O=C1Oc2ccccc2C(=O)/C1=C/N1C(=O)/C(=C/c2ccc([N+](=O)[O-])cc2)SC1=S
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?