Jump to main content
Jump to site search
PLANNED MAINTENANCE Close the message box

Scheduled maintenance upgrade on Thursday 4th of May 2017 from 8.00am to 9.00am (BST).

During this time our websites will be offline temporarily. If you have any questions please use the feedback button on this page. We apologise for any inconvenience this might cause and thank you for your patience.


Issue 42, 2016
Previous Article Next Article

A giant negative magnetoresistance effect in an iron tetrabenzoporphyrin complex

Author affiliations

Abstract

By measuring the electrical resistivity in TPP[FeIII(tbp)(CN)2]2 (TPP = tetraphenylphosphonium and tbp = tetrabenzoporphyrin) under the application of a static magnetic field, a giant negative magnetoresistance (MR) effect with high anisotropy is observed. More specifically, the MR ratio at 13 K under a field of 9 T perpendicular to the c axis is −70%, whereas the MR ratio under a field parallel to the c axis is −40%. Furthermore, electron spin resonance (ESR) measurements indicate large anisotropy in the principal g-values of d spin (S = 1/2) in the [FeIII(tbp)(CN)2] unit; the g1 value almost perpendicular to the tbp plane and the g2 and g3 values almost parallel to the tbp plane are 3.60, 1.24, and 0.39, respectively. It is revealed that the anisotropy in the MR effect arises from the anisotropy in the d spin, suggesting that the d spins in TPP[FeIII(tbp)(CN)2]2 affect the π-conduction electron via the intramolecular π–d interaction. The anisotropy and magnitude in the giant negative MR effect for TPP[FeIII(tbp)(CN)2]2 are smaller than the corresponding values for the isostructural phthalocyanine (Pc) analogue TPP[FeIII(Pc)(CN)2]2. This is consistent with the fact that the intermolecular antiferromagnetic d–d interaction in TPP[FeIII(tbp)(CN)2]2 (suggested by the Weiss temperature: Θ = −8.0 K) is weaker than that in TPP[FeIII(Pc)(CN)2]2 (Θ = −12.3 K). This indicates that the minor modification in coordination complexes can significantly affect the MR effect via tuning the intermolecular d–d interaction as well as the intermolecular π–π overlap.

Graphical abstract: A giant negative magnetoresistance effect in an iron tetrabenzoporphyrin complex

Back to tab navigation
Please wait while Download options loads

Supplementary files

Publication details

The article was received on 14 May 2016, accepted on 20 Jul 2016 and first published on 21 Jul 2016


Article type: Paper
DOI: 10.1039/C6DT01911K
Citation: Dalton Trans., 2016,45, 16604-16609
  •   Request permissions

    A giant negative magnetoresistance effect in an iron tetrabenzoporphyrin complex

    M. Nishi, M. Ikeda, A. Kanda, N. Hanasaki, N. Hoshino, T. Akutagawa and M. Matsuda, Dalton Trans., 2016, 45, 16604
    DOI: 10.1039/C6DT01911K

Search articles by author