ERROR opening https://cactus.nci.nih.gov/chemical/structure/CC%3D1C%3D2C%28NC%28C%29%28C%29C1%29%3DCC%3DCC2/file?format=sdf&get3d=True -- CC%3D1C%3D2C%28NC%28C%29%28C%29C1%29%3DCC%3DCC2 could not be loaded.