CCN1CCc2c(sc(NC(=O)c3ccc(C(=O)c4ccccc4)cc3)c2C(N)=O)C1.Cl
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?