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Intramolecular spin alignment in photomagnetic molecular devices: a theoretical study

  • Ciofini, Ilaria Laboratoire d'Électrochimie et Chimie Analytique, École Nationale Supérieure de Chimie de Paris, France
  • Lainé, Philippe P. Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université René Descartes, Paris, France
  • Zamboni, Marta Laboratoire d'Électrochimie et Chimie Analytique, École Nationale Supérieure de Chimie de Paris, France
  • Daul, Claude Département de Chimie, Université de Fribourg, Switzerland
  • Marvaud, Valérie Laboratoire de Chimie Inorganique et Matériaux Moléculaires, Université Pierre et Marie Curie, Paris
  • Adamo, Carlo Laboratoire d'Électrochimie et Chimie Analytique, École Nationale Supérieure de Chimie de Paris, France
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    27.03.2007
Published in:
  • Chemistry - A European Journal. - 2007, vol. 13, no. 19, p. 5360 - 5377
density functional calculation
magnetic properties
molecular spintronics
photomagnetic molecular devices
radicals
English Ground- and excited-state magnetic properties of recently characterized π-conjugated photomagnetic organic molecules are analyzed by the means of density functional theory (DFT). The systems under investigation are made up of an anthracene (An) unit primarily acting as a photosensitizer (P), one or two iminonitroxyl (IN) or oxoverdazyl (OV) stable organic radical(s) as the dangling spin carrier(s) (SC), and intervening phenylene connector(s) (B). The magnetic behavior of these multicomponent systems, represented here by the Heisenberg-Dirac magnetic exchange coupling (J), as well as the EPR observables (g tensors and isotropic A values), are accurately modeled and rationalized by using our DFT approach. As the capability to quantitatively assess intramolecular exchange coupling J in the excited state makes it possible to undertake rational optimization of photomagnetic systems, DFT was subsequently used to model new compounds exhibiting different connection schemes for their functional components (P, B, SC). We show in the present work that it is worthwhile considering the triplet state of anthracene, that is, P when promoted in its lowest photoexcited state, as a full magnetic site in the same capacity as the remote SCs. This framework allows us to accurately account for the interplay between transient (³An) and persistent (IN, OV) spin carriers, which magnetically couple according to a sole polarization mechanism essentially supported by phenyl connector(s). From our theoretical investigations of photoinduced spin alignment, some general rules are proposed and validated. Relying on the analysis of spin-density maps, they allow us to predict the magnetic behavior of purely organic magnets in both the ground and the excited states. Finally, the notion of photomagnetic molecular devices (PMMDs) is derived and potential application towards molecular spintronics disclosed.
Faculty
Faculté des sciences et de médecine
Department
Département de Chimie
Language
  • English
Classification
Chemistry
License
License undefined
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/300428
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