O=C(Nc1ccc(N2CCN(C(=O)c3ccco3)CC2)cc1)c1ccc([N+](=O)[O-])cc1Cl
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?