O=C(CSCC(=O)N1CCN(c2ccccc2)CC1)Nc1nc(-c2ccc(Cl)s2)cs1
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?