ERROR opening https://cactus.nci.nih.gov/chemical/structure/O%3DC2NC%28%3DO%29NC2%28c1ccccc1%29c3ccccc3/file?format=sdf&get3d=True  -- O%3DC2NC%28%3DO%29NC2%28c1ccccc1%29c3ccccc3 could not be loaded.