A Cobalt Pyrenylnitronylnitroxide Single‐Chain Magnet with High Coercivity and Record Blocking Temperature. Issue 18 (18th March 2014)

• Record Type: Journal Article
• Authors: Vaz, Maria G. F.; Cassaro, Rafael A. Allão; Akpinar, Handan; Schlueter, John A.; Lahti, Paul M.; Novak, Miguel A.
• Is Part Of: Chemistry. Volume 20:Issue 18(2014)
• Page Start: 5460
• Page End: 5467
• Publication Date: 2014-03-18
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201304852
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Coordination of a [Co(hfac)₂] moiety (hfac=hexafluoroacetylacetonate) with a nitronylnitroxide radical linked to bulky, rigid pyrene (PyrNN) gives a helical 1:1 chain complex, in which both oxygen atoms of the radical NO^. groups are bonded to Co^II ions with strong antiferromagnetic exchange. The complex shows single‐chain magnet (SCM) behavior with frequency‐dependent magnetic susceptibility, field‐cooled and zero‐field‐cooled susceptibility divergence with a high blocking temperature of around 14 K (a record among SCMs), and hysteresis with a very large coercivity of 32 kOe at 8 K. The magnetic behavior is partly related to good chain isolation induced by the large pyrene units. Two magnetic relaxation processes have been observed, a slower one attributable to longer, and a faster one attributable to short chains. No evidence of magnetic ordering has been found.</p> </abstract>