O=C1CCCC2=C1C(c1ccc(O)c(Br)c1)C1=C(CCCC1=O)N2c1ccccc1
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?