COc1cc(/C=C2\S/C(=N/Nc3nc(-c4ccc(Br)cc4)cs3)NC2=O)cc(OC)c1OC
An acid's negative base-10 logarithmic dissociation constant (pka) follows directly from its underlying thermodynamics; pKa is directly proportional to its standard Gibbs free energy change. What is the pka value of this molecule?