COc1cc(C2c3c(oc4cc(C)c(C)cc4c3=O)C(=O)N2CCCN2CCOCC2)ccc1O
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?