COc1ccc(S(=O)(=O)Nc2cccc(-c3ccc(N4CCCC4)nn3)c2)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?