Cn1c(=O)c2cc(C(=O)NCCCN3CCN(c4cccc(Cl)c4)CC3)sc2c2ccccc21
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?