COc1ccc(C(CC(=O)Nc2ccc(C)c(C)c2)N2Cc3ccccc3C2=O)cc1OC
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?