Room-temperature molecule-based magnets

Room-temperature magnets belonging to the Prussian blue family were obtaine d recently through mild chemistry methods, i.e. molecular solution chemistr y at room temperature and pressure. The paper describes the rational way fo llowed to reach this goal and the prospects opened. First, the structure of Prussian blues and how it allows variation of the electronic structure and exchange interaction through the cyanide bridge is recalled. Then it is sh own how the systematic use of orbital models and simple semiempirical calcu lations, combined with the Neel molecular field approach, helps in increasi ng the Curie temperature up to room temperature in vanadium-chromium deriva tives. Some methods are then proposed to improve the magnetic properties an d some examples of applications in demonstrators, devices, photomagnetism, etc, are given. Finally, we mention some exciting challenges in molecular m agnetism, including the preparation of single molecule magnets at room temp erature.