[O-][S+]1[C@@H](c2ccccc2)c2c(-c3ccccc3)sc(-c3ccccc3)c2[C@H]1c1ccccc1
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?