COc1cc(C(=O)N2CCCCC2c2cc(C(=O)Nc3ccccc3Cl)no2)cc(OC)c1C
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?