O=C(Nc1ccc2ccccc2c1)N1C[C@@H]2C[C@H](C1)Cn1c2cccc1=O
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?