If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.



A cozy carbon wrap for osmium

Ligand features an unprecedented five carbons bound to a metal, with the complexes showing promise as photothermal cancer therapy agents

by Stephen K. Ritter
September 19, 2016 | A version of this story appeared in Volume 94, Issue 37

In high-coordination-number metal complexes, the coordinating atoms on the ligand are most often heteroatoms, such as nitrogen, oxygen, or phosphorus. Carbon is typically not involved. A team including Congqing Zhu, Caixia Yang, Xin Lu, Gang Liu, and Haiping Xia of Xiamen University has turned that situation completely around by preparing an unprecedented pentadentate chelating ligand in which all five metal-binding atoms are carbons—a new record for planar carbon coordination (Sci. Adv. 2016, DOI: 10.1126/sciadv.1601031). The metallacycles that are formed feature osmium encircled by a 12-carbon loop. The researchers suggest this new ligand, which they have named carbolong, could become a standard building block in coordination chemistry. Computational analysis indicates that the conjugated ligand could be viewed as a polycyclic aromatic hydrocarbon, but one that is distinctive from any observed before. The team has further shown that the osmium carbolongs absorb UV to near-infrared light. That makes the complexes promising candidates for photothermal therapy, in which localized heating caused by absorption of laser light destroys cancer cells. In collaboration with the U.S. National Institutes of Health, the Xiamen researchers have observed tumor regression in mice treated with an osmium carbolong.


This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.