O=C(OCC1OC(n2nc(Cn3nnc(-c4cccnc4)n3)n(-c3cccc4ccccc34)c2=S)C(OC(=O)c2ccccc2)C1OC(=O)c1ccccc1)c1ccccc1
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?