O=S(=O)(O)c1ccc2c(/N=N\c3c(O)ccc4ccccc34)cccc2c1
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?