COC(=O)c1ccc(Cn2nnc3c(O)nc(C4CCCN(S(=O)(=O)c5ccccc5Cl)C4)nc32)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?