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