CO/C(O)=C1\C(C)=NC2=C(C(=O)CC(c3cccs3)C2)C1c1ccsc1
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?