COc1cc(C2SC(C)C(=O)N2c2ccc(-c3csc(NS(=O)(=O)c4ccc(Cl)c(OC)c4)n3)cc2)ccc1O
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?