Molecular coolers get JACS cover story

The cover story of the September 22^nd issue of The Journal of the American Chemical Society will feature an article from members of our team in collaboration with colleagues at Edinburgh, Berkeley and Columbia. Our work targeted the synthesis of molecular nanomagnets for enhanced magnetic refrigeration and the experimental verification of the relevant role played by the anisotropy in setting the performance of these coolers.

The use of methylene-bridged calix[4]arenes in 3d/4f chemistry produces a family of clusters of formula [Mn^III₄Ln^III₄], where Mn^III is a manganese ion and Ln^III a lanthanide ion. The molecular structure describes a square of Ln^III ions housed within a square of Mn^III ions. The anisotropy induced by setting Ln^III to be terbium or dysprosium ions results in (i) superparamagnetic behaviour of [Mn^III₄Tb^III₄] or [Mn^III₄Dy^III₄], respectively, with blocking temperatures in the temperature region below 1 K and (ii) poor performance of these clusters in terms of magnetic refrigeration. However, the replacement of the anisotropic terbium or dysprosium ions with the isotropic gadolinium ions results in a large number of molecular spin states that are populated even at the lowest investigated temperatures, while the ferromagnetic limit S = 22 is being approached only at the highest applied fields. This, combined with the high magnetic isotropy, makes [Mn^III₄Gd^III₄] an excellent magnetic refrigerant for low-temperature applications, providing for example a valid alternative to the use of ³He which is becoming rare and expensive.

Link to https://dx.doi.org/10.1021/ja104848m.

Also highlighted by the European Institute of Molecular Magnetism, SINC, madri+d, La Catedral Innova, Plica Zaragózame, Ecoticias, CTNoticias, RDi Press, Technology for life, La Flecha, Keegy, Black Capital, EveryDay Science, Bitacoras, Energium, Notas de ciencia, Ruoleima, Aragón Investiga.