The literature has shown numerous contributions on the synthesis and physicochemical properties of persistent organic radicals but there are a lesser number of reports about their use as building blocks for obtaining molecular magnetic materials exhibiting an additional and useful physical property or function. These materials show promise for applications in spintronics as well as bistable memory devices and sensing materials. This critical review provides an up-to-date survey to this new generation of multifunctional magnetic materials. For this, a detailed revision of the most common families of persistent organic radicals—nitroxide, triphenylmethyl, verdazyl, phenalenyl, and dithiadiazolyl—so far reported will be presented, classified into three different sections: materials with magnetic, conducting and optical properties. An additional section reporting switchable materials based on these radicals is presented (257 references).

The novel and exciting field of molecular spintronics has recently attracted a great deal of interest and promising results have already been reported. The utilisation of organic radicals that could favour spin polarisation and conservation during transport offers new possibilities; however, first a fundamental investigation of these materials, especially those deposited on surfaces, is required. Here we highlight our recent results regarding the functionalisation of surfaces with polychlorotriphenylmethyl (PTM) radicals following five different strategies in which interactions of different nature are involved (i.e. van der Waals, electrostatic, coordination bond and covalent bond). In all cases, it was proved that the magnetic character of the molecule persists on the surface.