in your element Rounding up lutetium Lars Öhrström suspects that as time goes by, we may see more of lutetium — the last of the lanthanoids.

e’ll always have Paris” Rick says motexafin (based on the ‘texaphyrins’), a “ to Ilsa in their final goodbye on sub-class of porphyrin-like macrocycles Wthe foggy airstrip of Casablanca with five instead of four nitrogen atoms in in the eponymous film. However, the an approximately planar ring. Motexafin question among chemists about the element lutetium, which features Lu3+ and two lutetium, named after Lutetia, as the French acetate counter-ions coordinated on either capital was known in Roman times, is not so side of the macrocycle, is potentially a good much about having it (it is more abundant photosensitizer in dynamic phototherapy

than silver in the Earth’s crust), but rather and has been going through phase I trials where to place it on the map. against prostate cancer2. With its valence electron configuration Uses of the naturally occurring element [Xe]4f 146s25d1, element 71 seems to belong are otherwise scarce, but its isotope Lu-177 is to group 3, but we often see it placed at successfully used in experimental and clinical BRITTA LANGEN, BRITTA SWEDEN UNIVERSITY OF GOTHENBURG, the very end of the lanthanoid series. Its treatments against some severe cancers by downstairs neighbour lawrencium, for which Illustration of a radiolabelled somatostatin hooking it up to a tetraazacyclododecane- experimental data are much more difficult to analogue built using PyMOL (https://pymol.org) tetraacetate (DOTA) ligand grafted to obtain, is in the same ambiguous situation. So with a DOTA derivative (PDB: 1NC26, shown octreotate, a small peptide (pictured). DOTA which elements should come below scandium in black) enclosing lutetium (in lilac), and acts as a seven- or eight-coordinating chelator and yttrium — lutetium and lawrencium, or Tyr 3–octreotate (PDB: 1YL87); the part of whereas octreotate binds to receptors on lanthanum and actinium? octreotate that binds to the receptor is shown in the surfaces of a number of neuroendocrine Many periodic tables — including the turquoise. PDB, protein data bank. tumour cells, thus directing the ionizing one presented by the International Union of radiation of the lutetium isotope into the Pure and Applied Chemistry (IUPAC) — are tumour and killing it3,4. a bit vague on this point, and the question Historic Chemical Landmark dedicated to Lutetium is also used, together with of group-3 membership is currently under him at the University of New Hampshire. hafnium, in geological radioactive dating, thorough investigation by an IUPAC project1. The International Atomic Weights and trace amounts can be analysed by Meanwhile, the chemical closeness of the Commission under its chair Frank Clarke neutron activation. This was recently used in group-3 and 4f blocks are widely recognized settled the dispute in 1909. The discovery quantifying rare earths, including lutetium, and reflected through collective names credit was attributed to Urbain and his in the sediments of the Bou Regreg River in approved by the IUPAC: the ‘lanthanoids’ suggested name — lutecium, later to be spelled Morocco — not far from Casablanca5. Here’s designate the 15 elements from lanthanum to lutetium — was adopted over Welsbach’s looking at Lu, kid! ❐ lutetium, and the ‘rare-earth metals’ include cassiopeium. Oddly, this was not the end of those 15 as well as the unambiguous members element 71’s role in the naming game. In 2009, LARS ÖHRSTRÖM is the author of ‘The of group 3, scandium and yttrium. the name copernicium was proposed for the Last Alchemist in Paris & Other Curious Tales In any case, lutetium was isolated new element 112, but its suggested symbol Cp from Chemistry’, and is in the Department independently by three chemists in 1907, was rejected by IUPAC because it had already of Chemistry and Chemical Engineering, from samples composed of mainly an oxide been used for cassiopeium — which, although Chalmers University of Technology, of ytterbium, one of the later lanthanoids — not official, was used in the German-speaking SE-412 96 Gothenburg, Sweden. so it seems fitting for lutetium to also be world for a long time; copernicium instead got e-mail: [email protected] considered part of this gang. There appears the symbol Cn. Twitter: @Larsohrstrom to have been a heated argument over Lutetium is mined together with the References priority between two of the discoverers, other rare-earth metals from oxides, but 1. Ball, P. The group 3 dilemma. Chemistry World (21 April 2017); Georges Urbain and Carl Auer von Welsbach, is much less abundant, with an average http://go.nature.com/2DDblBV from France and Austria, respectively. The yield that is in the range 0.01–1.00%. Water 2. Gheewala, T., Skwor, T. & Munirathinam, G. Oncotarget 3+ 8, 30524–30538 (2017). third — uncharacteristically for the field — solutions will contain colourless Lu ions, 3. Spetz, J. et al. BMC Cancer 17, 528–539 (2017). kept a low profile, though the US chemist the only stable oxidation state, with seven 4. Swärd C. et al. World J. Surgery 34, 1368–1372 (2010). Charles ‘King’ James now has a National to nine water molecules coordinated. This 5. Bounouira, H., Choukri, A., Elmoursli, R. C., Hakam, O. K. & means that to be useful, coordinating Chakiri, S. J. Appl. Sci. Environ. Manage. 11, 57–60 (2007). 6. Corneillie T. M., Fisher A. J. & Meares C. F. J. Am. Chem. Soc. ligands need to support high coordination 125, 15039–15048 (2003). numbers, and that is exactly the case for 7. Spyroulias, G. A. et al. Med. Chem. 1, 487–499 (2005). Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra 372 NATURE CHEMISTRY | VOL 10 | MARCH 2018 | www.nature.com/naturechemistry ©2018 Mac millan Publishers Li mited, part of Spri nger Nature. All ri ghts reserved.