O=C(Cn1[nH]c(=O)c2ccccc2c1=O)Nc1cccc(-c2nnc3n2CCCCC3)c1
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?