Oc1ccc(C2C(c3ccccc3)=NN=C(c3ccc(Cl)cc3)N2O)c(O)c1
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?