Life and Death with Nitrogen

in your element Life and death with nitrogen Although first known among chemists for its noxious or lifeless character, nitrogen was later revealed to be involved in many life, and death, processes. Michael Tarselli ponders on this unforeseen characteristic. oticing that nitrogen gas (N2) supported of N2 with H2) was developed around the neither combustion nor life, many First World War; before then, explosives were Nscientific luminaries of the eighteenth produced from concentrated nitrates found in century — Scheele, Priestley, Lavoisier… guano (bird droppings). Nitrogen’s penchant — referred to nitrogen as ‘noxious air’, or for explosion extends to TNT, ammonium even ‘lifeless’. Yet element 7 has boasted an nitrate, nitroglycerin and nitrogen triiodide unparalleled career in the ensuing 300 years, — which decomposes at a feather’s touch, participating in organic catalysis, bombs, making for a thrilling demonstration tool. power generation, food contamination, and Despite knowing that compounds with high the elucidation of DNA’s structure. nitrogen-to-carbon ratios, like azides and Nitrogen heads up Group 15, the tetrazoles, are potentially explosive, chemists appropriately named pnictides (from the cannot resist. Recently, Klapötke and co- Greek pnigein, ‘to choke’), which includes workers synthesized a compound with a other life-and-death players: arsenic, a 10-nitrogen-atom chain, which was barely poison also found in drugs, and phosphorus, stable enough to allow analysis and shattered toxic yet present in the backbone of DNA. several pieces of lab glassware5. These elements have three unpaired electrons The life-or-death duality is observed in their p valence shell, and may also bond © ALEX WING throughout medical and pharmaceutical through their s electrons, so they ideally want history. Nitrogen is often associated with 3 to 5 bonds. In its elemental state, nitrogen designed ‘extended’ nucleobases2, which can stench and death: we can smell putrescine forms the diatomic gas N2 that makes up replicate and pair up much like normal DNA. and cadaverine, two volatile amines emitted more than 70% of the air we breathe. Newborn babies owe a lot to another from dead tissues, in vanishingly small Nitrogen’s penchant for forming three nitrogenated compound, folic acid amounts. Cyanide, a poison known since covalent bonds while keeping a lone pair (vitamin B9), critical to proper foetal antiquity, contains a C≡N moiety. Feeling ‘open for business’ leads to numerous development during pregnancy. Melamine faint? ‘Smelling salts’ that bring a person back catalytic and biochemical applications. Much (C3H6N6), however, recently made darker to consciousness often consist of ammonium of the burgeoning field of organocatalysis1 headlines. In food, nitrogen normally comes carbonate. Aniline dyes, originally thought relies on small species derived from two from proteins, and nitrogen analysis thus useless waste from coal tars, exhibited potent nitrogenous precursors: proline, an amino serves to measure protein content. Used biological activity, giving rise to the modern acid, and urea, the first organic molecule to dope infant formula and pet food to pharmaceutical industry6. prepared synthetically (Friedrich Wöhler, artificially inflate their apparent protein Given its tendency to corrupt, catalyse, 1828). In nature, porphyrins — polypyrrole content, melamine made both people and nurture, or destroy, nitrogen has proved its macrocycles present in haem enzymes and pets ill. lifeless reputation dead wrong. ❐ chlorophyll — host transition metals to Nitrogen plays a pivotal role in the perform basic life functions: photosynthesis, development of renewable energies. Nocera’s This essay was selected as a winning entry in our oxygen transport and destruction of ‘hangman’ assemblies3, which generate writing competition, see http://go.nature.com/oi187X toxins in the blood. Several heavy metals oxygen and hydrogen gas from water MICHAEL A. TARSELLI is a Principal Scientist (molybdenum, vanadium, iron), allow soil splitting to power fuel cells, feature an at Biomedisyn, 11 Research Drive, Suite 3, bacteria in the roots of legumes to fix N into octafluoro–corrole backbone, which binds 2 Woodbridge, Connecticut 06525, USA. usable plant metabolites. cobalt through coordination to four nitrogen e-mail: [email protected] Life is intricately linked to nitrogen, found atoms. One possible way to safely transport in every DNA nucleobase. Isotopic labelling hydrogen fuel is through ammonia borane References 15 4 with heavy isotope N allowed Meselson and (H2N–BH3) complexes. New solar cells 1. Jacobsen, E. N. & MacMillan, D. W. C. Proc. Natl Acad. Sci. 107, Stahl to verify that a single strand of DNA also rely on dyes containing metal–nitrogen 20618–20619 (2010). 2. Liu, H. et al. Science 302, 868–871 (2003). could template its own replication. Chemists bonds to catch ambient light, making for 3. Dogutan, D. K., McGuire, R. Jr & Nocera, D. G. J. Am. Chem. Soc. interested in tinkering with life’s codes have flexible, highly efficient, cost-effective devices. 133, 9178–9180 (2011). Entire wars have turned on nitrogen 4. Daeneke, T. et al. Nature Chem. 3, 211–215 (2011). 5. Klapötke, T. M. & Piercey, D. G. Inorg. Chem. 50, 2732–2734 (2011). compounds: the Haber–Bosch process 6. Garfield, S. Mauve: How One Man Invented a Colour that (ammonia production by catalytic reaction Changed the World (W. N. Norton, 2001). Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr 686 NATURE CHEMISTRY | VOL 4 | AUGUST 2012 | www.nature.com/naturechemistry © 2012 Macmillan Publishers Limited. All rights reserved.

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