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Túneles cuánticos de magnetización en un nuevo imán [Mn18]2+ de una sola molécula con s = 13
Euan K Brechin1, Colette Boskovic, Wolfgang Wernsdorfer
1Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, USA.
Journal of the American Chemical Society
|August 15, 2002
Resumen
Este estudio informa de un nuevo grupo de manganeso, [Mn18O14(O2CMe) 18 ((hep) 4 ((hepH) 2 ((H2O) 2 ((ClO4) 2 (1), un imán de una sola molécula (SMM) con el mayor espín y la mayor nuclealidad hasta la fecha. Muestra túnel cuántico de magnetización (QTM) a bajas temperaturas.
Área de la Ciencia:
- Química Inorgánica La Química Inorgánica es la química inorgánica.
- Ciencia de los materiales Ciencia de los materiales.
- Magnetoquímica es la Magnetoquímica.
Sus antecedentes:
- Los imanes de una sola molécula (SMM) son compuestos moleculares que exhiben una lenta relajación magnética.
- El desarrollo de SMM de alta nucleariedad con grandes valores de espín es crucial para el avance del magnetismo molecular.
- Comprender la relación entre la estructura y las propiedades magnéticas es clave para diseñar nuevos SMM.
Objetivo del estudio:
- Para sintetizar y caracterizar un nuevo cúmulo de manganeso de alta nucleariedad.
- Para investigar las propiedades magnéticas del racimo sintetizado, centrándose en su potencial como un imán de una sola molécula.
- Para explorar el fenómeno del túnel cuántico de magnetización (QTM) en este complejo.
Principales métodos:
- Reacción de 2-(hidroxietil) piridina (hepH) con precursores específicos de manganeso en el acetonitrilo.
- Cristalografía de rayos X para la determinación estructural del complejo [Mn18O14(O2CMe) 18 ((hep) 4 ((hepH) 2 ((H2O) 2) ((ClO4) 2 (1).
- Mediciones de susceptibilidad magnética de corriente continua (DC) y corriente alterna (AC) de temperatura variable, estudios de magnetización y análisis de desintegración de magnetización DC.
Principales resultados:
- Aislamiento del complejo 2MnII,16MnIII (1) con una unidad central Mn4O6 y dos unidades Mn7O9, exhibiendo un espín total S = 13.
- Confirmación del comportamiento del imán de una sola molécula a través de estudios de susceptibilidad a la CA y observación de histeresis por debajo de 1,0 K.
- Determinación de una barrera efectiva a la relajación (Ueff) de 14,8 cm-1 y observación de la relajación independiente de la temperatura por debajo de 0,25 K, indicativo del túnel cuántico de la magnetización (QTM).
Conclusiones:
- El Complejo 1 representa el mayor espín y la mayor nuclealidad del imán de molécula única (SMM) para exhibir el túnel cuántico de la magnetización (QTM).
- El estudio demuestra la viabilidad de construir complejos grupos de manganeso polinuclear con propiedades magnéticas significativas.
- Este trabajo contribuye a la comprensión fundamental de los fenómenos magnéticos en materiales moleculares y el diseño de sistemas magnéticos avanzados.
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