c1ccc(-c2cc(-c3nnc4n3N=C(c3ccc5ccccc5c3)CS4)n[nH]2)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?