O=[N+]([O-])c1ccc(C(c2sc3nc(-c4ccco4)nn3c2O)N2CCN(Cc3ccccc3)CC2)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?