COc1cc2cc(C(c3nnnn3C(C)(C)C)N3CCc4ccccc4C3)c(O)nc2cc1OC
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?