O=C(Nc1ccc(Cl)cc1)N1CCC(c2nc(-c3ccccc3Cl)no2)CC1
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?