HYBRID MATERIALS BASED ON POLYOXOMETALATES WITH SOLID STATE PROPERTIES

摘要

Molecular materials with cooperative physical properties constitute one of the most active focus of interest in contemporary materials science. An attractive chemical feature of these materials derives from the possibility of building them from molecular bricks using the advantages provided by molecular chemistry and the knowledge achieved over the last 20 years in the so-called molecular engineering. From the point of view of the physical properties, it is well known that molecular materials can exhibit the properties typically associated with the inorganic network solids, as for example metallic conductivity and superconductivity, ferromagnetism and non-linear optics. The field of molecular materials with electrical properties started in 1965 with the discovery of the first molecular metal, the salt (N-methylphenazenium)(TCNQ) (TCNQ = tetracyano-p-quino-dimethane) followed by the discovery in 1973 of the salt (TTF)(TCNQ) (TTF = tetrathiaful-valene, Figure 1), which constitutes the first example of metallic charge transfer complex (CTC) containing the organic donor TTF. Since then, the synthesis of radical salts and CTC with TTF and its derivatives (Figure 1) has given rise to thousands of molecular semiconductors, hundreds of metals and almost a hundred superconductors. The first of these molecular superconductors, the salts [TMTSF]_2X (X = [PF_6]~-, [AsF)_6]~-; TMTSF = tetramethyl-tetraselenafulvalene), were reported in 1979.