O=C(Cc1csc(-c2nc(CC(=O)NNc3ccccc3)cs2)n1)NNc1ccccc1
An acid's negative base-10 logarithmic dissociation constant (pKa) follows directly from its underlying thermodynamics; the negative pKa is directly proportional to its standard Gibbs free energy change. What is the negative pKa value of this molecule?