ERROR opening https://cactus.nci.nih.gov/chemical/structure/O%3DC1C%28O%29%3DC%28N%29NC%28N%29%3DN1/file?format=sdf&get3d=True  -- O%3DC1C%28O%29%3DC%28N%29NC%28N%29%3DN1 could not be loaded.