COc1ccc(-c2nc(C(N)=O)c3c(n2)n(-c2ccccc2OC)c(=O)n3C)c(OC)c1
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?