ERROR opening https://cactus.nci.nih.gov/chemical/structure/C%28%3DN%29%28N%29N.N%20%28%3DO%29%28O%29O-/file?format=sdf&get3d=True  -- C%28%3DN%29%28N%29N.N%20%28%3DO%29%28O%29O- could not be loaded.