Cc1cc2nc(C3CCN(C(S)=NCC(C)C)CC3)[nH]c2cc1C.O=C(O)C(=O)O
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?