O=C(CSC1=NC(=O)C(c2ccccc2)C(=O)N1)Nc1ccccc1Cl
An acid's negative base-10 logarithmic dissociation constant (pKa) follows directly from its underlying thermodynamics; the negative pKa is directly proportional to its standard Gibbs free energy change. What is the negative pKa value of this molecule?