COC(=O)CN1C(=O)C2(C(C#N)=C(N)Oc3[nH]nc(-c4cccs4)c32)c2ccccc21
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?