COc1cccc(-c2nc(SCC(=O)Nc3ccc4c(c3)OCCO4)c(-c3ccccc3)[nH]2)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?