ERROR opening https://cactus.nci.nih.gov/chemical/structure/C1%3DCC%3DC%28C%3DC1%29N%28N%3DO%29O-.NH4%20/file?format=sdf&get3d=True  -- C1%3DCC%3DC%28C%3DC1%29N%28N%3DO%29O-.NH4%20 could not be loaded.