O=[N+]([O-])c1cc(C(F)(F)F)cc([N+](=O)[O-])c1Sc1n[nH]c(C(F)(F)F)n1
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?