COc1ccc(OC)c2sc(NC(=O)c3ccc(S(=O)(=O)N4CCOCC4)cc3)nc12
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?