Br.COc1ccc(-c2cs/c(=N\c3ccccc3)n2CC(O)c2ccc([N+](=O)[O-])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?