COc1ccc(C2c3ccc(O)cc3Oc3ncn4nc(-c5cccnc5)nc4c32)cc1OC
An acid's negative base-10 logarithmic dissociation constant (pKa) follows directly from its underlying thermodynamics; the negative pKa is directly proportional to its standard Gibbs free energy change. What is the negative pKa value of this molecule?