CCN1CCCc2cc(CN(CCN3CCOCC3)C(S)=Nc3ccc(OC)c(Cl)c3)ccc21
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?