COc1ccc(OC)c(-c2csc(NC(=O)Cc3cc(OC)c(OC)c(OC)c3)n2)c1
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?