COc1ccc(-c2csc(NC(=O)CN3C(=O)NC4(CCCC4)C3=O)n2)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?