Tetracyano--quinodimethane TCNQ derivatives

As is well known in the literature, the TCNQ molecule was first reported to form semiconducting salts in 1962 

Although this method has been said to be capricious [23], the reaction seems to be of general applicability at least for the preparation of tri- or tetrasubstituted TCNQ derivatives (7) [24]. 

A twin-TCNQ-type acceptor (11,11,12,12,13,13, 14,14, - octacyano -1,4,5,8 - anthradiquinotetramethane, OCNAQ) (12) has been reported by Mitsuhashi et al. [25] as the first molecule containing two TCNQ nuclei linked together through two methylidyne (-CH=) groups. The synthesis takes place by bromination of 

The Hiickel molecular orbital theory shows that the lowest unoccupied molecular orbitals (LUMO) of the novel acceptor (OCNAQ) and TCNQ have equal energy and the charge density resulting from the introduction 

Theoretical calculations have been carried out in order to understand the reduction process of the parent TCNQ [26]. The evolution of the geometry and electronic structure of the molecule upon reduction have been calculated for the TCNQ and also for its anion and dianion. 

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Interesting photoinduced electron-transfer reactions in mixed films of r-conjugated polymers and a homologous series of tetracyano-p-quinodimethane (TCNQ) derivatives have been recently reported [135]. Photoinduced absorption (PIA) and photoluminescence experiments have been carried out to study the photoexcitation of poly[2-methoxy-5-(2 -ethylhexy-loxy)-l,4-phenylenevinylene] (MEH-PPV) [136] and poly[3-(2-(3-methylbutoxy)ethyl)thiophene]... 

Salts Derived from 7,7,8,8-Tetracyano-p-quinodimethane (TCNQ, 41)... 

In this context, it is interesting that the first examples of mesomorphic CT complexes of discoid or sheet-like donor compounds and a strong electron acceptor [7,7,8,8-tetracyano-1,4-quinodimethane (TCNQ)] constitute an exception from the usually observed behavior. These complexes of bi-4-H pyran or bi-4-H thiopyran derivatives carrying four alkyl- or alkyloxy-phenyl substituents with TCNQ (see Fig. 2), have been prepared as organic conductors [40]. The neat alkylphenyl derivatives in the bi-4-H pyran series and alkyl- or alkyloxy-phenyl-substituted bi-4-H thiopyran donors are mesomorphic [40], but the structures of their mesophases are still not clear. 

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