Organic metals and superconductors

The synthesis of the first organic metal TTF-TCNQ was reported in 1973 by Coleman etal. and Ferraris et alP In this compound, TTF and TCNQ molecules are in 1 1 ratio and form separate stacked donor (TTF) columns and stacked acceptor (TCNQ) columns. A partial charge transfer between TTF and TCNQ transforms the molecular stacks into one-dimensional conductive paths via the formation of partially filled bands. Although TTF-TCNQ shows metallic conductivity down to around 60 K, it abruptly transfers to an insulator below 54 K, which was explained by a charge-density wave (CDW) phase-locking (Peierls transition ) due to its one dimensionality. 

In the process towards stable organic metals and superconductors, increasing the dimensionality could be a way to avoid the ubiquitous metal-insulator transition, which inevitably occurs in one-dimensional electronic systems. Compared with TTE and TMTSF, BEDT-TTF 

Based on the guideline that compounds exhibiting larger cell volume per BEDT-TTF molecule have a tendency to higher values of T various kinds of BEDT-TTF salts with polymeric anions have been synthesised. 

The K-type BETS salts with [MX4] anions show interesting phenomena at low temperatures. For example, K-[BETS]2[FeBr4] remains metallic down to 1.1 K. Although it shows an antiferromagnetic transition at 

it retains metallic conductivity. Upon decreasing the temperature, it finally turns to a superconductor below 1.1 K, where antiferromagnetic ordering still coexists. Furthermore, the K-[BETS]2[FeBr4] salts also show FISC state under 12.5 The detailed Se NMR studies on the 

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Cowan DO, Fortkort JA, Metzger RM (1991) Design constraints for organic metals and superconductors. In Metzger RM, Day P, Papavassiliou GC (eds) Lower-dimensional systems and molecular electronics. NATO ASI Ser, vol B248. Plenum Press, New York,... 

The results were promising, but did not last long because of the discovery of inorganic ceramics. The ceramics displayed superconductivity without any cooling (Vanderah 1992). Nevertheless, organic metal and superconductors have their advantages, and investigation is carried out in this direction. 

Wosnitza J (1996) Fermi surfaces of low-dimensional organic metals and superconductors. Springer, Berlin... 

Shibaeva RP, Kaminskii VF, Yagubskii EB (1985) Crystal structures of organic metals and superconductors of (BEDT-TTF)-l system. Mol Cryst Liq Cryst 119 361-373... 

All these successes were important, but their significance was lessened because inorganic ceramics had been discovered. The ceramics displayed superconductivity with no cooling at all (Vanderah, 1992). Nevertheless, organic metals and superconductors have their advantages, and investigations in this direction continue. 

The search for new organic metals and superconductors has attracted a great deal of attention in synthetic chemistry and material science since the discovery of high electrical conductivity in conjugated polymers such as polyacetylene [1], Lots of theoretical studies have been carried out in order to understand the mechanism of conductivity and superconductivity in the conjugated polymers and related... 

Pron A Rannou P, Processible conjugated polymers From organic semiconductors to organic metals and superconductors, Prog. Polym. Sci, 2002, 27, 135-190. 

Design Rules for Crystalline Organic Metals and Superconductors. Several semiempirical rules [23-26], summarized in five requirements, may help to find new high-conductivity compounds and superconductors ... 

Besides the organic metals and superconductors based on the donor molecule ET numerous metallic organic charge transfer salts composed of different donors and acceptors have been synthesized. However, only a small number of these salts become superconducting, usually at rather low temperatures, and even less have been investigated in the same detail as the ET compounds. Apparently, the generally low crystal quality of the non-ET materials permitted only a few Fermi surface studies by SdH or dHvA experiments. 

Fermi Surfaces of Low-Dimensional Organic Metals and Superconductors... 

Asa review see for example, J. Wosnitza, Fermi Surfaces of Low-Dimensional Organic Metals and Superconductors, Springer Tracts in Modem Physics Vol. 134 Springer, Berlin, 1996. 

Organic metals and superconductors based on fe(ethylenedithio)tetraselena-fulvalene (BETS) 04CRV5265. 

A. Pron, P. Rannou, Processible Conjugated Polymers From Organic Semiconductors to Organic Metals and Superconductors, Prog. Polym. Sci. 27 (2002) 135. 

Pron, A. and Rannou, P. (2002) Processable conjugated polymers from organic semiconductors to organic metals and superconductors. Pr<. ... 

Jensen was an efficient transmitter of the tradition of sulfur chemistry in Denmark, and several young scientists were inspired by him. For example, Bechgaard became a leading figure in the successful search for organic metals and superconductors ("Bechgaa salts") via his deep insight into sulto and selenium chemistry. 

Prasad GK, Radhakrishntm TP, Kumar DS, Krishna MG (2(X)5) Ammonia sensing characteristics of thin film based on polyelectrolyte templated polyaniline. Sens Actuators B 106 626-631 Pron A, Rannou P (2002) Processible conjugated polymers from organic semiconductors to organic metals and superconductors. Prog Polym Sd 27 135-190... 

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