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International audience; Halogen bonding (XB) interactions are investigated in cation radical salts of bis(methylthio)-5,5'-diiodotetrathiafulvalene (1). Electrocrystallization of 1 in the presence of Bu NCl affords a 1 1 salt formulated as (E-1)Cl. Particularly strong I⋅⋅⋅Cl XB interactions are observed around the Cl anion with the distances at 78 % the sum of the van der Waals radii, a consequence of the XB charge activation in the cation radical. Moreover, the Cl environment is complemented by two extra S⋅⋅⋅Cl chalcogen bonding (ChB) interactions, an original feature among reported halide salts of TTF derivatives. Electrostatic potential calculations on the cation radical further demonstrate the efficient activation of the S atoms of the 1,3-dithiole rings (V =87.2 kcal/mol), as strong as with the iodine atoms (V =87.9 kcal/mol). The radical cations form weakly dimerized stacks, as confirmed by the variable-temperature magnetic susceptibility and the weak conductivity (4.8×10 S cm ).

International audience; Tetrathiafulvalene (TTF) derivatives are the most representative electroactive precursors for the preparation of crystalline conducting materials. The occurrence of mixed valence states, through electron delocalization, and strong intermolecular interactions are important prerequisite to account for high electronic conduction in the solid state and dimensionality of the material. In this respect the modulation of through space or through bond intramolecular electron communication can be efficiently achieved in heteroatom bridged bis(TTF) derivatives. Moreover, the bridging heteroatoms can engage, depending on their nature, in intermolecular interactions in the solid state. In this Review we focus on flexible and rigid bis(TTF) derivatives formulated as X(TTF)2 and X2(TTF)2 (X = Si, Ge, Sn, P, Sb, S, Se, Te) thus containing one or two bridges in ortho position. A special attention is given to the solid state structures of these precursors and their oxidized species, their electrochemical behavior, reactivity, role of the heteroatom in the establishment of intramolecular mixed valence and intermolecular interactions, and the conducting properties.

The synthesis of 2-N,N-dialkylamino-1,3-dithiolium salts is reviewed.

We investigate in this study, the quantum chemical computations of a series of tetrathiafulvalene derivatives linked to N-methylthiocarbamoyl group 1-4 using the DFT/B3LYP method with 6-31G (d,p) basis set. The optimized structures and geometrical parameters were determined by the same method cited above. In addition, a molecular electrostatic potential map (MEP) has been analyzed for predicting the reactive sites. The calculated HOMO and LUMO energies showed that charge transfer occurs within the molecule. The chemical reactivity parameters (chemical hardness and softness, electronegativity, chemical potential and electrophilicity index) were discussed clearly. To find out more reactive sites of the title molecules, condensed Fukui functions have been also calculated. Stability of the compounds arising from hyper-conjugative interaction and charge delocalization has been analyzed using Natural bond orbital (NBO) analysis. NLO properties related to polarizability and hyperpolarizability are also discussed to predict the applications of title compounds.

The synthesis of [2.2]paracyclophane derivatives containing tetrathiafulvalene units has been accomplished by the coupling reaction of 4-([2.2]paracyclophan-4-yl)-1,3-dithiol-2-thione in the presence of trimethylphosphite. The 1,3-dithiol-2-thione derivative was in turn synthesized by the regioselective bromination of 4-acetyl[2.2]paracyclophane, then through the corresponding dithiocarbamates and 1,3-dithiolium salts.

Enantiopure (R,R) and (S,S)-dimethyl-bis(ethylenedithio)tetrathiafulvalene monosulfones have been synthesized by the aerial oxidation of the chiral dithiolates generated from the propionitrile-protected precursors. Both enantiomers crystallize in the orthorhombic chiral space group P212121. They show a boat-type conformation of the TTF moiety, a rather rigid dithiin sulfone ring and the methyl groups in a bisequatorial conformation. Cyclic voltammetry measurements indicate fully reversible oxidation in radical cation and dication species.

International audience; The synthesis and properties of a series of bis-tetrathiafulvalenes (bis-TTFs) containing nitrophenyl, aminophenyl or dimethylaminophenyl is reported. The synthesis was carried out by using routes involving Wittig-type, cross-coupling, reduction and alkylation reactions. The electron donor ability of these new compounds has been measured by cyclic voltammetry (CV). Charge transfer complexes with tetracyanoquinodimethane (TCNQ) were prepared by chemical redox reactions. The complexes have been proven to give conducting materials.

Electrocrystallization of the (S,S,S,S) enantiomer of tetramethyl-bis(ethylenedithio)-tetrathiafulvalene donor 1 in the presence of the dianionic hexanuclear rhenium (III) cluster [Re6S6Cl8]2− affords a crystalline radical cation salt formulated as [(S)-1]2·Re6S6Cl8, in which the methyl substituents of the donors adopt an unprecedented all-axial conformation. A complex set of intermolecular TTF···TTF and cluster···TTF interactions sustain an original tridimensional architecture.

Tris-fused tetrathiafulvalene (TTF) derivatives, TTCn-TTPY, 2,2′-bis[4,5-alkylthio-(1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalenylidene] with four alkylthio chains [CnH2n+1S: n=3–5] are prepared and the structural and conducting properties are investigated. Crystals of the neutral molecules show very low electrical resistivity (400 Ω cm) as single-component pure organic materials. Irrespective of the alkylthio chain length, the crystal structures are so-called β″-type consisting of uniform stacks of the tris-fused TTF parts. Iodine-doped TTC3-TTPY exhibits metallic conductivity down to liquid helium temperature.

As the use of low-molecular-weight gelators (LMWGs) as components in single and multicomponent systems for optoelectronic and solar cell applications increases, so does the need for more functional gelators. There are relatively few examples of p-type gelators that can be used in such systems. Here, the synthesis and characterization of three amino-acid-functionalized p-type gelators based on terthiophene, tetrathiafulvalene, and oligo(phenylenevinylene) are described. The cores of these molecules are already used as electron donors in optoelectronic applications. These newly designed molecules can gel water to form highly organized structures, which can be dried into thin films that show p-type behavior.

While mechanical bonding stabilizes tetrathiafulvalene (TTF) radical dimers, the question arises: what role does topology play in catenanes containing TTF units? Here, we report how topology, together with mechanical bonding, in isomeric [3]- and doubly interlocked [2]catenanes controls the formation of TTF radical dimers within their structural frameworks, including a ring-in-ring complex (formed between an organoplatinum square and a {2+2} macrocyclic polyether containing two 1,5-dioxynaphthalene (DNP) and two TTF units) that is topologically isomeric with the doubly interlocked [2]catenane. The separate TTF units in the two {1+1} macrocycles (each containing also one DNP unit) of the isomeric [3]catenane exhibit slightly different redox properties compared with those in the {2+2} macrocycle present in the [2]catenane, while comparison with its topological isomer reveals substantially different redox behavior. Although the stabilities of the mixed-valence (TTF2)^(•+) dimers are similar in the two catenanes, the radical cationic (TTF^(•+))_2 dimer in the [2]catenane occurs only fleetingly compared with its prominent existence in the [3]catenane, while both dimers are absent altogether in the ring-in-ring complex. The electrochemical behavior of these three radically configurable isomers demonstrates that a fundamental relationship exists between topology and redox properties.

International audience; Organic pi-donors such as tetrathiafulvalenes (IT F) substituted by primary alkyl iodides (RI) may react in contact with polarized glassy carbon at potentials more negative than - 1 V vs. Ag/AgCl. Accordingly, useful heterogeneous layers are formed which are directly attached to a conducting surface. The present work focuses on the grafting of TTfs possessing polyethylene links ended with an iodine atom (TTF-(CH2)(n)-I). Two different methods are proposed: (i) via the carbon charge considered as a polynucleophile (at carbon surface polarized at E

International audience; The unusual synthesis of the dimeric dithiolene complex [PPh3)Pd(ethylene-1,2-dithiolate)](2) (1), containing the simplest dithiolene ligand, has been achieved through the reaction between tetrathiafulvalene (TTF) and Pd(PPh3)(4). The complex shows a folded structure in the solid state, according to single crystal X-ray analysis performed on crystals grown from two different system solvents and conditions, with a central [Pd2S2] ring folded about the S center dot center dot center dot S hinge by 67.9 degrees. The optimized geometry at the DFT level is in excellent agreement with the experimental structure. Moreover, TD-DFT calculations allowed the assignment of the low energy band arising at 576 nm to the HOMO - LUMO transition, between frontier orbitals having mixed metal and dithiolene character. (C) 2012 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.

The control of the loss mechanism in a dye sensitised solar cell (DSSC) via recombination of the injected electron with the oxidised dye was investigated by incorporating a redox-active ligand, 6,7-bis(methylthio)tetrathiafulvalene dithiolate (TTF(SMe)2), into a ruthenium bipyridyl dye. A series of dyes with general formula [Ru(4,4'-R-bpy)2(TTF(SMe)2], where R = H, CO2Et and CO2H, were synthesised and characterised using electrochemistry, absorption and emission spectroscopy, spectroelectrochemistry and hybrid-DFT calculations. In addition, the performance of the acid derivative in a DSSC was investigated using IV measurements, as well as transient absorption spectroscopy. These complexes showed significant TTF-ligand character to the HOMO orbital, as deduced by spectroelectrochemical, emission and computational studies. Upon adsorption of the acid derivative to TiO2 a long-lived charge-separated state of 20 ms was observed via transient absorption spectroscopy. Despite this long-lived charge-separated state, the dye yielded extremely low DSSC efficiencies, attributed to the poor regeneration of the neutral dye by iodide. As a result, the complex forms a novel long-lived charge separated state that persists even under working solar cell electrolyte conditions.

International audience; The noncentrosymmetric p-carboxybenzenesulfonate anion afforded, in electro-oxidation experiments with bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF), the low-gap semiconductor (room-temperature conductivity: 18 S cm–1) mixed-valency salt BEDT-TTF2[O3S-C6H4-CO2H], which is noncentrosymmetric due to head-to-tail arrangement of the anions, whereas EDT-TTF-CONHMe (EDT-TTF = ethylenedithiotetrathiafulvalene) afforded the fully oxidized centrosymmetric salt [EDT-TTF-CONHMe+][HO2C-C6H4-SO3–] in which the driving force for the crystal packing is the existence of strong hydrogen-bonding interactions between the anions and the amido groups of the cations.

International audience; The single crystal X-ray structure of the precursor dithiomethyl-tetrathiafulvalene (MeS)2TTF is reported, together with theoretical calculations at DFT level, which afforded two energy minima corresponding to cis and trans orientations of the thiomethyl substituents. The bis(tetrathiafulvalene) reaction of this TTF derivative followed by the reaction with phenyldichlorophosphine provides a new rigid bis(tetrathiafulvalene [TTF]) containing a 1,4-dihydro-1,4-diphosphinine ring between the two redox active units. Its solid-state structure, determined by single crystal X-ray diffraction analysis, shows the coexistence of both cis and trans isomers. Cyclic voltammetry measurements are in accordance with the existence of a communication between the two TTFs, as illustrated by the splitting of the oxidation waves.

Since the first reports more than a half-century ago, interest in self-assembled monolayers (SAMs) on metal surfaces has increased almost exponentially. At present, such supported SAMs are used for numerous applications, ranging from metallurgy—wherein the surface properties, such as conductivity, wettability, corrosion resistance, and etching resistance, are modified—to the preparation of sensors and materials for use in separations. In fact, the use of SAMs is now recognized as offering a convenient, flexible, and simple way to tailor the interfacial properties of metals. This is because the spontaneous organization and absorption of molecules on metal, metal oxide, or semiconducting surfaces often creates highly ordered systems with well-defined dimensions on the nanoscale. During the last decade, increasing attention has been dedicated to the design and elaboration of SAMs that integrate a molecular or ionic receptor unit with a transducer element so as to create sensing devices for environmental or biologic purposes. If a redox-active element is incorporated into the monolayer or the guest, the recognition event can be followed by cyclic voltammetry (CV). In other cases, the monitoring can be completed by using impedance spectroscopic measurements. Although, cation (generally metallic ions) recognition using SAMs is well documented, and several systems that exhibit both excellent selectivity and sensitivity have been described in the literature, much less work on anion recognition by using SAMs has been reported, perhaps reflecting the fact that anions have variable sizes and shapes and exhibit strong solvation in most solvents. The first anion recognition SAM systems were reported by Astruc et al. and involved the use of ferrocene derivatives for dihydrogenophosphate anion detection. More recently, Echegoyen et al. described SAMs for use in acetate anion recognition. Although these systems are very selective, their sensitivity is relatively low and the limits of detection do not reach the sub-millimolar scale. Calix[4]pyrrole and its derivatives have been extensively studied in the search for chemosensors capable of recognizing specific chemical species, with a number of optically active calix[4]pyrrole-based sensors having now been reported. Some of us have recently described the first fully successful examples of electrochemically active sensors based on calix[4]pyrroles; these were prepared by attaching one, two, or four redox-active tetrathiafulvalene (TTF) units directly to the calix[4]pyrrole platform so as to produce receptors with enhanced binding affinities toward anions as compared to the parent meso-octamethyl calix[4]pyrrole. In the case of the mono-TTF calix[4]pyrrole, we observed selectivity between the chloride anion (Ka= 2900m ) and the bromide anion (Ka=96m ) in CH2Cl2 solution. This success has led us to consider that TTF calix[4]pyrroles could be used to create anion-sensing SAMs. These kinds of receptors are attractive in this regard because they incorporate within one molecular framework both pyrrolebased anion recognition and TTF-derived transducer subACHTUNGTRENNUNGunits. We wish to report here that such SAMs may be prepared and that they are effective for chloride anion recognition at the sub-millimolar level, thus providing a sensitivity that differs dramatically from previously reported systems. [a] L. G. Jensen, Dr. K. A. Nielsen, Prof. J. O. Jeppesen Department of Physics and Chemistry University of Southern Denmark Campusvej 55, DK-5230, Odense M (Denmark) Fax: (+45)6615-8780 E-mail : joj@ifk.sdu.dk Homepage: http://www.jojgroup.sdu.dk [b] Dr. T. Breton, Prof. Dr. E. Levillain, Dr. L. Sanguinet Universit d’Angers—CNRS 2 boulevard Lavoisier 49045, Angers Cedex (France) E-mail : eric.levillain@iniv-angers.fr lionel.sanguinet@univ-angers.fr [c] Prof. J. L. Sessler Department of Chemistry and Biochemistry The University of Texas at Austin 1 University Station, A5300, Austin, TX 78712-0165 (USA) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.200901394.

International audience; The neutral meso-octamethylporphyrinogen derivative, tetraTTF-calix[4]pyrrole 1 (TTF=tetrathiafulvalene), acts as a multi-faceted receptor in that it interacts with an assortment of different guests in different ways. The conformation of receptor 1 can be reversibly switched between the 1,3-alternate conformation (i.e., 1, Fig.1) and the cone conformation (i.e., 1·Cl−, Fig.2) by the repetitive addition of chloride and sodium ions. In this paper, the results of detailed and systematic complexation studies involving both 1 and its chloride-bound complex, 1·Cl−, with a variety of guests are described. Receptor 1 binds quasi-planar nitroaromatic guests in its 1,3-alternate conformation, while release of these guests takes place upon addition of chloride anions. On the other hand, spherical fullerene guests are strongly bound by 1·Cl−. Finally, it was found that a bidentate guest, consisting of a quasi-planar 2,5,7-trinitro-9-dicyanomethylenefluorene moiety tethered to a spherical C60 fullerene, could be recognized by receptor 1 in either its 1,3-alternate or its chloride-bound cone conformation, albeit through very different binding modes.

International audience; The synthesis and characterization of two ortho-dimethyltetrathiafulvalene (o-DMTTF)-based rigid dimers containing dimethylsilicon (Me(2)Si) or dimethylgermanium (Me(2)Ge) linkers are described. Single-crystal X-ray analysis reveals planar geometry for the central 1,4-disilicon or 1,4-digermanium six-membered rings. DFT calculations provide optimized conformations in agreement with the experimental ones, and also emphasize the role of the heteroatomic linkers in the conjugation between the two redox active units. Cyclic voltammetry measurements show sequential oxidation into radical cation, and then dication species. Solution EPR measurements on the radical-cation species indicate full delocalization of the unpaired electron over both electroactive TTF units, with an associated coupling of 0.42 G with twelve equivalent protons. DFT calculations afford fully planar geometry for the radical-cation species and confirm the experimental isotropic coupling constant. Single-crystal X-ray analyses of two charge-transfer compounds obtained upon chemical oxidation, formulated as [(Me(2)Si)(2)(o-DMTTF)(2)].1/2[TCNQ].1/2[TCNQF(4)] and [(Me(2)Ge)(2)(o-DMTTF)(2)].[TCNQ], demonstrate the occurrence of genuine mixed-valence radical-cation species, as well as a three-dimensional network of short S...S intermolecular contacts. Temperature-dependent conductivity measurements demonstrate semiconducting behavior for both charge-transfer compounds, with an increase of the absolute value of the conductivity upon applying external pressure. Band structure calculations reveal peculiar pseudo-two-dimensional electronic structures, also confirming electronic interactions through SiMe(2) and GeMe(2) bridges.

C 5 H 4 O 2 S 3 ,monoclinic, P 12 1 / c 1(no.14), a =3.9797(1)A, b =6.0394(2)A, c =31.1165(6)A, =91.868(1)°, V =747.5A 3 , Z =4, R gt (F) =0.119, wR ref (F 2 ) =0.324, T =200K. Source of material In the literature 4-methoxycarbonyl-1,3-dithiole-2-thione wasobtainedinthreesteps[1].Inthepresentone-potsynthesistheti-tlecompoundwasobtainedundersolventfreeconditionscata-lyzedbypotassiumcyanideinthepresenceofsilicaassolidsupportat200°C(85%yield).0.2mmolof4,5-bis(carbonyl-methoxy)-1,3-dithiole-2-thione,0.4mmolofpotassiumcyanideand0.2gofsilicaweremixedinamortar.Thispowderwasheatedfor1hat200°C.Thecolorofthemixturewasturnedfromyellowtolightbrown.Thepurecompoundwasobtainedbyfiltrationofthesolutionindichloromethane,followedbyevaporationofsol-ventandpreparativechromatographyoversilicagel.TheproductwascharacterizedbyIR, 1 HNMR,and 13 CNMRspectroscopy. Experimental details TheX-rayreflectionswereratherbroadanddiffuse,butthedataturnedouttobeuseable.Allhydrogenatomsweretreatedusingappropriateridingmodels.Thebadqualityofthecrystalsandthedatasetwerethereasonsforthelarge

International audience; By using two different routes, series of new bis- and tris-TTF, containing in their linker function(s) able to generate supplementary interactions in the resulting materials, have been prepared. The first route based on deprotection-realkylation strategy allowed to introduce alcohol and ketone functions. The second way, using acid chloride and hydroxy-TTF, allowed to include ester function in the linker. The electron-donating ability of this series of TTFs has been determined by CV and by SQW.

The advantages of organic field-effect transistors (OFETs), such as low cost, flexibility and large-area fabrication, have recently attracted much attention due to their electronic applications. Practical transistors require high mobility, large on/off ratio, low threshold voltage and high stability. Development of new organic semiconductors is key to achieving these parameters. Recently, organic semiconductors have been synthesized showing comparable mobilities to amorphous-silicon-based FETs. These materials make OFETs more attractive and their applications have been attempted. New organic semiconductors resulting in high-performance FET devices are described here and the relationship between transistor characteristics and chemical structure is discussed.