Nc1ncnc2c1ncn2[C@@H]1O[C@@H](COP(=O)(O)OP(=O)(O)OP(=O)(O)OP(=O)(O)OC[C@@H]2O[C@@H](n3cnc4c(N)ncnc43)[C@@H](O)[C@H]2O)[C@H](O)[C@@H]1O
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?