O=C1/C(=C/c2ccc(Oc3ccccc3)cc2)N=C(c2ccccc2)N1c1ccc(S(=O)(=O)Nc2nccs2)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?