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A nanoporous molecular magnet with reversible solvent-induced mechanical and magnetic properties


Interest in metal–organic open-framework structures has increased enormously in the past few years because of the potential benefits of using crystal engineering techniques to yield nanoporous materials with predictable structures and interesting properties. Here we report a new efficient methodology for the preparation of metal–organic open-framework magnetic structures based on the use of a persistent organic free radical (PTMTC), functionalized with three carboxylic groups. Using this approach, we create an open-framework structure Cu3(PTMTC)2(py)6(CH3CH2OH)2(H2O), which we call MOROF-1, combining very large pores (2.8–3.1 nm) with bulk magnetic ordering. MOROF-1 shows a reversible and highly selective solvent-induced 'shrinking–breathing' process involving large volume changes (25–35%) that strongly influence the magnetic properties of the material. This magnetic sponge-like behaviour could be the first stage of a new route towards magnetic solvent sensors.

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Figure 1: Crystal structure of MOROF-1.
Figure 2: Real images of crystals of MOROF-1 followed with an optical microscope.
Figure 3: Guest exchange studies followed by magnetic and XRPD measurements.
Figure 4: Magnetic properties.


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This work was supported by the Programa Nacional de Materiales of the Dirección General de Investigación (Spain), under project MAGMOL. D.M. is grateful to the Generalitat de Catalunya for a predoctoral grant. We thank P. Gerbier of the Université Montpellier for TG-MS experiments and X. Alcobé of the Universitat de Barcelona for X-ray powder diffraction measurements.

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Correspondence to Jaume Veciana.

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Supplementary information

Figure 1S Magnetization value as a function of the applied field at a temperature of 2.5 K for MOROF-1

Figure 2S Reversible magnetic behavior of the amorphous and evacuated phase in contact with ethanol liquid, plot of magnetization value as a function of the applied field at a temperature of 2.5 K (PDF 891 kb)

Figure 3S Plots of χ'MT (top) and χ"MT (bottom) as a function of the temperature for MOROF-1 at the indicated frequencies

Figure 4S χT value as a function of the temperature for MOROF-1

Figure 5S (Left) χT value as a function of the temperature for complex Cu(PTMMC)2(H2O)3.

Figure 6S  Powder X-ray diffractogram of MOROF-1 (red) and MOOF-1 (black).

Structure The crystal structure of MOROF-1.

Movie 1 This video shows the "shrinking-breathing" process. (AVI 745 kb)

Movie 2 This video shows the shrinking process of one crystal followed with polarized light. (AVI 2002 kb)

Movie 3 This video shows the breathing process of one crystal followed with polarized light. (GIF 2403 kb)

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Maspoch, D., Ruiz-Molina, D., Wurst, K. et al. A nanoporous molecular magnet with reversible solvent-induced mechanical and magnetic properties. Nature Mater 2, 190–195 (2003).

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