ERROR opening https://cactus.nci.nih.gov/chemical/structure/CC%28C%29C1%3DCC%3DCC%3DC1OCC2%3DNCCN2/file?format=sdf&get3d=True  -- CC%28C%29C1%3DCC%3DCC%3DC1OCC2%3DNCCN2 could not be loaded.