COc1ccc2[nH]c(C(=O)N3CC(CCl)c4ccc([N+](=O)[O-])cc43)cc2c1
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?