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Mechanically interlocked molecules are a class of compounds used for controlling directional movement when barriers can be raised and lowered using external stimuli. Applied voltages can turn on redox states to alter electrostatic barriers but their use for directing motion requires knowledge of their impact on the kinetics. Herein, we make the first measurements on the movement of cyclobis(paraquat‐p‐phenylene) (CBPQT4+) across the radical‐cation state of monopyrrolotetrathiafulvalene (MPTTF) in a [2]rotaxane using variable scan‐rate electrochemistry. The [2]rotaxane is designed in a way that directs CBPQT4+ to a high‐energy co‐conformation upon oxidation of MPTTF to either the radical cation (MPTTF⋅+) or the dication (MPTTF2+). 1H NMR spectroscopic investigations carried out in acetonitrile at 298 K showed direct interconversion to the thermodynamically more stable ground‐state co‐conformation with CBPQT4+ moving across the oxidized MPTTF2+ electrostatic barrier. The electrochemical studies revealed that interconversion takes place by movement of CBPQT4+ across both the MPTTF•+ (19.3 kcal mol−1) and MPTTF2+ (18.7 kcal mol−1) barriers. The outcome of our studies shows that MPTTF has three accessible redox states that can be used to kinetically control the movement of the ring component in mechanically interlocked molecules. [ABSTRACT FROM AUTHOR]

Calix[4]arenes and calix[4]resorcinarenes are well‐known macrocyclic hosts that can be tailored to bind guests of very different natures, including anions, cations, and various neutral molecules. The molecular architectures of the hosts can be altered in many ways: by attaching polar or hydrophilic groups, extending inner cavities with enlarged aromatic side walls, and adding H‐bonding sites to promote the formation of molecular capsules. The attachment of different types of redox‐active moieties renders calix[4]arene and calix[4]resorcinarene derivatives electrochemically active, enabling them to either control the guest‐binding properties of the receptors or be used as electrochemical sensors. This review will focus on calix[4]arene and calix[4]resorcinarene macrocyclic hosts with appended redox‐active groups, such as ferrocene, tetrathiafulvalene, and quinone. We will discuss molecular receptors that can serve as redox sensors for cations or electron‐deficient molecules or can bind and release their guests controlled by redox or electrochemical stimuli. [ABSTRACT FROM AUTHOR]

An electrochemical study using the cyclic voltammetry method was carried out on some previously prepared merocyanines salts, namely thiazolideniumsulfonate salts 5a-b, and thiazolidenium chloride salts 6a-b, and merocarbocyanines salts, namely alkylidenthiazolidenium sulfonate salt 5c, and alkylidenthiazolidenium chloride salt 6c. These salts are transformed by dimerization in situ in a voltammetric cell into tetrathiatetraazafulvalenes (TTTAFs) 7a-b, 7’a-b, 8c, and 8'c supposed to be π-electron donor molecules due to the existing conjugation in their structure. The structure of all new chemically synthesized molecules was confirmed by IR, 1H-NMR, 13C-NMR, and MS. The transformation of salts into TTTAF was confirmed by a reversible voltammogram curve and the variation of observed potentials.

An approach for the lower rim modification of the calix[4]arene‐based molecular tweezes with monopyrrolo‐tetrathiafulvalene (MPTTF) arms attached to the upper rim of calixarenes is described. First, calixarene‐MPTTF conjugates with free hydroxyl on the lower rim are synthesized using the Ullmann reaction, then hydroxyl groups are substituted by propargyl groups, which can be used for further modification by the click reaction. The new calixarene‐TTF derivatives displayed reversible redox processes, as well as demonstrated binding affinity for electron‐deficient molecular guests such as tetracyanoquinodimethane. The described synthetic approach will be used for the modular synthesis of molecular receptors tailored for specific applications. [ABSTRACT FROM AUTHOR]

The synthesis and characterisation of tetrasubstituted tetrathiafulvalenes (TTFs) 1a–1c, which bear photoresponsive 4ʹ-cyanoazobenzenyl units, are described. These units were linked to the TTF core through spacers of different lengths. All synthesised compounds displayed mesogenic phases over a wide temperature range and no crystallisation, but vitrified to form glassy mesogens during cooling from the isotropic melt. Compound 1a with a short spacer (n = 6) exhibited enantiotropic nematic and smectic A mesophases. In contrast, compound 1b showed monotropic smectic A and oblique columnar phases. However, compound 1c with the longest spacer (n = 10) only possessed an oblique columnar phase. The results for this compound series showed that the molecular packing pattern depended on the spacer length and that cool-crystallisation was observed upon further heating. Furthermore, cyclic voltammetry and impedance tests confirmed that compound 1a has potential applications in organic semiconductor materials. A new series of compounds derived from heterocycle TTF was successfully designed and synthesised using simple synthetic methods. All compounds formed glassy mesogens with an above-ambient glass transition temperature during cooling from the isotropic melt. With increasing spacer length, the self-assembled structures changed from Lam to Colo. These TTF‐based LCs, in combination with good electron-donating properties and the inherent optoelectronic properties of azobenzene, might be attractive new candidates for organic optoelectronic devices. [ABSTRACT FROM AUTHOR]

A new tetrathiafulvalene (TTF) derivative is synthesized, which is substituted with two phenoxy radicals on one 1,3‐dithiole ring, and may have either open‐shell diradical or closed‐shell extended‐quinoidal ground states. X‐ray single crystal analysis and NMR measurements prove that this molecule has a closed‐shell extended quinoidal structure both in the solid state and in solution. DFT calculations show the donor–acceptor electronic properties of this molecule with a well‐separated HOMO–LUMO distribution and a small HOMO–LUMO energy gap. Because of this donor–acceptor character, this molecule gives both the dication and the dianion species by electrochemical oxidation and reduction. Furthermore, during the redox process between the neutral and dication states, this molecule exhibits unique changes in the cyclic voltammogram upon repeating the cycles or varying the scan rate. The observed electrochemical behavior is explained by the conformational changes in the electrochemically generated species, thus indicating that this molecule is classified as a dynamic redox system. [ABSTRACT FROM AUTHOR]

Halogen bonding (XB) interactions are investigated in cation radical salts of bis(methylthio)‐5,5'‐diiodotetrathiafulvalene (1). Electrocrystallization of 1 in the presence of Bu4NCl 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 (Vs,max=87.2 kcal/mol), as strong as with the iodine atoms (Vs,max=87.9 kcal/mol). The radical cations form weakly dimerized stacks, as confirmed by the variable‐temperature magnetic susceptibility and the weak conductivity (4.8×10−5 S cm−1). [ABSTRACT FROM AUTHOR]

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, as well as strong intermolecular interactions, are important prerequisites to account for the high electronic conduction in the solid state and the 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 Minireview, 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. [ABSTRACT FROM AUTHOR]

New crystalline salts (BEDT-TTF +){FeIII(CN) 2 Pc}−·C 6 H 4 Cl 2 (1) and (DB-TTF +) {FeIII(CN) 2 Pc}−·C 6 H 4 Cl 2 (2) contain closely packed 2D layers composed of the {FeIII(CN) 2 Pc}− anions and manifest antiferromagnetic Fe-Cation and Fe-Fe couplings. Smaller DB-TTF + radical cation provides denser packing and stronger couplings. Salt (DB-TTF0) 2 {Cryptand(K+)}{FeIII(CN) 2 Pc}− (3) with neutral DB-TTF shows only weak antiferromagnetic coupling of −1.6 cm−1. [Display omitted] • Salts tetrathiafulvalenes with dicyanoiron(III) phthalocyanine anions. Electrooxidation of bis(ethylenedithio)tetrathiafulvelene (BEDT-TTF) and dibenzotetrathiafulvelene (DB-TTF) in the presence of dicyanoiron(II) phthalocyanine (Pc) dianions in form of the {Cryptand(K+)} 2 {FeII(CN) 2 Pc}2− salt has been studied in o -dichlorobenzene and acetonitrile solutions (where Cryptand is cryptand[2.2.2]). Initially iron(II) is oxidized to iron(III) and after that tetrathiafulvelenes are oxidized forming crystalline salts (BEDT-TTF +){FeIII(CN) 2 Pc}−·C 6 H 4 Cl 2 (1) and (DB-TTF +){FeIII(CN) 2 Pc}−·C 6 H 4 Cl 2 (2). Both salts contain closely packed 2D layers composed of the {FeIII(CN) 2 Pc}− anions and cationic layers containing solvent molecules. Since cations cannot partially oxidize Pc in these salts, two S = 1/2 spins are positioned on FeIII and the cations. The χ M T values are 0.90 and 0.87 emu·K/mol per formula unit at 300 K. Antiferromagnetic coupling of spins is observed in 1 and 2 due to both Fe-Cation coupling of −0.4 and −3.5 cm−1 and Fe-Fe couplings of −3.5 and −7.9 cm−1, respectively. Due to its smaller size of DB-TTF+, complex 2 has denser packing of the components and shows stronger exchange couplings. An unusual compound forms when DB-TTF and {FeII(CN) 2 Pc}2− are oxidized together in acetonitrile: (DB-TTF0) 2 {Cryptand(K+)}{FeIII(CN) 2 Pc}− (3) where charges on DB-TTF and Fe are closer to zero and +3, respectively. The {FeIII(CN) 2 Pc}− anions form layers in 3 among which chains with short C,N...C,N contacts between Pc can be outlined. Only weak intermolecular antiferromagnetic coupling is manifested in 3 with estimated zJ value of −1.6 cm−1. [ABSTRACT FROM AUTHOR]

A series of organic–inorganic hybrid clusters comprising thioarylated tetrathiafulvalene derivatives (A‐S‐TTFs) and Keggin‐type polyoxometalates have been prepared via proton‐induced intermolecular charge transfer or electrochemical oxidation methods, and their structural features have been intensively studied by X‐ray diffraction. The generation of co‐crystals occurs due to the flexible structure of the A‐S‐TTF and its electrostatic interaction with the polyoxometalate anions. The complexes can be divided into three types, i.e., type I, type II, and type III, which have organic/inorganic ratios of 3:1, 2:1, and 1:1, respectively. Multiple intermolecular interactions are observed between the organic and inorganic moieties, which stabilize the structures of the resulting hybrid clusters. In the clusters, Ar‐S‐TTFs are oxidized into radical cations [except in complex (TTF4)·(PMA)·(TBA), where TTF4 is presented as a +2 cation]. There are two factors affecting the packing styles and compositions of the hybrid clusters: 1) valence state of the Ar‐S‐TTF and 2) volume of the aryl groups thereon. [ABSTRACT FROM AUTHOR]

Tris‐fused π‐electron donors composed of two tetrathiafulvalenes (TTFs) and one extended TTF with anthraquinoid spacer (3) were successfully synthesized. The cyclic voltammograms of the tetrakis(n‐hexylthio)‐ and bis(ethylenedioxy) derivatives 3c and 3d consisted of three‐pairs of two‐electron redox waves. Spectroelectrochemitry of 3c indicated that two positive charges in 3c2+ are located mainly on the central extended TTF moiety. Coin‐type cells composed of the positive electrodes incorporating the unsubstituted‐3 (3a) and 3d showed the discharge capacities of 192 and 160 mAh g–1, respectively, in which six electrons per molecule are involved. [ABSTRACT FROM AUTHOR]

The enantiopure dimethyl-ethylenedithio-tetrathiafulvalene (DM-EDT-TTF) donor exists as biaxial (ax, ax) and biequatorial (eq, eq) conformers in equilibrium. DFT calculations combined with free energy surface (FES) analysis establish that the (ax, ax) form is more stable by ?0.7 kcal·mol–1 than the (eq, eq) one and that the inter-conversion process involves a sequential conformational change through a boat type (ax, eq) conformer with an activation energy of ?3 kcal.mol–1. TD-DFT calculations show similar, but opposite in sign, CD bands for the two conformers. A Boltzmann type average of the two CD curves, corresponding to a ratio of three (ax, ax) for one (eq, eq) conformers in equilibrium in solution, provides an excellent agreement with the experimental curve.

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.

Tetrathiafulvalene (TTF) has been one of the most studied compounds, since the discovery of electrical conductivity as a charge‐transfer complex in combination with tetracyano‐p‐quinodimethane (TCNQ) in 1973. In 2004, TTF was realized in a new light as an innate semiconductor material, as well as conductor and superconductor material. Because of the ready modification of its core skeleton and better solubility than that of acene compounds, many TTF derivatives have been reported to attain better charge‐carrier mobility for field‐effect transistor devices. Considering the high charge‐carrier mobility of acene and TTF derivatives, annulation of the acene and TTF moieties is expected to improve the charge‐carrier mobilities. This Minireview focuses on the syntheses, crystal structures, and electronic properties of state‐of‐the‐art π‐extended TTF derivatives, based on the history of the development of TTF derivatives. The relationship between the packing structure and charge‐carrier mobilities is also discussed. Expanding the range: New tetrathiafulvalene compounds annulated with acenes, electron‐withdrawing imides, quinozalines, benzothiadiazole, and imides (see figure) are reviewed as organic semiconducting materials. [ABSTRACT FROM AUTHOR]

We present a density functional theory (DFT) study on the reactivity of bis and tris (1,3-dithiole) TTF 1-4 by using B3LYP/6-31G (d,p) level. The possible electrophile and nucleophile attacking sites of the title compounds is identified using MEP surface plot study. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gaps were calculated to explain the frontier molecular orbitals and to predict the quantum chemical descriptors. Local reactivity properties have been investigated using average local ionization energies and Fukui functions. Natural Bond Orbital analysis was computed and possible transitions were correlated with the electronic transitions. The calculated first hyperpolarizability (β0) of bis and tris (1,3-dithiole) TTF molecules, indicates that investigated molecules might have not the NLO applications. [ABSTRACT FROM AUTHOR]

This review article focuses on the development of coordination polymers based on tetrathiafulvalene and its derivatives. We aim to demonstrate novel opportunities for these coordination polymers in terms of their architectures and potential applications. The review is presented in five general sections according to the type of coordinating functional group in the organic linkers. Synthetic approaches, structural analyses, as well as physical and chemical properties are presented for each example. Valuable potential applications and perspectives for these novel materials are also discussed. [ABSTRACT FROM AUTHOR]

A major challenge is the development of multifunctional metal-organic frameworks (MOFs), wherein magnetic and electronic functionality can be controlled simultaneously. Herein, we rationally construct two 3D MOFs by introducing the redox active ligand tetra(4-pyridyl)tetrathiafulvalene (TTF(py)4) and spin-crossover FeII centers. The materials exhibit redox activity, in addition to thermally and photo-induced spin crossover (SCO). A crystal-to-crystal transformation induced by I2 doping has also been observed and the resulting intercalated structure determined. The conductivity could be significantly enhanced (up to 3 orders of magnitude) by modulating the electronic state of the framework via oxidative doping; SCO behavior was also modified and the photo-magnetic behavior was switched off. This work provides a new strategy to tune the spin state and conductivity of framework materials through guest-induced redox-state switching. [ABSTRACT FROM AUTHOR]

Tetrathiafulvalenes (TTFs)1, redox-controllable electron-rich heterocycles, were employed as building blocks for the construction of molecular receptors and switchable macrocycles. Redox-active calixarene-based molecular receptors2with various substituents R1on the tetrathiafulvalene groups and rigid or flexible attachment of TTF units to the backbone have been prepared using modular construction approach. The addition of planar electron-deficient guests to receptor solutions leads to formation of deeply-colored charge-transfer complexes with high binding constants reaching 2.5 × 105 M−1. TTF substituents display the strong influence on the binding constants and charge transfer intensity. By the synthesis of macrocyclic tetrathiafulvalene-azobenzene (TTF-AB) conjugates3, we have shown the first example of photochemically controlled macrocyclization, in which the formation of smaller 1 + 1 and larger 2 + 2 cyclization products can be modulated by photoisomerization of one of the reactants. The oxidation potential of the small, structurally rigid, TTF-AB macrocycle is found to depend on the conformation of the AB moiety. [ABSTRACT FROM PUBLISHER]

Tetrathiafulvalenes (TTFs) are popular building blocks on the scene of supramolecular chemistry, where they play various roles ranging from electron rich guest moieties in interlocked supramolecular architectures to structural elements of ion sensors. In this review, we discuss so far rather neglected role of TTFs as active elements of binding sites in molecular receptors. We consider several recent design concepts of molecular receptors with architectures of molecular tweezers, macrocycles, and metal-coordinated cages that contain two or more TTF, extended TTF, or pyrrolo-TTF moieties. High affinity to electron-deficient guests and redox activity allowed their use for the construction of functional supramolecular materials and sensors, as well as pave the way for other practical applications. [ABSTRACT FROM AUTHOR]

The synthesis of N-heterocyclic carbene (NHC)-cyclic (alkyl)(amino) carbene (CAAC) heterodimers is presented. As the free carbenes do not react together in solution, the synthetic approach involves the addition of a free NHC to a cyclic iminium salt, which results in the formation of the protonated heterodimer. Subsequent deprotonation leads to the isolation of the corresponding mixed Wanzlick dimers. One- and two-electron oxidations of these triazaolefins result in the formation of stable cationic radicals and bis(cations), respectively, which have been isolated and fully characterized. Cyclic voltammetry, UV/Vis spectroscopy, spin density, and DFT calculations suggest that these heterodimers feature complementary electronic properties to tetrathiafulvalenes (TTFs). [ABSTRACT FROM AUTHOR]

Tetrathiafulvalenes (TTFs) are an appealing class of organic small molecules giving rise to some of the highest performing active materials reported for organic field effect transistors (OFETs). Because they can be easily chemically modified, TTF-derivatives are ideal candidates to perform molecule-property correlation studies and, especially, to elucidate the impact of molecular and crystal engineering on device performance. A brief introduction into the state-of-the-art of the field-effect mobility values achieved with TTF derivatives employing different fabrication techniques is provided. Following, structure-performance relationships are discussed, including polymorphism, a phenomenon which is crucial to control for ensuring device reproducibility. It is also shown that chemical modification of TTFs has a strong influence on the electronic structure of these materials, affecting their stability as well as the nature of the generated charge carriers, leading to devices with p-channel, n-channel, or even ambipolar behaviour. TTFs have also shown promise in other applications, such as phototransistors, sensors, or as dopants or components of organic metal charge transfer salts used as source-drain contacts. Overall, TTFs are appealing building blocks in organic electronics, not only because they can be tailored to perform fundamental studies, but also because they offer a wide spectrum of potential applications. [ABSTRACT FROM AUTHOR]

In this work we have been calculated global and local DFT reactivity descriptors for some p-aminophenyl tetrathiafulvalenes such as: the ionization potential (I), electron affinity (A), electronegativity (x), electrophilicity (ω), and hardness (η) have been calculated using density functional theory (DFT) approach with B3LYP/6-31G(d,p) level of theory. The plots of frontier molecular orbital and molecular electrostatic potential (MESP) have been demonstrated. The chemometric methods PCA and HCA were employed to find the subset of variables that could correctly classify the compounds according to their reactivity. [ABSTRACT FROM AUTHOR]

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 [Re6S6Clg]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. [ABSTRACT FROM AUTHOR]

Two new π-conjugated pyridine-based tetrathiafulvalene derivatives, 2-(2- (4,5-bis(methylthio)-1,3-dithiol-2-ylidene)-6-phenyl-[1,3]dithiolo[4,5-b][1,4]dithiin-5-yl)pyridine (2a) and 3-(2-(4,5-bis(methylthio)-1,3-dithiol-2-ylidene)-6-(pyridin-2-yl) -[1,3]dithiolo[4,5-b][1,4]dithiin-5-yl)quinoline (2b), have been synthesized and characterized by 1H NMR, elemental analysis and mass spectroscopies. The compound 2a has also been studied by X-ray crystallography and theoretical calculations using density functional theory (DFT) framework with B3LYP/6-311+G(d,p) level of theory. Its crystal structure is triclinic system, space group P1 - . The unit cell dimensions are: a = 8.813(3) Å, b = 11.082(3) Å, c = 12.620(4) Å, α = 88.805(5)°, β = 80.440(5)°, γ = 75.680(5)°, V = 1177.3(6) ų, Z = 2. The molecule exhibits one classical C-H...N intermolecular hydrogen bonds, two kinds of short intermolecular S...S interactions and two types of C-H...π supramolecular interactions. [ABSTRACT FROM AUTHOR]

A series of mono- (MPTTF) and bis(pyrrolo)tetrathiafulvalene (BPTTF) derivatives tethered to one or two C60 moieties was synthesized and characterized. The synthetic strategy for these dumbbell-shaped compounds was based on a 1,3-dipolar cycloaddition reaction between aldehyde-functionalized MPTTF/BPTTF derivatives, two different tailor-made amino acids, and C60. Electronic communication between the MPTTF/BPTTF units and the C60 moieties was studied by a variety of techniques including cyclic voltammetry and absorption spectroscopy. These solution-based studies indicated no observable electronic communication between the MPTTF/BPTTF units and the C60 moieties. In addition, femtosecond and nanosecond transient absorption spectroscopy revealed, rather surprisingly, that no charge transfer from the MPTTF/BPTTF units to the C60 moieties takes place on excitation of the fullerene moiety. Finally, it was shown that the MPTTF-C60 and C60-BPTTF-C60 dyad and triad molecules formed self-assembled monolayers on a Au(111) surface by anchoring to C60. [ABSTRACT FROM AUTHOR]

Herein we report the synthesis of several calix[4]arene derivatives with tetrathiafulvalene bridges at the upper rim. Calix[4]arene-tetrathiafulvalene (TTF) conjugates4a–d, fixed inconeconformation and comprising two smaller 1,2-bridges, were prepared by cyclisation of tetrakis-chloromethylated calix[4]arene1with 2,3-dithiolates of TTFs. Larger calix[4]arene-TTF macrocycles14and15, also inconeconformation, contain 1,3-bridges and were synthesised by cyclisation of 2,6- and 2,7-dithiolates of TTFs with bis-bromomethylated calix[4]arene7. Redox properties of new calix[4]arene-TTF conjugates were characterised using cyclic voltammetry. [ABSTRACT FROM AUTHOR]

The synthesis of new unsymmetrically benzene-fused bis (tetrathiafulvalene) has been carried out by a cross-coupling reaction of the respective 4,5-dialkyl-1,3-dithiole- 2-selenone 6-9 with 2-(4-(p-nitrophenyl)-1,3-dithiole-2-ylidene)-1,3,5,7-tetrathia-sindacene- 6-one 5 prepared by olefination of 4-(p-nitrophenyl)-1,3-dithiole-2-selenone 3 and 1,3,5,7-tetrathia-s-indacene-2,6-dione 4. The conversion of the nitro moiety 10a-d to amino 11a-d then dibenzylamine 12a-d groups respectively used reduction and alkylation methods. The electron donor ability of these new compounds has been measured by cyclic voltammetry (CV) technique. Charge transfer complexes with tetracyanoquino-dimethane (TCNQ) were prepared by chemical redox reactions. The complexes have been proven to give conducting materials. [ABSTRACT FROM AUTHOR]

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.

Two tetrathiafulvalene (TTF) functionalized 2,2′:6′,2″-terpyridine derivatives, 4′-tetrathiafulvalene-2,2′:6′,2″-terpyridine (L1) and 6,6″-dimethyl-4′-tetrathiafulvalene-2,2′:6′,2″-terpyridine (L2), were synthesized and characterized. Based on L1 and L2, four electrochemically active TTF-containing iron(II) complexes, [FeII(L1)2][ClO4]2 ( 1), [FeII(L1 ·+)2][ClO4]4 ( 2), [FeII(L1)2][CF3SO3]2 ( 3) and [FeII(L2)2][ClO4]2 ( 4), were successfully obtained. The preparation, spectroscopic and electrochemical properties of these new compounds as well as the crystal structures of complexes 1, 3 and 4 are described. Magnetic studies on 4 (with the ligand L2) suggest that the FeII ion is in the high-spin state. Complex 2 was isolated as an interesting and stable open-shell substance, and the free spin is mainly associated with the TTF radicals, as indicated by EPR, UV/Vis spectra, electrochemical analysis, spectroelectrochemical measurements and XPS spectra. After the oxidation and the formation of the radical cation, the electrical conductivity of 2 is almost 3 orders of magnitude higher than that of 1. DFT and TDDFT calculations provided insight into interpreting the electronic properties of complex 1 and its oxidized states. [ABSTRACT FROM AUTHOR]

Electroactive fused ethylenedithiotetrathiafulvalene[4]helicene and -[6]helicenes have been synthesized through a strategy that involved the preparation of 2,3-dibromo-helicene derivatives as intermediates. The dihedral angles between the terminal helicenes, as determined by single-crystal X-ray analysis, are 22.7° and 50.7° for the [4]helicene and [6]helicene, respectively. Their solid-state architectures show interplay between S⋅⋅⋅S and π⋅⋅⋅π intermolecular interactions. The chiroptical properties of the enantiopure EDTTTF[6]helicene derivatives have been investigated and supported by TDDFT calculations. Remarkable redox switching of the circular dichroism (CD) signal between the neutral and radical-cation species has been achieved. [ABSTRACT FROM AUTHOR]

Spectrophotometry was shown to be applicable for the determination of compositions of the ET and BEDO-TTF tetrathiafulvalenes-based salts, which in the spectra have the overlapping absorption regions of the radical-cation and the non-oxidized forms. A procedure for the determination of the molar absorption coefficients of the radical-cation form was developed. Mathematical expressions for the determination of the tetrathiafulvalenes oxidation states and the counterion molecular weight were obtained. The application of this method is limited by the low solubility of the salts with the doubly charged anions and the bromide anion because of the reduction of ET to ET upon a prolonged dissolution of such salts. [ABSTRACT FROM AUTHOR]

Abstract: Organic π-donors such as tetrathiafulvalenes (TTF) substituted by primary alkyl iodides (RI) may react in contact with polarized glassy carbon at potentials more negative than −1V 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 <−1.7V) and (ii) via the catalytic coverage of carbon by Pd0 (at about −1V), using aprotic polar solvents such as acetonitrile, N,N-dimethylformamide, and propylene carbonate containing tetraalkylammonium salts. At very negative potentials, the cathodic charge of carbon is expected to generate nucleophiles while the use of palladium (used at an average surface concentration of 4×10−10 atomcm−2) may favour the formation of transient alkyl radicals. TTF layers are easily generated by these two methods and superficial concentrations were found to be high, up to 10×10−9 molcm−2. A similar grafting of TTFs was successfully achieved onto graphite. [Copyright &y& Elsevier]

A series of tetrathiafulvalene (TTF)-annulated porphyrins, and their corresponding ZnII complexes, have been synthesized. Detailed electrochemical, photophysical, and theoretical studies reveal the effects of intramolecular charge-transfer transitions that originate from the TTF fragments to the macrocyclic core. The incremental synthetic addition of TTF moieties to the porphyrin core makes the species more susceptible to these charge-transfer (CT) effects as evidenced by spectroscopic studies. On the other hand, regular positive shifts in the reduction signals are seen in the square-wave voltammograms as the number of TTF subunits increases. Structural studies that involve the tetrakis-substituted TTF-porphyrin (both free-base and ZnII complex) reveal only modest deviations from planarity. The effect of TTF substitution is thus ascribed to electronic overlap between annulated TTF subunits rather than steric effects. The directly linked thiafulvalene subunits function as both π acceptors as well as σ donors. Whereas σ donation accounts for the substituent-dependent charge-transfer transitions, it is the π-acceptor nature of the appended tetrathiafulvalene groups that dominates the redox chemistry. Interactions between the subunits are also reflected in the square-wave voltammograms. In the case of the free-base derivatives that bear multiple TTF subunits, the neighboring TTF units, as well as the TTF ⋅+ generated through one-electron oxidation, can interact with each other; this gives rise to multiple signals in the square-wave voltammograms. On the other hand, after metalation, the electronic communication between the separate TTF moieties becomes restricted and they act as separate redox centers under conditions of oxidation. Thus only two signals, which correspond to TTF .+ and TTF2+, are observed. The reduction potentials are also seen to shift towards more negative values after metalation, a finding that is considered to reflect an increased HOMO-LUMO gap. To probe the excited-state dynamics and internal CT character, transient absorption spectral studies were performed. These analyses revealed that all the TTF-porphyrins of this study display relatively short excited-state lifetimes, which range from 1 to 20 ps. This reflects a very fast decay to the ground state and is consistent with the proposed intramolecular charge-transfer effects inferred from the ground-state studies. Complementary DFT calculations provide a mechanistic rationale for the electron flow within the TTF-porphyrins and support the proposed intramolecular charge-transfer interactions and π-acceptor effects. [ABSTRACT FROM AUTHOR]

The article presents information regarding the rechargeable batteries by the use of Multifused Tetrathiafulvalene systems. It mentions that the Cobalt and nickel oxides are mostly used in lithium-ion rechargeable batteries for cathode active materials. It mentions that the organic molecular conductors could be used as active electrode materials as they are scarcely soluble in ordinary organic solvent.

Abstract: 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···S hinge by 67.9°. 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 576nm to the HOMO→LUMO transition, between frontier orbitals having mixed metal and dithiolene character. [Copyright &y& Elsevier]

Abstract: New amide functional tetrathiafulvalene ligands containing naphthyridine moiety (L 1 –L 3 ) were synthesized. Further coordination reactions of these ligands with Re(CO)5Cl afford three interesting rhenium tricarbonyl complexes, ClRe(CO)3(L). Crystal structures of ClRe(CO)3(L 1 ) (1) and ClRe(CO)3(L 2 ) (2) have been determined. Electrochemical and spectroscopic properties of all compounds are investigated. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and characterization of a new extended tetrathiafulvalene (TTF) dithiolene ligand substituted with alkyl pyridine groups, pyridylethylsulfanyltetrathiafulvalenedithiolene (pesdt2−), as well as the corresponding gold (III) complex [Au(pesdt)2]− obtained as a tetrabutylammonium salt are described. The oxidation potential of this complex is rather low and the paramagnetic neutral complex is obtained as an electrically insulating microcrystalline powder. [Copyright &y& Elsevier]

Abstract: Using the deprotection–realkylation methodology, a new electroactive tetrathiafulvalene-based bipyridine ligand, 5-[{2-[4,5-Bis(methylthio)-1,3-dithiol-2-ylidene]-5-(methylthio)-1,3-dithiol-4-yl}thio]-methyl-2,2′-bipyridine (L), has been synthesized. Reactions of the above ligand with Re(CO)5Br or Re(CO)5Cl afford the corresponding tricarbonyl rhenium(I) complexes ReL(CO)3X (X=Br, 1; X=Cl, 2), respectively. Crystal structures of 1 and 2 have been described. The absorption properties of these new compounds have been studied. Electrochemical measurements have been performed and TTF/TTF+•/TTF2+ redox processes are observed. [Copyright &y& Elsevier]

We have synthesized a series of oligodentate ligands, the structure of which consists of a central aromatic core and three or four tetrathiafulvalene-based arms. Their syntheses exploited a simple general protocol based on the reaction of a bromomethylated core with a thiolate generated in situ from an appropriate tetrathiafulvalene precursor. According to molecular modeling, proper positioning of the fulvalene arms over the central platform gives rise to an electron-rich cavity suitable for inclusion of spatial electron-deficient guests such as fullerenes. Graphical abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of novel upper rim calix[4]arene–tetrathiafulvalene conjugates 1a–d has been performed by bridging the tetrachloromethylated calix[4]arene derivative 4 with the corresponding tetrathiafulvalene-dithiolates. The cyclic voltammetry of 1a–d shows a two-step oxidation behavior, whereas NMR binding titrations showed their binding affinity to pyridinium salts. X-ray structure of 4 features calixarene fixed in the pinched cone conformation; its crystal packing is defined by the network of C–H···Cl weak hydrogen bonds. [Copyright &y& Elsevier]

Highly soluble bis-(2-cyanoethyl)-protected derivative (11) of monopyrrolo-tetrathiafulvalene containing a bulky 3,5-di-tert-butylbenzyl solubilizing group has been synthesized and characterized. It was successfully employed to prepare two aromatic conjugates of monopyrrolo-tetrathiafulvalenes (TTFs) and is proposed to be used for preparation of TTF-containing molecular tweezers. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]