COc1cccc(CNC(=O)c2ccc3c(=O)n4nc(Nc5ccccc5)sc4nc3c2)c1
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?