ERROR opening https://cactus.nci.nih.gov/chemical/structure/CCN%28CC%29C1%3DNC%28%3DNN%29N%3DC%28N1%29N%28CC%29CC/file?format=sdf&get3d=True -- CCN%28CC%29C1%3DNC%28%3DNN%29N%3DC%28N1%29N%28CC%29CC could not be loaded.