O=C(c1ccccc1-c1ncc[nH]1)N1CCc2c([nH]c3ccccc23)C1c1ccccn1
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?