O=C(c1ccc2c(=O)n(Cc3ccco3)c(=S)[nH]c2c1)N1CCN(Cc2ccccc2)CC1
The negative base-10 logarithmic of dissociation constant (pka) for an acid is a direct consequence of the underlying thermodynamics of the dissociation reaction; the pKa value is directly proportional to the standard Gibbs free energy change for the reaction. What is the pka value of this molecule?