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Inducir el cruce de espín en los polielectrolitos metalo-supramoleculares a través de una transición de fase

Yves Bodenthin¹, Ullrich Pietsch, Helmuth Möhwald

¹Department of Physics, University of Potsdam, D-14424 Potsdam, Germany, Max Planck Institute of Colloids and Interfaces, D-14424 Potsdam, Germany. kurth@mpikig-golm.mpg.de

Journal of the American Chemical Society

|March 3, 2005

Resumen

Una transición de espín reversible de estados de espín bajo a estados de espín alto en complejos de hierro se logra mediante la inducción de tensión mecánica a través de una transición de fase en mesofasas anfifílicas. Este método permite propiedades magnéticas sintonizables en materiales moleculares.

Área de la Ciencia:

Ciencia de los materiales Ciencia de los materiales.
Química supramolecular de las moléculas.
El magnetismo es el magnetismo.

Sus antecedentes:

Las mesofasas anfifílicas exhiben transiciones de fase que pueden influir en los arreglos moleculares.
Los centros de coordinación de iones metálicos son sensibles a su geometría circundante, lo que afecta las propiedades electrónicas.
Las transiciones de espín en complejos de metales de transición ofrecen comportamientos magnéticos sintonizables.

Objetivo del estudio:

Explorar las transiciones de fase en las mesofasas anfifílicas para inducir la tensión mecánica.
Para controlar deliberadamente las transiciones de espín en los centros de coordinación de iones metálicos.
Desarrollar nuevas arquitecturas magnéticas moleculares con propiedades sintonizables.

Principales métodos:

Utilizando un complejo de coordinación metalo-supramolecular polielectrolito-anfifil.
Empleando el Fe (II) como el metal de transición central y los fosfatos dialquilo como anfifiles.
Investigando las propiedades magnéticas en una multicapa de Langmuir-Blodgett.

Principales resultados:

La fusión de las cadenas de alquilo indujo la distorsión de la geometría de coordinación.
La disminución de la división del campo cristalino condujo a una transición reversible de estado de espín bajo a alto.
Demostró una transición diamagnético-paramagnético impulsado por la tensión mecánica.

Conclusiones:

Las transiciones de fase en las mesofasas anfifílicas pueden inducir de forma controlada la tensión mecánica.
Esta tensión modula de manera reversible los estados de espín en los complejos metálicos.
El concepto permite el diseño de diversas arquitecturas magnéticas moleculares.

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