ERROR opening https://cactus.nci.nih.gov/chemical/structure/O%3DC%28O%29C%28NC%28%3DO%29CCN%29Cc1cncn1/file?format=sdf&get3d=True  -- O%3DC%28O%29C%28NC%28%3DO%29CCN%29Cc1cncn1 could not be loaded.