O=C(COc1ccc(OCC(=O)N2C(=O)CS/C2=N\c2ccccc2)cc1)N1C(=O)CS/C1=N\c1ccccc1
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?