CCOc1ccc(CCN2C(=S)N([C@@H](CC(C)C)CN3CCCC3CN3C(=S)NC[C@@H]3CC(C)C)C[C@@H]2Cc2ccc(O)cc2)cc1
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?