COc1cccc(N2CCN(c3ccc4nnc(CCC(=O)Nc5ccccn5)n4n3)CC2)c1
The negative base-10 logarithmic of dissociation constant (pka) for an acid is a direct consequence of the underlying thermodynamics of the dissociation reaction; the pKa value is directly proportional to the standard Gibbs free energy change for the reaction. What is the pka value of this molecule?