COc1ccc(NC(=O)CSc2ncc3c(n2)-c2ccccc2N(C)S3(=O)=O)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?