ERROR opening https://cactus.nci.nih.gov/chemical/structure/CCNC%28CC1%3DCC2%3DC%28C%3DCO2%29C%3DC1%29C/file?format=sdf&get3d=True -- CCNC%28CC1%3DCC2%3DC%28C%3DCO2%29C%3DC1%29C could not be loaded.