O=C(N/N=C/c1c[nH]c2ccccc12)c1cc(-c2ccc(-c3ccccc3)cc2)[nH]n1
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?