COc1ccc(C(=O)N/C(=C\c2cccc3ccccc23)C(=O)NCCc2c[nH]c3ccccc23)cc1OC
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?