COc1ccc(NC(=O)CN2CCN(CC(=O)Nc3ccccc3Cl)CC2)c(OC)c1
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?