O=C(Cn1nc(Cc2cccnc2)c2ccccc2c1=O)Nc1cccnc1Cl
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?