ERROR opening https://cactus.nci.nih.gov/chemical/structure/CC1%3DC%28N%3DC%28C%28%3DN1%29C%29N%28C%29C%29C/file?format=sdf&get3d=True  -- CC1%3DC%28N%3DC%28C%28%3DN1%29C%29N%28C%29C%29C could not be loaded.