N#CC1=C(N)N2C(=O)/C(=C/c3ccccc3)SC2C(c2nc3ccccc3[nH]2)=C1c1ccccc1
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?