O=C(O)c1ccccc1/N=N\c1c(O)c(S(=O)(=O)O)cc2cc(S(=O)(=O)[O-])ccc12.[Na+]
Molecules with a polar surface area of greater than 140 angstroms squared (Å2) tend to be poor at permeating cell membranes. What's the psa of this molecule?