Tetrathiafulvalene Units Research Articles

Effect of Metal Coordination on Photocurrent Response Properties of a Tetrathiafulvalene Organogel Film

Organic low molecular weight gelators with a tetrathiafulvalene (TTF) unit have received considerable attention because the formed gels usually exhibit redox active response and conducting or semiconducting properties. However, to our knowledge, metal coordination systems have not been reported for TTF-derived gels up to date. We have designed and synthesized a series of TTF derivatives with a diamide-diamino moiety that can coordinate to specific metal ions with square coordination geometry. Gelation properties and morphologies of the films prepared by the gelators in different hydrophobic solvents are characterized. The TTF derivative with a dodecyl group shows effective gelation properties, and electrodes with the organogel films are prepared. The effect of the Ni(II) and Cu(II) coordination on the photocurrent response property of the electrodes is examined. The metal square coordination significantly increases the photocurrent response. This gel system is the first metal coordination related TTF-gel-based photoelectric material. The mechanism of the metal coordination-improved photocurrent response property is discussed based on the crystal structural analysis and theoretical calculations.

Intramolecular electron transfer and charge delocalization in bistable donor–acceptor systems based on perchlorotriphenylmethyl radicals linked to ferrocene and tetrathiafulvalene units

A comparative analysis of the physicochemical properties of different donor–acceptor dyads, based on a perchlorotriphenylmethyl radical acceptor subunit linked through a vinylene π‐bridge to ferrocene derivatives (1–3) or a tetrathiafulvalene (4) donor subunit, is presented. Intramolecular electron transfer and charge delocalization of these donor–acceptor dyads are discussed on the basis of data obtained in solution by cyclic voltammetry, UV–Vis near‐infrared, and electron spin resonance spectroscopies. Bistability in the crystalline phase is also discussed on the basis of the results provided by X‐ray diffraction analysis and temperature‐dependent Mössbauer spectra. Copyright © 2014 John Wiley & Sons, Ltd.

Tetrathiafulvalene‐Based Macrocycles Formed by Radical Cation Dimerization: The Role of Intramolecular Hydrogen Bonding and Solvent

Compounds 1 a and 1 b were prepared by appending two tetrathiafulvalene (TTF) units to an aromatic amide segment that is driven by six or two intramolecular N-H⋅⋅⋅O hydrogen bonds to adopt a folded conformation. UV/Vis absorption experiments revealed that if the TTF units were oxidized to TTF(·+) radical cations, the two compounds could form a stable single molecular noncovalent macrocycle in less polar dichloromethane or dichloroethane or a bimolecular noncovalent macrocycle in a binary mixture of dichloromethane with a more polar solvent owing to remarkably enhanced dimerization of the TTF(·+) units. The stability of the (TTF(·+))2 dimer was evaluated through UV/Vis absorption, electron paramagnetic resonance, and cyclic voltammetry experiments and also by comparing the results with those of control compound 2. The results showed that introduction of the intramolecular hydrogen bonds played a crucial role in promoting the stability of the (TTF(·+))2 dimer and thus the noncovalent macrocyclization of the two backbones in both uni- and bimolecular manners.

Theoretical Investigations of Tetrathiafulvalene Derivative as Electron Donor in Organic Dye for Dye-Sensitized Solar Cells

To investigate the effect of a tetrathiafulvalene (TTF) unit on the photovoltaic properties of the corresponding dye sensitizer, a TTF-carbazole-based sensitizer, Dye 2, was designed; it was based on the framework of Dye 1. The geometries, electronic structures, and optical properties of Dye 1 and Dye 2 before and after binding to (TiO2)(9) clusters were investigated using density functional theory (DFT) and time-dependent DFT. The surface morphologies of the dyes on TiO2 (101) surfaces were simulated by periodic DFT calculations using the DMol(3) program. The calculated results showed that the introduction of TTF units into dyes could help to inhibit dye aggregation on the TiO2 surface; this is conducive to intramolecular charge-transfer transitions and significantly improves the light-harvesting ability. The calculated results demonstrate that the TTF unit is a very promising electron donor for improving the photovoltaic properties of organic dye sensitizers.

Self‐Assembly of Three‐Dimensional Supramolecular Polymers through Cooperative Tetrathiafulvalene Radical Cation Dimerization

The self-assembly of a new type of three-dimensional (3D) supramolecular polymers from tetrahedral monomers in both organic and aqueous media is described. We have designed and synthesized two tetraphenylmethane derivatives T1 and T2, both of which bear four tetrathiafulvalene (TTF) units. When the TTF units were oxidized to the radical cation TTF(.+) , their pre-organized tetrahedral arrangement remarkably enhanced their intermolecular dimerization, leading to the formation of new 3D spherical supramolecular polymers. The structure of the supramolecular polymers has been inferred on the basis of UV/Vis absorption, electron paramagnetic resonance, cyclic voltammetry, and dynamic light scattering (DLS) analysis, as well as by comparing these properties with those of the self-assembled structures of mono-, di-, and tritopic control compounds. DLS experiments revealed that the spherical supramolecular polymers had hydrodynamic diameters of 68 nm for T1 (75 μM) in acetonitrile and 105 nm for T2 (75 μM) in water/acetonitrile (1:1). The 3D spherical structures of the supramolecular polymers formed in different solvents were also supported by SEM and AFM experiments.

Metal-ion-promoted intermolecular electron transfer between anthraquinone-based tetrathiafulvalene derivative and p-chloranil

Based on copper (I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction, a novel anthraquinone-based tetrathiafulvalene (4) was synthesized through the reaction of the terminal alkyne compound (1), 1,8-dispropargyloxyanthraquinone and the terminal azide compound (3), 2-(2-azidoethylthio)-3,6,7-tris(methylthio)tetrathia-fulvalene in 52% yield. The compound 4 was characterized by 1H NMR, FT-IR, 13C NMR, MS and elemental analysis. The cyclic voltammogram of 4 shows as expected quasi-reversible redox behavior for anthraquinone and reversible redox for tetrathiafulvalene units. The fluorescence experiments have shown that compound 3 has a good selectivity with Al3+ and the complexation of 4 with Al3+ in a 1:1 complex mode gives an enhanced fluorescence change at 558nm. In CHCl3–CH3CN (v:v=1:1) solvent, the binding constant for the complex 4 and Al3+ is 3400dm3mol−1 at room temperature. Compound 4 may be used as a new fluorescent sensor for Al3+ ion. Meanwhile, the UV–vis spectra experiments show that many metal ions cannot oxidize the TTF units of 3 excluding Cu2+ and Hg2+ ions. Interestingly, the intermolecular electron transfer between 4 and p-chloranil (Q) did not apparently occur, however, the only two Al3+ and Pb2+ among tested metal ions may trigger the intermolecular electron transfer between 4 and Q, which may be ascribed to the synergic coordination of the radical anion of Q, nitrogen atoms of triazole and oxygen atoms of anthraquinone units in 4 with Al3+ or Pb2+ ions, whereas, the effects of Al3+ ion are obviously larger than that of Pb2+ ion.

Intra- and Intermolecular Charge Transfer in Aggregates of Tetrathiafulvalene-Triphenylmethyl Radical Derivatives in Solution

An extensive investigation of aggregation phenomena occurring in solution for a family of electron donor-acceptor derivatives, based on polychlorotriphenylmethyl radicals (PTM) linked via a vinylene-bridge to tetrathiafulvalene (TTF) units, is presented. A large set of temperature and/or concentration dependent optical absorption and electron spin resonance (ESR) spectra in a solution of dyads bearing different number of electrons and/or with a hydrogenated PTM residue offer reliable information on the formation of homo dimers and mixed valence dimers. The results shed light on the reciprocal influence of intramolecular electron transfer (IET) within a dyad and the intermolecular charge transfer (CT) occurring in a dimer between the TTF residues and are rationalized based on a theoretical model that describes both interactions.

Selective Redox-Active Molecular Receptors for K+ and Ag+

Two new tetrathiafulvalene based receptors in which the favorable redox properties of the tetrathiafulvalene unit are coupled to either a benzo-crown (X = O) or a dithiabenzo-crown (X = S) ether binding site were designed and synthesized as receptors for K(+) and Ag(+). The receptors display a good (K(+), X = O) to strong (Ag(+), X = S) affinity toward the cation and a high discrimination against other metal cations.

Biophysical and RNA Interference Inhibitory Properties of Oligonucleotides Carrying Tetrathiafulvalene Groups at Terminal Positions

Oligonucleotide conjugates carrying a single functionalized tetrathiafulvalene (TTF) unit linked through a threoninol molecule to the 3′ or 5′ ends were synthesized together with their complementary oligonucleotides carrying a TTF, pyrene, or pentafluorophenyl group. TTF‐oligonucleotide conjugates formed duplexes with higher thermal stability than the corresponding unmodified oligonucleotides and pyrene‐ and pentafluorophenyl‐modified oligonucleotides. TTF‐modified oligonucleotides are able to bind to citrate‐stabilized gold nanoparticles (AuNPs) and produce stable gold AuNPs functionalized with oligonucleotides. Finally, TTF‐oligoribonucleotides have been synthesized to produce siRNA duplexes carrying TTF units. The presence of the TTF molecule is compatible with the RNA interference mechanism for gene inhibition.

Chiroptical, linear, and second-order nonlinear optical properties of tetrathiafulvalenylallene: a multifunctional molecular material

Time-dependent density functional theory (TDDFT) calculations have been used to investigate chiroptical, linear, and second-order nonlinear optical (NLO) properties of the novel tetrathiafulvalenylallene in both neutral and two cationic states for the first time. The calculated UV-Vis/ECD spectra of the studied compound are in good agreement with the experimental ones, which can be used to assign its absolute configuration (AC) with high confidence. From neutral state to the two cationic states, the studied compound exhibits pronounced different chiroptical effects and second-order NLO response values. For example, the calculated β0 value of 12+ is 10.36 times as large as that of 1, while the β0 value of 14+ is 46.51 times as large as that of 1. These effects mainly result from the structural modifications of TTF units in the redox process. It is found that charge transfer between the tetrathiafulvalene (TTF) unit and the allene framework plays a key role in determining the chiroptical properties and electronic transition properties. It is interesting to find that the two benzene rings have vanishingly small effects on the chiroptical properties. The studied compound could act as both a chiroptical switch and NLO switch material from the standpoint of different chiroptical and NLO responses, reversible redox processes, and high stability. The effects of different functionals and basis sets, including solvent effects on the UV-Vis/ECD spectra were also considered.

Induced Self‐Assembly of a Tetrathiafulvalene‐Based Open‐Shell Dyad through Intramolecular Electron Transfer

An organic switch: An open-shell dyad, consisting of an electron acceptor perchlorotriphenylmethyl radical unit linked to an electron π-donor tetrathiafulvalene unit through a vinylene π-bridge, was synthesized (see picture). The self-assembly of the dyad in solution induced by its intramolecular electron transfer was studied.

Inclusion of Tetrachloroquinone and Metal Ions in a Macrotricyclic Molecule with a Tetrathiafulvalene Moiety Prompts Intermolecular Electron Transfer

And here′s your host: The synthesis and characterization of triptycene-based cylindrical macrotricyclic molecule 1, which contains one tetrathiafulvalene (TTF) unit and four glycol chains, is reported. Absorption and ESR spectroscopic studies show that intermolecular electron transfer occurs from the TTF unit in 1 to a tetrachloroquinone guest in the presence of metal ions. A triptycene-based cylindrical macrotricyclic molecule 1, which contains one tetrathiafulvalene (TTF) unit and four glycol chains, is reported. Both absorption and ESR spectroscopic studies clearly indicate that intermolecular electron transfer occurs from TTF in 1 to tetrachloroquinone in the presence of certain metal ions (e.g. Sc3+, Pb2+, and Zn2+). Based on comparative studies with 3 and 5, the close intermolecular alignment between 1 and tetrachloroquinone is proposed to occur by the synergic coordination of metal ions with oxygen atoms of the glycol chains and tetrachloroquinone (as well as the sulfur atoms of TTF). The intermolecular electron transfer is facilitated by the positive shift of the reduction potentials of tetrachloroquinone through coordination with metal ions, and the close alignment of 1 and tetrachloroquinone, which is beneficial for stabilizing the electron-transfer state. 1 Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

A Tetrathiafulvalene‐Functionalized Radiaannulene with Multiple Redox States

Multiple states: Fusing a central expanded radiaannulene (RA) core with two tetrathiafulvalene (TTF) units furnishes a molecule that can exist in several redox states with characteristic UV/Vis/IR absorptions. The radical cation was found to be of mixed valence (MV) character as reflected by a low-energy intervalence transition.

Inside Cover: A Tetrathiafulvalene-Functionalized Radiaannulene with Multiple Redox States (Angew. Chem. Int. Ed. 25/2012)

A fused Weitz/Wurster-type redox system has been prepared by fusing a central expanded radiaannulene core with two tetrathiafulvalene units. The system formally gains Hückel aromaticity by either oxidation (6π-dithiolium units) or reduction (14π-octadehydroannulene unit) and can exist in several redox states with characteristic UV/Vis/IR absorptions. More about this system can be found in the Communication by M. Brøndsted Nielsen and co-workers on page 6099 ff.

ChemInform Abstract: Preparation and Optical and Electrochemical Properties of Unsymmetrical Phthalocyanines with One or Two TTF Units.

AbstractUnsymmetrical phthalocyanines, e.g. (III), with one tetrathiafulvalene unit are prepared.

Twists and turns in the hierarchical self-assembly pathways of a non-amphiphilic chiral supramolecular material

The formation of helical self-assembled fibres by a C(3) symmetric molecule incorporating three tetrathiafulvalene units is shown to be influenced dramatically by the processing conditions, leading to a variety of different chiral forms, including unprecedented croissants.

A rigid donor–acceptor daisy chain dimer

A functionalised cyclobis(paraquat-p-phenylene) attached by a rigid linker to a tetrathiafulvalene unit, which is incapable of self-complexation, forms preferentially a [c2]daisy chain which undergoes rapid disassociation and reassociation on the (1)H NMR time-scale above room temperature.

Incorporation of fused tetrathiafulvalene units in a DPP–terthiophene copolymer for air stable solution processable organic field effect transistors

A new terthiophene–diketopyrrolopyrrole (DPP) copolymer has been synthesised in which the central thiophene ring within the terthiophene repeat unit is attached to a fused tetrathiafulvalene (TTF). The electrochemical and absorption data of the polymer, p(DPP-TTF), are presented, and the multi-redox states are investigated by UV-vis spectroelectrochemistry. Bottom gate/bottom contact field effect transistors were fabricated from films of p(DPP-TTF) annealed at 200 °C. The material, which under these conditions forms a fibrous structure, exhibited hole mobilities of 4 ± 2 × 10−2 cm2 V−1 s−1 with an on/off ratio of 1 × 104. The transistors showed little sign of degradation over 15 days of exposure under ambient conditions, demonstrating excellent air-stability. This characteristic is attributed to the incorporation of the TTF unit into the polymer.

Donor–Acceptor Ring‐in‐Ring Complexes

The self-assembly of three donor-acceptor ring-in-ring complexes, prepared from the π-electron-deficient tetracationic cyclophane, cyclobis(paraquat-4,4'-biphenylene), and three large π-electron-rich crown ethers (each 50-membered rings) containing dioxynaphthalene (DNP) and tetrathiafulvalene (TTF) units in pairs (DNP/DNP, DNP/TTF and TTF/TTF), is reported. (1)H NMR spectroscopic analyses are indicative of the formation of 1:1 complexes in CD(3)CN, whilst the charge-transfer interactions between the DNP and TTF units of the crown ethers and the tetracationic cyclophane have permitted the measurement of binding constants of up to 4×10(3) M(-1) in CH(3)CN to be made using UV/Vis spectroscopy. Ring-in-ring complexes are proposed as intermediates in the stepwise synthesis of molecular Borromean rings (BRs) comprised of three different rings. With the particular choice of crown ethers, the 1:1 complexes have polyether loops that protrude from the donor-acceptor recognition point above and below the mean plane of the tetracationic cyclophane, which, ideally, could conceivably bind dialkylammonium centers present in a third ring. X-ray crystallographic analyses of the solid-state superstructures of two of the three 1:1 complexes reveal, however, the presence of prodigious CH···O interactions between the polyether loops of the crown ethers and the rims of the cyclophane, no doubt stabilizing the complexes, but, at the same time, masking their potential recognition sites from further interactions that are essential to the subsequent emergence of the third ring. The solid-state superstructure of one of the crown ethers binding two dibenzylammonium ions provides some insight into the design requirements for the next generation of these systems; longer polyether loops may be required to allow optimal interactions between all components. It has become clear during a pursuit of the stepwise synthesis of the molecular BRs that, when designing complex mechanically interlocked molecules utilizing multiple recognition sites, the unsullied orthogonality of the recognition motifs is of the utmost importance.

Synthesis and properties of tetrathiafulvalene-porphyrin assemblies

Two donor-σ-acceptor molecular systems incorporating tetrathiafulvalene (TTF) and tetraphenylporphyrin (TPP) units, TTF-TPP (dyad 1) and TTF-TPP-TTF (triad 2), were synthesized. Both dyad 1 and triad 2 and their synthetic intermediates have been characterized by 1H nuclear magnetic resonance (1H NMR) and mass spectrography (MS). Their ultraviolet and visible spectroscopy (UV-Vis) and cyclic voltammetry (CV) showed negligible intramolecular charge transfer interaction in their ground states. Their fluorescence intensity was strongly quenched compared with TPP, which implied the photoinduced electron transfer occurred from the TTF unit to the TPP unit in the excited state. On the other hand, their fluorescence intensity could be modulated by sequential oxidation of the TTF unit using chemical methods, which exhibited their potential application in fluorescence molecular switch.