COc1ccc(CCNC(=O)CSc2n[nH]c3c4cc(F)ccc4nc-3n2)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?