COc1cccc(OCc2nnc3n2N=C(c2ccccc2)C(CC(=O)O)S3)c1
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?