COc1ccc(-c2nc(-c3cnccn3)n(C3OC(CO)C(O)C(O)C3O)n2)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?