COc1cc2c(cc1O)CCN[C@@]21CS[C@H]2c3c(OC(C)=O)c(C)c4c(c3C(COC1=O)N1C2C2NC(Cc3cc(C)c(OC)c(O)c32)[C@@H]1C#N)OCO4
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?