COc1cc(C2CC(=O)Nc3c2c(C)nn3-c2nc(C)cc(C)n2)cc(OC)c1O
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?