COc1ccc2c(c1)C1=C(CC2)C(c2ccc(C)cc2)NC(S)=N1
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?