Nc1ncnc2c1nc(Br)n2[C@@H]1O[C@H]2COP(=O)([O-])O[C@@H]2[C@H]1O.[Na+]
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?