O=C(NC1CC1)c1cccc2c1C(=O)c1ccc(N3CCC(Cc4ccccc4)CC3)cc1S2(=O)=O
An acid's negative base-10 logarithmic dissociation constant (pKa) follows directly from its underlying thermodynamics; the negative pKa is directly proportional to its standard Gibbs free energy change. What is the negative pKa value of this molecule?