COc1cccc(NC(=O)CC(=O)N2N=C(N(CCC#N)c3ccc(Cl)cc3)CC2c2ccccc2)c1
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?