O=C(NC(C(=O)N/N=C/c1ccccc1)c1nnc(O)c2ccccc12)c1ccccc1
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?