O=[N+]([O-])c1cc(/C=N/Nc2cc(N3CCOCC3)nc(N3CCOCC3)n2)cc2c1OCO2
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?