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Spin-glass behavior of a hierarchically-organized, hybrid microporous material, based on an extended framework of octanuclear iron-oxo units.
Cao, Xin-Yi; Hubbard, Jeremiah W; Guerrero-Medina, Jennifer; Hernández-Maldonado, Arturo J; Mathivathanan, Logesh; Rinaldi, Carlos; Sanakis, Yiannis; Raptis, Raphael G.
Afiliación
  • Cao XY; Department of Chemistry and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00936-8377, USA.
Dalton Trans ; 44(7): 3399-409, 2015 Feb 21.
Article en En | MEDLINE | ID: mdl-25601767
Inspired by the stepwise addition of octanuclear iron units into mammalian ferritin, a "stop-and-go" synthesis strategy was used to prepare two microporous (Langmuir surface area, 490 m(2) g(-1); effective pore size, 4-5 Å) hierarchical materials {[Fe8(µ4-O)4(µ-pz)12Cl0.3(µ-O)1.85}n () and {[Fe8(µ4-O)4(µ-4-Me-pz)12Cl0.4(µ-O)1.8}n (), which are new members of the EO2 family of polymeric materials (E = C, Si and Ge). The secondary building units (SBUs) E = [Fe8(µ4-O)4(µ-4-R-pz)12] (Fe8) are nanoscale pseudo-spherical clusters, rather than single atoms, forming µ-oxo Fe-O-Fe linkages between Fe8-SBUs. The characteristic Fe-O-Fe asymmetric stretching mode in the infrared (IR) spectra of these compounds appearing at around 800 cm(-1) suggest the formation of approximately linear µ-oxo Fe-O-Fe linkages between Fe8-SBUs in and . We employ the concept of continuous random network (CRN) to describe for the first time the framework features of a Fe8-based amorphous materials, in which the average connecting numbers of each Fe8-cluster are ∼3.7 and ∼3.6 for and , respectively. (57)Fe-Mössbauer spectroscopic analysis provides insights to the intercluster connectivity of and on one hand and to their magnetic properties on the other, evident by a magnetic split sextet below 30 K. The combination of Mössbauer spectroscopy and magnetism measurements reveals a spin-glass behavior with Tg of ∼30 K. The hierarchical porous materials and straddle the gap between metal oxides and metal-organic frameworks (MOFs). This study may open an alternative way for the development of multifunctional materials based on high nuclearity metal clusters.

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Dalton Trans Asunto de la revista: QUIMICA Año: 2015 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Idioma: En Revista: Dalton Trans Asunto de la revista: QUIMICA Año: 2015 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido