COc1ccc(NC(=O)CSc2nc3c(c(=O)[nH]2)CN(Cc2ccccc2)CC3)cc1Cl
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?