COC(=O)c1[nH]c2ccccc2c1/C=C1\C(=O)NC(=O)N(c2ccc(Br)cc2)C1=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?