COc1cc(C2NC(S)=NC(c3ccccc3)=C2C(C)=O)cc(Cl)c1OCC(=O)O
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?