COc1cc(C(=O)Nc2ccc3nc(SCc4ccc(C)cc4)sc3c2)cc(OC)c1OC
An acid's negative base-10 logarithmic dissociation constant (pka) follows directly from its underlying thermodynamics; pKa is directly proportional to its standard Gibbs free energy change. What is the pka value of this molecule?