The discovery of Single Molecule Magnets (SMMs) has represented a revolution in the field of molecular magnetism. Many research groups have focused their efforts on the development of new SMMs. For applications, including putative technological applications, however, the further step of arranging those compounds into well-ordered structures still is a pending issue. Coordination chemistry is proving to be a powerful tool for the preparation of polymeric nets of SMMs. As described in a recent review by Clerac, there are very few examples of SMMs arranged in networks. As we propose in this presentation, the number and functional possibilities of SMM networks can readily be increased in the case of citrate cubanes. The transition-metal citrate cubane [M4citrate4]8- is a symmetrical, anionic molecular fragment that possesses twelve partially negatively charged oxygen atoms (and twelve coordinated but reactive oxygen centers) around its periphery. The cobalt variants have proved to be SMMs, as demonstrated by Murrie et al. and by others. Interestingly, all of the negatively charged points on the fragment surface are potential linkage positions for metal atoms whose adhesion can give extended networks with dimensionalities ranging from zero- to three. In this presentation we apply this viewpoint to the previously reported [M4citrate4]8- cubanes with transition metal centres and to new ones, giving compounds with more than 10 different combinations of linkage points. Some of these products present an unexpected variety of magnetic and dynamic phase behaviour, including chemical reactions, phase transitions and proton transport. All of these products have different patterns of peripheral metal-atom linkage to the 12 surface-resident and 12 encrusted oxygen atoms of the cubane fragment. These results show that transition metal citrate cubanes are excellent synthons for the preparation of a potentially boundless family of networks of ordered SMMs with a high probability of finding new magnetic and dynamic properties. A systematic naming scheme for the citrate cubane topology is used to provide simple descriptions of the diverse linkage geometries found to date.

Funding was provided by the Ministerio de Ciencia e Innovación (Spain) (Grants MAT2007- 61621, MAT2008-04350, MAT2009-13977-C03, MAT2011-27233-C02-01 and MAT2011-27233-C02-02). European Union Regional Development Fund (FEDER) (program CONSOLIDER-INGENIO in Molecular Nanoscience (reference CSD 2007-00010)). EFV thanks the Ministry of Education (Spain) for a pre-doctoral scholarship under the program ‘Becas y Contratos FPU’ (reference AP2009-4211). Funding was also provided by the Diputación General de Aragón (Spain).

Resumen del trabajo presentado a la: "14th International Conference on Molecule-Based Magnets" celebrada en San Petersburgo (Rusia) del 5 al 9 de julio de 2014.

Peer reviewed