Amphiphilic Tetrathiafulvalene Research Articles

Supramolecular conducting microfibers from amphiphilic tetrathiafulvalene-based organogelator

An amphiphilic tetrathiafulvalene molecule was designed and readily synthesized. The am-TTF can gelate a variety of organic solvents in view of multiple intermolecular interactions, especially in polar solvent. SEM observation provided clear evidence for the self-assembled micro/nanofibers morphologies in gelation state. Moreover, XRD measurements indicated the formation of highly-ordered columnar structures. The FT-IR spectra revealed that the formation of mixed-valence states with the absorption over 1700 cm−1, showing the semiconductive behaviors with the conductivity of 10−4 S/cm. The am-TTF based conducting fibers could be promising candidates for organic electronics.

Macroscopically oriented hierarchical structure of the amphiphilic tetrathiafulvalene molecule

Since the physical properties of electronic and biological molecules strongly depend on the nature of molecular self-assembly and organization, it is essential to control their molecular packing structure and morphology on the different length scales. In this aspect, a programmed amphiphilic tetrathiafulvalene (TTF) molecule (abbreviated as amph-7TTF14) was newly designed and synthesized. Differential scanning calorimetry (DSC) combined with one-dimensional (1D) wide angle X-ray diffraction (WAXD) techniques revealed that a highly ordered crystalline phase emerged below the isotropic phase. From the 2D WAXD pattern of the macroscopically oriented amph-7TTF14 film, the crystal structure was identified to be a monoclinic unit cell. The face-to-face π–π interaction between TTF groups and the nanophase separation between rigid TTF groups and flexible hydrophobic alkyl and hydrophilic tri(ethylene oxide) tails were the main driving forces for the self-assembly of amph-7TTF14. The morphological observations using transmission electron microscopy (TEM), atomic force microscopy (AFM), and polarized optical microscopy (POM) indicated that the amph-7TTF14 formed not only flat ribbons but also scrolls and helixes, in which the ribbons further aggregated to create the fibrous hierarchical structures. Based on the experimental results and careful analyses, it was realized that the scrolls and helices were induced by the unbalanced surface stresses generated during the crystallization process. When the macroscopically oriented fibrous hierarchical structure is properly applied to the electrooptical and bio-mimetic devices, the targeted physical properties may be significantly improved and tuned for the specific practical applications.

Host–Guest Modulation of the Micellization of a Tetrathiafulvalene-Functionalized Poly(N-isopropylacrylamide)

The aqueous solution properties of amphiphilic tetrathiafulvalene (TTF) end-functionalized poly(N-isopropylacrylamide) (PNIPAM) derivative 1 have been studied. Fluorescence spectroscopy, dynamic light scattering (DLS) and differential scanning calorimetry (Nano-DSC) were used to monitor the temperature-induced micellization and showed that 1 underwent two successive phase transitions corresponding to unimer-to-micelle and lower critical solution temperature (LCST) transitions, respectively. We have investigated the complexation properties of the TTF unit toward cyclobis(paraquat-p-phenylene) (CBPQT4+) or the randomly methylated β-cyclodextrin (RAMEB) to manipulate the amphiphilicity of 1 and to control the unimer-to-micelle phase transition by forming pseudorotaxane-like architectures. For the RAMEB complex with 1, the addition of a competitive guest such as 1-adamantanol resulted in the restoration of amphiphilicity of polymer 1 and consequently the reformation of micelles.

Self-assembly and nanostructure formation of amphiphilic 4,5-bis(2-pyridylethynyl)tetrathiafulvalenes

Amphiphilic tetrathiafulvalene (TTF) having both long alkylthio chains and pyridylethynyl groups was synthesised, and its nanostructure and redox properties were investigated. The bis(pyridylethynyl)TTF formed 1D flat and helical tapes. Since these tapes were of micrometre size, the conductivities of neutral and I2-doped tapes could be measured by directly attaching gold wires to the tape. After doping with I2, the colour of the tape changed from purple to black, and the tape behaved as a semiconductor up to 2.6 × 10− 4 S cm− 1.

Anisotropy in structural and physical properties in tetrathiafulvalene derivatives-based zone-cast layers as seen by Raman spectroscopy, UV-visible spectroscopy, and field effect measurements

We have studied anisotropy of thin layers of amphiphilic tetrathiafulvalene derivatives (TTF-4SCn, with n=12, 18, and 22) obtained by zone-casting technique. All the films show optical anisotropy, as seen by polarized optical microscopy and polarized UV-visible spectroscopy. By using polarized Raman spectroscopy an angular dependence of intensity of different vibrational modes in respect to the zone-casting direction was determined. It was found that intensities of the modes related to central and ring C=C vibrations in the TTF core depend very strongly on the angle between the zone-cast direction and polarization plane of incident laser light. Comparison of the deduced orientation of the molecules in one of the films (TTF-4SC18) with its crystal structure shows that the polarized Raman spectroscopy can be useful for controlling orientation of molecules in thin films (e.g., for online monitoring). Organic field effect transistors (OFETs), with channels oriented in parallel and perpendicularly to the zone-casting direction, were built using the oriented TTF-4SCn films. In all cases a strong anisotropy of the charge carrier mobility (μ) was found; the best results were obtained for OFETs with TTF-4SC18, for which μ∥=0.25 cm2/V s, ON/OFF>105, and μ∥/μ⊥≈170.

Langmuir-Blodgett films of One-dimensional Nanowires composed of Amphiphilic Tetrathiafulvalenes and Electron Acceptor

ABSTRACTWe found that novel amphiphilic tetrathiafulvalene (TTF; 1) organized into supramolecular assemblies by the addition of electron acceptor 2,3,5,6-tetrafluoro-7,7'f,8,8'f-tetracyano-p-quinodimethane (F4TCNQ) at the air-water interface. The assemblies on the air-water interface can be transferred onto the surface of mica and the morphologies of transferred films were investigated by AFM. The morphology of Langmuir-Blodgett films strongly depended on the ratio between 1 and F4TCNQ. Film of 1:1 mixture of 1 and F4TCNQ formed nanoscopic wires having an average dimension of 5.0 (height) × 70 (width) × 3000 (length) nm. On the other hand, the film of 2:1 mixture of 1 and F4TCNQ showed the mixed domains of wires and flat monolayers. Thus, the completely charge-transferred complex (1+)(F4TCNQ-) formed one-dimensional nanowires having a micrometer length. Room temperature electrical conductivities of cast film for 1:1 and 2:1 mixed layers of 1 and F4TCNQ were 2.4 × 10−4 and 8.0 × 10−5 S cm−1, respectively.

Synthesis of optically active amphiphilic tetrathiafulvalene derivatives

The synthesis and characterization of novel chiral tetrathiafulvalenes bearing two long alkyl chains at one end of the π-electron rich unit and different functional groups—ester, acid or thiolate—at the other extreme is described. The synthetic method requires the preparation of 1,3-dithiol derivatives with two stereogenic centers. Different routes and reaction conditions were explored to form these compounds, whose optimized synthesis involved the nucleophilic substitution of a chiral bromo methylene derivative with tetrabutylammonium bis(2-thioxo-1,3-dithiole-4,5-dithiolate)zincate. The tetrathiafulvalenes were prepared by coupling the 1,3-dithiol derivative with 4,5-bis(methoxycarbonyl)-1,3-dithiol-2-one or 4,5-bis(2-cyanotehylthio)-1,3-dithiol-2-thione. The products were fully characterized, including by circular dichroism spectroscopy, which confirmed their optical activity. They are promising candidates to be used as building blocks in supramolecular materials for molecular electronics, to produce systems with unique electrical, magnetic or optical properties that stem from their chirality.

Amphiphilic Tetrathiafulvalene Derivative: Charge-Transfer Complexation Behavior in Solutions

Abstract An amphiphilic tetrathiafulvalene (1) was prepared by condensation of tetrathiafulvalene-4-carboxylic acid with reduced Triton X-100 to avoid crystallization. Its charge-transfer (CT) complexation behaviors were examined with a strong electron acceptor, i.e., 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), in solutions. Although tetrathiafulvalene, (4-tetrathiafulvalenyl)methyl acetate (2), and methyl tetrathiafulvalene-4-carboxylate (4) reacted with DDQ to produce a dark red precipitates in CHCl3 and (4-tetrathiafulvalenyl)methyl stearate (3) with DDQ formed black red colloidal dispersions in CHCl3, an equimolar amount of DDQ with 1 in CHCl3 formed a dark red solution without any precipitates. The UV spectrum of the solution of 1 and DDQ in CHCl3 shows a broad peak in near-IR regions. The absorption maximum at 1300 nm (ε = 3.8 × 102 M−1 cm−1) that is tailing to beyond 2000 nm is derived from π-stacked arrangement of the TTF moiety and DDQ. UV–vis absorption spectra of 1 with DDQ in several organic solvents, i.e., acetonitrile, acetone, CH2Cl2, toluene, and CCl4, show that the CT complexation behavior of 1 was highly dependent on the solvent polarity.

A Magnetic Manganese Phosphonate Langmuir-Blodgett Film Containing a Tetrathiafulvalene Amphiphile

An amphiphilic tetrathiafulvalene derivative, with two alkylphosphonic acid substituents, has been prepared and used to form a mixed organic/inorganic Langmuir-Blodgett (LB) film containing a TTF-based organic network and a manganese phosphonate continuous lattice inorganic network. The inorganic network is isostructural with known manganese phosphonate layered solids, and undergoes magnetic ordering to a canted antiferromagnetic ground state. A model TTF derivative containing the alkylphosphonic acids, but without hydrophobic alkyl tails, was also synthesized and a manganese phosphonate solid, isostructural with the LB film, was prepared and characterized.

Electroabsorption of Amphiphilic Tetrathiafulvalene Derivatives / 7,7,8,8-Tetracyano-2,3,5,6-tetrafluoroquinodimethane Systems in Langmuir-Blodgett Films

Abstract External electric field effects on the electronic structures of charge transfer salts were examined for the first time in Langmuir-Blodgett films. Significant electroabsorption signals arising primarily from the first Stark effect were obtained for the films of amphiphilic tetrathiafulvalene derivatives / 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane 1 : 1 salts.

Conducting langmuir-blodgett films of new amphiphilic tetrathiafulvalene derivatives

New mono-functionalised, amphiphilic tetrathiafulvalene (TTF) derivatives have been synthesised and shown to form Langmuir-Blodgettt films, some of which are semiconducting ( δ rt = 10 −5-10 −2Scm −1 after iodine doping. These layers have been characterised by UV-Visible and IR spectroscopy in the undoped and doped states. X-ray crystal structures of related TTF derivatives substituted with a thioester and a thioamide group are presented.

New Amphiphilic Tetrathiafulvalene (TTF) Derivatives: Synthesis and Langmuir-Blodgett Filn Formation

New Amphiphilic Tetrathiafulvalene (TTF) Derivatives: Synthesis and Langmuir-Blodgett Filn Formation

New Amphiphilic Tetrathiafulvalene (TTF) Derivatives: Synthesis and Langmuir-Blodgett Film Formation

Abstract The synthesis of amphiphilic, cis-substituted TTF derivatives is described. Subsequent acid-catalysed trans-cis isomerization yields the amphiphilic species suitable for LB film formation. Langmuir multilayers transferred at a pressure of 25 nM m−1 with area per molecule of 52 Å2 have been deposited on various substrates, and the films characterized by UV-visible and X-ray diffraction experiments. Halogen-vapor doping of the deposited films has been achieved. The results of conductivity measurements on the films before and after doping are presented.