Fc1ccc(-[n+]2nc(Nc3ccccc3)sc2-c2c3ccccc3cc3ccccc23)cc1.[Cl-]
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?