C/C=C(\C)C(=O)NCCN1C2=NC[C@H](Cc3ccccc3)N2C[C@H]1Cc1ccc(O)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?