CC[C@H](C)C1=C(O)[N@+]2([O-])Oc3ccc(-c4c(O)c(O)c(-c5ccc(O)cc5)c(OC(C)=O)c4OC(C)=O)cc3O[C@]2([C@@H](C)CC)C(=O)N1O
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?