ERROR opening https://cactus.nci.nih.gov/chemical/structure/CCC%28N%29CC1%3DCNC2%3DC%28C%29C%3DCC%3DC21/file?format=sdf&get3d=True  -- CCC%28N%29CC1%3DCNC2%3DC%28C%29C%3DCC%3DC21 could not be loaded.