COc1cccc(C(=O)NN2C(=S)N(c3ccccc3)C(=O)C2CC(N)=O)c1
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?