O=C(NC1CCN(Cc2ccccc2)CC1)c1ccc(Oc2cc(Cl)cc(Cl)c2)o1
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?