COc1ccc(/C=C/C(=O)c2cc(C(=O)/C=C/c3ccc(OC)cc3)c(O)cc2O)cc1
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?