O=S(=O)(NC(c1ccccc1)(c1cc2ccccc2[nH]1)c1cc2ccccc2n1S(=O)(=O)c1ccccc1)c1ccccc1
The negative base-10 logarithmic of dissociation constant (pka) for an acid is a direct consequence of the underlying thermodynamics of the dissociation reaction; the pKa value is directly proportional to the standard Gibbs free energy change for the reaction. What is the pka value of this molecule?