O=C(Cc1cccc2ccccc12)NN1C(=O)/C(=C\c2cccnc2)SC1=S
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?