ERROR opening https://cactus.nci.nih.gov/chemical/structure/OC1NC2%3DNC%28%3DO%29N%3DC2C%28%3DO%29N1/file?format=sdf&get3d=True  -- OC1NC2%3DNC%28%3DO%29N%3DC2C%28%3DO%29N1 could not be loaded.