S=C(Nc1ccccc1)N(/N=C/C=C/c1ccccc1)c1nnc(-c2ccccc2)c(-c2ccccc2)n1
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?