COc1ccc(-c2csc(NC(=O)CSC(C)C(=O)Nc3cc(C)on3)n2)cc1OC
An acid's negative base-10 logarithmic dissociation constant (pKa) follows directly from its underlying thermodynamics; the negative pKa is directly proportional to its standard Gibbs free energy change. What is the negative pKa value of this molecule?