COc1ccccc1C1CC(c2cccc(NS(C)(=O)=O)c2)=NN1S(=O)(=O)c1ccccc1
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?