[C-]#[N+]C(=C\c1ccc(O)cc1)/C(=C/c1ccc(O)cc1)[N+]#[C-]
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?