Nc1nc(SCCC/C=C/I)nc2c1ncn2C1OC(COP(=O)(O)O)C(O)C1O
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?