ERROR opening https://cactus.nci.nih.gov/chemical/structure/NC%28%3DO%29N%5BN%2B%5D%28%5BO-%5D%29%3DO/file?format=sdf&get3d=True  -- NC%28%3DO%29N%5BN%2B%5D%28%5BO-%5D%29%3DO could not be loaded.