ERROR opening https://cactus.nci.nih.gov/chemical/structure/O%3DC1N%28/N%3DC%28%5CC1%29C%29c2ccccc2/file?format=sdf&get3d=True  -- O%3DC1N%28/N%3DC%28%5CC1%29C%29c2ccccc2 could not be loaded.