O=S(=O)(O)c1cc(O)c2c(/N=N/c3ccc(Nc4ccccc4)c4c(S(=O)(=O)O)cccc34)cc(S(=O)(=O)O)cc2c1
An acid's negative base-10 logarithmic dissociation constant (pka) follows directly from its underlying thermodynamics; pKa is directly proportional to its standard Gibbs free energy change. What is the pka value of this molecule?