ERROR opening https://cactus.nci.nih.gov/chemical/structure/CN1C%3DC2C%28C%3DCC%3DC2NC2%3DNCCN2%29%3DN1/file?format=sdf&get3d=True  -- CN1C%3DC2C%28C%3DCC%3DC2NC2%3DNCCN2%29%3DN1 could not be loaded.