ERROR opening https://cactus.nci.nih.gov/chemical/structure/CC%28C%29%28C%29NCC%28COC1%3DNSN%3DC1N2CCOCC2%29O/file?format=sdf&get3d=True  -- CC%28C%29%28C%29NCC%28COC1%3DNSN%3DC1N2CCOCC2%29O could not be loaded.