COc1ccc(CC(=O)Nc2sc3c(c2C(=O)Nc2ccc(C)cc2)CCCCC3)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?