O=C1C[C@H](CCC(=O)OCc2ccccc2)NC(=O)C[C@H](CCC(=O)OCc2ccccc2)NC(=O)C[C@H](CCC(=O)OCc2ccccc2)N1
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?