O=C(c1cc(C(=O)NCCc2ccccc2)c(=O)n(CCc2ccccc2)c1)c1cc(Cl)ccc1O
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?