TTF and derivatives

There has again been a large amount of work on tetrathiafulvalenes (TTFs) and derivatives and a short review of such compounds has appeared <99M1617>. New simple TTF derivatives prepared include the terakis-bromomethyl compound <99TL2927> and doubly C-labelled... 

Compound I may be prepared by the reduction of carbon disulfide either electrochemically6 or by use of an alkali metal.7 In this report we present the synthesis of BEDT-TTF, and derivatives, via the procedure just described beginning with the alkali metal reduction of carbon disulfide. In our hands we find this procedure easier to set up and use than that involving the electrolytic reduction of carbon disulfide. 

Studies of new materials based on substituted TTF and derivations of TTN will be presented. 

Inagi S, Naka K, Chujo Y (2007) Functional polymers based on electron-donating TTF and derivatives. J Mater Chem 17 4122-4135... 

Tetrathiafulvalene and its derivatives are electroactive and can be easily and reversibly oxidized to TTF + and TTF2 +. The TTF skeleton now occupies a critical position as far as switchable properties are concerned, and behaves as a key unit for a number of supramolecular concepts. For instance, the recent years have seen an increasing contribution of TTF to the preparation of interlocked compounds such as rotaxanes and catenanes. These systems are of particular importance as candidates for molecular machines. 

Oxidation of TTF and its derivatives induces the transformation from neutral species into cationic ones, namely, cation radicals (TTF +) and dications (TTF2+). Moreover, TTF, TTF +, and TTF2+ exhibit different absorption spectra. Taking these advantages of TTF new TTF-based redox fluorescence switches and chiral switches have been recently reported. 

Fig-1 TTF and some of the chiral donor molecules derived from it... 

Tetracyanoquinodimethane (TCNQ) and many of its derivatives are easily reduced to anions of the type TCNQ-, which form salts with various cations. With many cations, e.g., tetrathiafulvalene cations (TTF+), and N-methyl phenazinium cations (NMP+), the TCNQ- anions form electronically conducting salts (- molecular metals, -> charge-transfer complexes) that can be used as electrodes, especially because of their electrocatalytic properties (- biosensors, -> electrocatalysis, -> molecular metals) [i,ii]. TCNQ undergoes insertion electrochemical reactions (-> insertion electrochemistry) leading to TCNQ salts [iii, iv]. Polymers... 

Tetrathiafulvalene electrodes — Tetrathiafulvalene (TTF) and many of its derivatives are easily oxidized to form cations of the type TTF+. With various anions, most prominent is the tetracyanoquinodimethane anion (TCNQ-), these cations form - charge-transfer complexes, i.e., salts with metal-like conductivities (- molecular metals). These salts are used in electrochemistry as electrodes or to modify the surface of electrodes, for the purpose of achieving desirable electrocatalytic properties (- electrocatalysis). Tetrathiafulvalene-substituted polystyrenes have also been synthesized and used as modified electrodes [ii]. 

Some homoleptic unsymmetrical (dmit/mnt, dmit/tdas) dithiolene nickel complex-based D-A compounds with D = TTF and EDT-TTF also exhibit metal-like conductivity (see Table I) (101). Their molecular structure is shown in Scheme 3. The unsymmetrical tetraalkylammonium salts [MLjLJ- (M = Ni, Pd, Pt) have been prepared by ligand exchange reaction between tetraalkylammonium salts of MLj and ML21 (128, 129) and the D-A compounds have been synthesized by electrooxidation. Among these complexes, only the Ni derivatives exhibit metallic-like properties, namely, TTF[Ni(dmit)(mnt)] (metallic down to --30 K), a-EDT-TTF[Ni(dmit)(mnt)] (metallic down to 30 K), TTF[Ni(dmit)(tdas)] (metallic down to 4.2 K), and EDT-TTF[Ni(dmit)(tdas)] (metallic down to --50 K) (see Table I). The complex ot-EDT-TTF-[Ni(dmit)(mnt)J is isostructural (130) to a-EDT-TTF[Ni(dmit)2)] [ambient pressure superconductor, Section II.B.2 (124)]. Under pressure, conductivity measurements up to 18 kbar show a monotonous decrease of the resistivity but do not reveal any superconducting transition (101). 

---