CCOc1ccc(S(=O)(=O)[N-]c2nc3ccccc3nc2-[n+]2ccc(NC(=O)c3cccs3)cc2)cc1
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?