COc1ccc2c(c1)O[C@H](c1ccc3c(c1)OCO3)[C@@H](OC(=O)Nc1ccc(C)c(Br)c1)C2=O
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?