Cn1c(CNC(=O)c2ccc(Cl)c(Cl)c2)nnc1SCC(=O)Nc1sc2c(c1C#N)CCCC2
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?