O=C(CP(=O)(c1ccccc1)c1ccccc1)c1cccc(C(=O)CP(=O)(c2ccccc2)c2ccccc2)c1
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?