Nc1ccc(/N=N/c2ccc(/C=C/c3ccc(/N=N/c4ccc(N)c5ccc(S(=O)(=O)O)cc45)cc3S(=O)(=O)O)c(S(=O)(=O)O)c2)c2cc(S(=O)(=O)[O-])ccc12.[Na+]
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?