociation constant (pKa) for an acid is a direct consequence of the underlying thermodynamics of the dissociation reaction; the negative pKa value is directly proportional to the standard Gibbs free energy change for the reaction. What is the negative pKa value of this molecule?