O=C(CSc1nnc(NC(=O)C2CC(=O)N(c3ccccc3)C2)s1)NC1CCCC1
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?