O=C(O)c1ccc(N2CC3CC(C2)c2cccc(=O)n2C3)c(NC(S)=Nc2ccc(Br)cc2)c1
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 pKa value is directly proportional to the standard Gibbs free energy change for the reaction. What is the pka value of this molecule?