COc1ccc(NC(=O)c2c(NC(=O)CNCc3ccco3)sc3c2CCC3)c(OC)c1
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?