COc1ccc(NC(=O)CSC2=Nc3ccccc3C3=NC(CCC(=O)NCc4cccs4)C(=O)N23)cc1
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?