The SimplisticBeauty of a Free Radical

- Korean scientistsconduct experiments with highly reactive nitric oxide (NO) to formN-heterocyclic carbine nitric oxide radicals (NHCNOs)

June 18 , 2015

By Neil Mannix

The study was conducted at the Center for Self-Assembly and Complexitywithin the Institute for Basic Science (IBS) in South Korea. DirectorKimoonKim and his team experimented with nitric oxide, a highly stablemolecule of supreme importance in science. NO is highly reactive and a freeradical, meaning a single, unpaired electron is present in its molecule.

Put simply NO plays the role of a mediator between elements and helpsthem combine. Radicals are regularly generated in many metabolic pathways. Someof these radicals can exist in a free form and subsequently interact withvarious tissue components resulting in dysfunction. The potential role of freeradicals in the pathologyof several humandiseases has resulted in extensive research. However, because freeradical-mediated changes are pervasive and often poorly understood, thequestion of whether free radicals are a major cause of tissue injury and humandisease remains unanswered

Only a few organic compounds have been utilized to react with NO toform radical nitric oxide compounds and the development of such reactivity withNO using N-heterocyclic carbenes (NHCs) has not been reported to date. NHCs arenot well known to react with or stabilize main group radicals and radical ions.Main group radicals, along with nitrogen, include carbon and oxygen.

The Creation of NHCNOs

N-heterocyclic carbine nitric oxide radicals were prepared for thefirst time by direct addition of nitric oxide to two readily availableN-heterocyclic carbenes in solution phase. The compounds, stable in air and inwater, were fully characterized using X-ray crystallography and by a techniquecalled EPR which is used to studychemical species with unpaired electrons. A functioning group of molecules fromthe solid molecules obtained can be thermally transferred to another NHC,suggesting potential applications to NO delivery.  A light orange solid was the result of theexperiment.

Although nitrous oxide was dominantly formed during chemicaldecomposition of the experiment, nitric oxide was also found to be thermallytransferred to other N-heterocyclic carbenes. This suggests potentialbiological applications for NO delivery. Furthermore, this study adds anotherexample of stable singlet carbenes acting as mimics for transition metalcenters

Notes for editors

-        References

Junbeom Park, Hayoung Song,Youngsuk Kim,BitEun, Yonghwi Kim, Dae Young Bae, Sungho Park, Young Min Rhee, Won Jong Kim,Kimoon Kim, and Eunsung Lee, (2015), “N-Heterocyclic Carbene Nitric Oxide Radicals”, JACS, DOI:10.1021/jacs.5b01976

-        For further information or to requestmedia assistance, please contact: Mr. Shi Bo Shim, Head of Department ofCommunications, Institute for Basic Science (+82-42-878-8189; sibo@ibs.re.kr)or Ms. Sunny Kim, Department of Communications, Institute for Basic Science(+82-42-878-8135; Sunnykim@ibs.re.kr)

-        About the Institute for Basic Science(IBS)
IBS was founded in 2011 by the government of the Republic of Korea with thesole purpose of driving forward the development of basic science in Korea Itcomprises a total of 50 research centers in all fields of basic science,including mathematics, physics, chemistry, life science, earth science and interdisciplinaryscience. IBS haslaunched 24 research centers as of January 2015.There are eight physics, onemathematics, six chemistry, seven life science, and two interdisciplinaryresearch centers.