ERROR opening https://cactus.nci.nih.gov/chemical/structure/c21c%28cccc1%29%5BnH%5Dc3c2CC%28N%28C%29C%29CC3/file?format=sdf&get3d=True  -- c21c%28cccc1%29%5BnH%5Dc3c2CC%28N%28C%29C%29CC3 could not be loaded.