TTF-based Donor Research Articles

Synthesis and structures of polyiodide radical cation salts of donors combining tetrathiafulvalene with multiple thiophene or oligo-thiophene substituents

The preparation and structures of the radical cation salts of a series of new TTF-based donors bearing thiophene or oligothiophene side chains with polyiodide counterions are described.

Enantiopure and racemic radical-cation salts of bis(2'-hydroxylpropylthio)(ethylenedithio)TTF with polyiodide anions.

The chiral TTF-based donor molecule bis(2'-hydroxylpropylthio)(ethylenedithio)tetrathiafulvalene (BHPT-EDT-TTF) has produced enantiopure R,R and S,S radical-cation salts with polyiodide anions I3- and I82-. Enantiomorphic 6 : 6 donor : I3 phases grown from either the R,R or S,S donor are semiconducting with similar activation energies of 0.24-0.30 eV and 0.22-0.23 eV, respectively, and contain three unique face-to-face donor pairs whose relative orientation is determined by side chain conformations and hydrogen bonding. Racemic material under the same conditions gave an insulating centrosymmetric phase with R,R and S,S donor cations in a face-to-face pair partnered with an octaiodide dianion, and with a ca. 3 : 1 disorder between the enantiomers. Enantiopure BHPT-EDT-TTF yielded two further insulating crystalline phases of composition 2 : 2 with triiodide and 2 : 1 with octaiodide.

Stereoisomeric semiconducting radical cation salts of chiral bis(2-hydroxypropylthio)ethylenedithioTTF with tetrafluoroborate anions

A new chiral TTF-based donor has produced enantiopure R,R and S,S radical cation salts with the tetrafluoroborate anion as well as the nearly isostructural meso/racemate mixture.

Extended TTF-type donors fused with pyrazine units; synthesis and characterization

Pyrazinedicyanoethylthiotetrathiafulvalene, (pzdc-TTF) (1a), an extended TTF fused with a pyrazine moiety and also a dithiolene ligand precursor, was synthesized through a cross-coupling with triethyl phosphite between pyrazine-1,3-dithiole-2-thione (I) and 4,5-bis(2-cyanoethylthio)-1,3-dithiole-2-one (III). This reaction also yields to dipyrazine TTF derivative (1b) and 2,3,6,7-Tetrakis(2-cyanoethylthio)TTF (1c), resulting from the self-coupling reactions of the thione (I) and ketone (III). The crystal structure of 1a is composed by pairs of head to head donor stacks of pzdc-TTF molecules along b in opposite orientations. Single crystals of 1b revealed a new polymorph with a face-to-face π-stacking motif. The electrochemical properties of 1a studied by cyclic voltammetry (CV) in DMF, shows two single electron oxidation processes typical of TTF-based donors; one pair of asymmetric redox waves centered at 627mV versus Ag/Ag+ is ascribed to the couple [pzdc-TTF]+/[pzdc-TTF]2+, and one pair of quasi-reversible redox waves centered at 430mV is ascribed to the couple [pzdc-TTF]0/[pzdc-TTF]+.

Synthesis and characterization of the novel extended TTF-type donors with thiophenic units

Two new TTF-based donors that are dithiolene ligand precursors, 3-{5-[(2-cyanoethyl)thio]-2-(5,6-dihydrothieno[2,3- d][1,3]dithiol-2-ylidene-1,3-dithiol-4-yl)thio}propanenitrile, dtdt ( 1) and 3-({5-[(2-cyanoethyl)thio]-2-thieno[2,3- d][1,3]dithiol-2-ylidene-1,3-dithiol-4-yl)thio}propanenitrile, α-tdt ( 2), were synthesized and characterized. The electrochemical properties of these compounds were studied by cyclic voltammetry (CV) in acetonitrile. Compound 1 shows two reversible oxidation process at 1 E 1/2 = 0.639 V and 2 E 1/2 = 0.997 V versus Ag/AgCl. This same processes occurs at 1 E 1/2 = 0.612 V and 2 E 1/2 = 0.906 V in the case of 2. The crystal structures confirm the ability of these molecules to establish interactions with their neighbours through the peripheral sulfur atoms.

A field-effect transistor consists of spin-polarized TTF-based donor

TTF-based organic donor molecule bearing stable organic radical moiety and long alkyl chains was synthesized and fabricated into a FET device structure. A fused solid film of the donor radical on a surface-oxidized silicon wafer with an interdigited electrode of 2 μm gap as source and drain electrodes indicated FET characteristics although the observed hole mobility was very low. This is the first observation of a FET characteristic of an organic radical molecule.

Hydrogen-bonded charge-transfer complexes of TTFs containing nucleobase or imidazole moiety

Novel electron-donor molecules based on tetrathiafulvalene (TTF) and imidazole skeleton with hydrogen-bonded (H-bonded) functionality 1-5 and 7-10 have been designed and synthesized. The cyclic voltammograms for TTF-based donors 1-5 exhibit two-stage one-electron reversible waves, while oligo(imidazole)s 7-10 show irreversible one. The room-temperature conductivities of their tetracyanoquinodimethane (TCNQ) complexes for 1, 2, 4, 5, 8 and 9 exhibit 0.11, 0.07, 2.3, 0.38, 0.16 and 0.10 Scm -1 , respectively, revealing high electrical conductivity than those of known charge-transfer (CT) complexes derived from organic donors with amino or hydroxyl groups and organic acceptor molecules.

A novel TTF-based donor carrying four nitronyl nitroxides

A novel TTF-based tetraradical donor was synthesized and its electronic structure was fully characterized by spectroscopic measurements, magnetic susceptibility measurements, and electrochemical analyses.

Charge Transfer Assisted Ferromagnetic Coupling Observed in an Ion-Radical Salt of a Cross-Cyclophane TTF-Based Donor

Abstract The ferromagnetic interaction was observed in a conducting ion-radical salt of a TTF-based cross-cyclophane type dimeric donor.

Hydrogen-bonded charge-transfer complexes of TTF containing a uracil moiety: crystal structures and electronic properties of the hydrogen cyananilate and TCNQ complexes.

[structure: see text] A novel TTF-based donor with a uracil moiety, TTF-(1-n-butyluracil-5-yl) (TnbU), was synthesized. Crystal structures of both TnbU and the charge-transfer complex of TnbU-hydrogen cyananilate possess complementary double hydrogen bonds through uracil moieties and pi-stacking dimer structures between TTF skeletons. Furthermore, the TnbU-TCNQ charge-transfer complex shows a high electrical conductivity underlying the partial charge-transfer accompanied by a hydrogen-bonding interaction, which was substantiated in terms of the measurements of the IR, electronic spectra, and conductivity.

One-dimensional double chain composed of carbamoylmethylthio-substituted TTF-based donor in ion radical salt

Carbamoylmethylthio-substituted TTF-based donors afforded inclusion-type salts with a BF4 counter ion or an F4-TCNQ acceptor. The crystal structures of these salts are characterized by a one-dimensional double chain composed of singly-oxidized donors via SOMO–SOMO interaction and side-by-side S⋯S contacts. Counter ions of BF4 are hydrogen-bonded to the amide groups. On the other hand, F4-TCNQ acceptors are stacked in a channel created by a stair-like arrangement of donor chains. The thermally activating magnetic susceptibility of the F4-TCNQ complex was interpreted in terms of a double-chain frustrated spin system.

Novel spin-polarized TTF donors affording ground state triplet cation diradicals

The concept of “spin-polarized” donor was successfully extended to TTF-based donor radicals. A series of TTF derivatives carrying a phenyl nitronyl nitroxide group were prepared, and they turned out to afford ground state triplet cation diradicals through one-electron oxidation. Such “spin-polarized” TTF donors are expected to become building blocks for organic conducting ferromagnets.

BEDT-TTF and related donor molecules — made easy

Two new general approaches to TTF-based donor molecules have been developed. Route A gave, after basic cleavage of thiapendione ( 1) and direct alkylation of intermediate ( 2), the corresponding 4,5-disubstituted 1,3-dithiol-2-ones of general formula 4 as exemplified in Schemes 1 and 2. The more versatile route B involves isolation of the unstable intermediate 2 as chelate complex 3, which then gives upon treatment with alkyl/acyl halides compounds of type 4. Compounds ( 4) can either be coupled/cross-coupled in triethyl phosphite in known manner to give symmetric/asymmetric donors molecules or be used as precursors for the preparation of other sulfur containing heterocycles or metal complexes. Versatility, yields and high purity of intermediates and final products offer an interesting alternative to literature procedures

Syntheses, structures and electrical properties of cation radical salts based on TTF derivatives containing O, S and Se

Some chemical modifications of TTF-based donor molecules are described. (TMET-STF) 2Au(CN) 2 is isostructural with the Bechgaard salt and has a quasi one-dimensional electronic structure. We have investigated the pressure effect on the electric resistivity. The metal-insulator transition at 18 K is easily suppressed under pressure (> ca. 2.9 kbar). At ambient pressure, the low-temperature X-ray crystal analyses down to 10 K indicate an enhancement of one-dimensional character. GaCl 4 and FeCl 4 salts of TOST are metallic down to 4.2 K and have the κ-type structure. The AuBr 2 salt of SO is metallic down to 1.5 K and isostructural with β″-(BEDT-TTF) 2AuBr 2.