COc1cc(/C=C(/C#N)c2nc(-c3cc4ccccc4oc3=O)cs2)ccc1O
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?