COc1ccc(N2CCN(C(=O)CSc3ncccc3-c3nc4ccccc4[nH]3)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?