COc1ccc(OC)c(NC(=O)CCc2c(C)nc3c(-c4ccccc4)c(C)nn3c2C)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?