O=C(CSc1nnnn1-c1ccc2c(c1)OCCO2)Nc1nc2c(s1)CCCC2
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?