C=CCn1c(SCC(=O)Nc2ncc(Cc3ccc(C)c(Cl)c3)s2)nnc1-c1ccncc1
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?