ERROR opening https://cactus.nci.nih.gov/chemical/structure/C1%3DNC2%3DNC%28%3DNC%28%3DC2N1%29N%29F/file?format=sdf&get3d=True  -- C1%3DNC2%3DNC%28%3DNC%28%3DC2N1%29N%29F could not be loaded.