Substituted BEDT‐TTF Derivatives: Synthesis, Chirality, Properties and Potential Applications

Abstract

Abstract.The increasing availability of functionalized BEDT-TTF derivatives in both racemic and enantiopure forms opens up great opportunities for preparing multifunctional materials and chiral conducting systems in the form of crystals, thin films and polymers. Functionalities such as amino and carboxyl will allow attachment to other molecular systems, while intermolecular interactions between substituents, e.g. hydrogen bonding and halegon---halegon interactions, provides additional tools for designing solid state radical cation structures. In this review the syntheses of substituted derivatives of BEDT-TTF and closely related donors are surveyed, along with the structures and properties of the radical cation salts so far prepared, as a stimulus for future application of these versatile and attractive molecules. Particular attention is paid to the preparation of single enantiomers, and to the stereochemical consequences of the synthetic procedures. IntroductionOrganosulfur donor molecules have been a major focus for research in the preparation of molecular conducting systems, with tetrathiafulvalene 1 and its derivatives playing a leading role initially.1 However, breakthroughs in the last decade for preparing superconducting and hybrid materials have featured bis(ethylenedithio)tetrathiafulvalene 2, also known as BEDT-TTF or ET.2 This molecule shows two reversible oxidations at 0.50 and 0.91 V relative to the Ag/AgCl electrode, ca. 0.15 V more positive than those for TTF, and has been converted into a very large number of radical cation salts. These have been studied by a wide range of techniques stimulated in part by formation of superconducting radical cation salts with anions Cu(NCS) 2

Selective monosulfoxidation of tetrathiafulvalenes into chiral TTF‐sulfoxides

“…17 The possible influence of the structural disorder in the conducting properties of chiral TTF-based conductors has been initially addressed by Dunitz and Wallis through the synthesis of the first chiral TTF derivative, namely S,S,S,S-tetramethyl-BEDT-TTF (BEDT 5 bis(ethylenedithio). 18 Subsequently, many other chiral BEDT-TTF derivatives, with the chiral information provided by asymmetric carbon atoms in the backbone of the TTF-tetrathio unit, have been reported, especially by Wallis et al 19,20 Interestingly, amphiphilic TTF derivatives containing chiral long alkyl chains have also been described. 21 Polymerization of such a compound, bearing an isocyanide group, afforded a polymer in which chiral teleinduction was evidenced.…”

Tetramethyl‐Bis(ethylenedithio)‐Tetrathiafulvalene (TM‐BEDT‐TTF) Revisited: Crystal Structures, Chiroptical Properties, Theoretical Calculations, and a Complete Series of Conducting Radical Cation Salts

“…4 The access to a large library of chiral precursors is thus of paramount importance, and, accordingly, several families of TTFs, in which the chiral information has been addressed in different ways, have been described. 1 For example, derivatives with stereogenic carbon atoms such as bis(ethylenedithio)-tetrathiafulvalenes (BEDT-TTF), 5,6 TTF-oxazolines [7][8][9][10][11][12] and bis(oxazolines), 13,14 bis(pyrrolo)-TTFs, 15 C 3 symmetric tris(TTF) affording supramolecular helical aggregates, 16,17 or with stereogenic sulfur atoms in TTF-sulfoxides 18,19 have been reported. Complete series of conducting salts, comprising both enantiomeric and racemic forms, have been prepared by electrocrystallization of EDT-TTF-oxazolines (EDT = ethylenedithio).…”

Ab initio investigation of nonlinear optical, electronic, and thermodynamic properties of BEDT-TTF molecule: doping with boron

“…Moreover, the works of Flakina et al [ 8 ], revealed new molecules from the monosubstituted anion of isocyanuric acid on BEDT-TTF and their crystal structures were determined. The chirality of substituted BEDT-TTF derivatives was in the heart of work of Wallis et al [ 9 ]. In addition, gives opportunities for preparing multifunctional materials.…”