ERROR opening https://cactus.nci.nih.gov/chemical/structure/O%3DC%28N%28c1ccccc1%29CC%29N%28c2ccccc2%29CC/file?format=sdf&get3d=True  -- O%3DC%28N%28c1ccccc1%29CC%29N%28c2ccccc2%29CC could not be loaded.