Volume 543 Number 7647



News Features

News & Views

Tumour stem-cell surprises p.626

Stem-cell divisions are thought to be essential to tumour growth. Targeted removal of a specific stem-cell population reveals its role in tumour development and in the growth of tumours formed by cell migration to distant sites. See Article p.676

doi: 10.1038/543626a

Making iron glow p.627

An iron complex has been made that has a long-lived excited state and emits light at room temperature as a result of a charge-transfer process. This breakthrough might allow the production of cheap solar cells. See Letter p.695

doi: 10.1038/543627a

Forty years of cellular clues from worms p.628

The cell divisions that occur when a larva develops into an adult Caenorhabditis elegans worm were described in a cell-lineage map in 1977. The work has provided the foundation for many discoveries about developmental mechanisms.

doi: 10.1038/543628a

How to heal an ocean p.630

Marine protected areas are being implemented at an accelerating pace, and hold promise for restoring damaged ecosystems. But glaring shortfalls in staffing and funding often lead to suboptimal outcomes. See Article p.665

doi: 10.1038/nature21895

Auditory landscape on the cognitive map p.631

Subpopulations of neurons fire at specific geographical locations, providing a mental map of an animal's position in space. The finding that the circuitry can also support auditory maps sheds light on the neuronal structure of cognition. See Letter p.719

doi: 10.1038/543631a

Eating ourselves dry p.633

Do human consumption habits affect groundwater depletion as a result of international food trade? A global analysis indicates that they do, and shows which products and countries have the biggest impact. See Letter p.700

doi: 10.1038/543633a

The leukaemia epigenome targeted p.634

Modification of methyl groups attached to DNA alters gene expression, and mutations that deregulate this methylation are common in some leukaemias. Drugs that target aberrant methylation are emerging as promising therapeutics.

doi: 10.1038/543634a

Reckless orbiting in the Solar System p.635

Planets and most asteroids revolve around the Sun in the same direction. But an asteroid that shares Jupiter's orbit has been revolving in the opposite direction for about a million years. See Letter p.687

doi: 10.1038/543635a




A retrograde co-orbital asteroid of Jupiter p.687

Asteroid 2015 BZ509 is a retrograde co-orbital asteroid of the planet Jupiter, stably orbiting in a sense opposite to that of Jupiter’s orbit around the Sun for around a million years.

doi: 10.1038/nature22029

A low-spin Fe(iii) complex with 100-ps ligand-to-metal charge transfer photoluminescence p.695

Transition-metal complexes are used as photosensitizers, in light-emitting diodes, for biosensing and in photocatalysis. A key feature in these applications is excitation from the ground state to a charge-transfer state; the long charge-transfer-state lifetimes typical for complexes of ruthenium and other precious metals are often essential to ensure high performance. There is much interest in replacing these scarce elements with Earth-abundant metals, with iron and copper being particularly attractive owing to their low cost and non-toxicity. But despite the exploration of innovative molecular designs, it remains a formidable scientific challenge to access Earth-abundant transition-metal complexes with long-lived charge-transfer excited states. No known iron complexes are considered photoluminescent at room temperature, and their rapid excited-state deactivation precludes their use as photosensitizers. Here we present the iron complex [Fe(btz)3]3+ (where btz is 3,3′-dimethyl-1,1′-bis(p-tolyl)-4,4′-bis(1,2,3-triazol-5-ylidene)), and show that the superior σ-donor and π-acceptor electron properties of the ligand stabilize the excited state sufficiently to realize a long charge-transfer lifetime of 100 picoseconds (ps) and room-temperature photoluminescence. This species is a low-spin Fe(iii) d5 complex, and emission occurs from a long-lived doublet ligand-to-metal charge-transfer (2LMCT) state that is rarely seen for transition-metal complexes. The absence of intersystem crossing, which often gives rise to large excited-state energy losses in transition-metal complexes, enables the observation of spin-allowed emission directly to the ground state and could be exploited as an increased driving force in photochemical reactions on surfaces. These findings suggest that appropriate design strategies can deliver new iron-based materials for use as light emitters and photosensitizers.

doi: 10.1038/nature21430