O=C1OCCN1C(=O)[C@H]1[C@H](c2ccc([N+](=O)[O-])cc2)C(c2cccc(Cl)c2)=NN1c1ccc(Br)cc1
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?