O=C(O)c1ccc(N=N/C(=N\Nc2ccc(C(=O)O)cc2)c2ccccc2)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?