N#CC(C(=O)/C(=N/Nc1nc(S)nn1N)C(C#N)c1ccccc1)c1ccccc1
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?