O=C(c1ccccc1)N1CCN(C2c3cccc4cccc(c34)C2NS(=O)(=O)c2ccccc2)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?