O=C(CCC1N=C2c3ccccc3N=C(SCc3ccc(F)cc3)N2C1=O)NCCc1ccccc1
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?