Switch over: All the disulfide moieties in the cations of an iodoplumbate display the same chiral conformation in a single crystal; however, during a phase transition (75 °C) half of these molecules ...undergo a conformational change, from the left‐ to the right‐handed helical form, and a true racemate is formed. This transition is reversible, and thus this compound can act as a second harmonic generation switch.
Electro-oxidation of tetramethyltetrathiafulvalene (TMTTF) in the presence of the chiral anion (1
S
)-camphor-10-sulfonate (S-camphSO
3
−
) in tetrahydrofuran/water medium afforded a 1/1 salt ...formulated as TMTTF·S-camphSO
3
·2H
2
O or 2-(4,5-dimethyl-1,3-dithiol-2-ylidene)-4,5-dimethyl-1,3-dithiole radical ion (1+) (1
S
)-7,7-dimethyl-2-oxobicyclo2.2.1heptan-1-ylmethanesulfonate dihydrate, C
10
H
12
S
4
+
·C
10
H
15
O
4
S
−
·2H
2
O. In this salt, two independent TMTTF units are present but, in both cases, the observed bond lengths and especially the central C=C distance 1.392 (6) and 1.378 (6) Å are in agreement with a complete oxidation of TMTTF which is thus present as TMTTF
.
+
radical cations. These cations form one-dimensional stacks in which they are associated two by two, forming dimers with short 3.472 (1) to 3.554 (2) Å S...S contacts. The two S-camphSO
3
anions present also form stacks and are connected with each other
via
the water molecules with many O—H...O hydrogen bonds ranging from 1.86 (3) to 2.15 (4) Å; the O—H...O hydrogen-bonding network can be described as being constituted of
C
2
2
(6) chains bearing
R
3
3
(11) lateral rings. On the other hand, the columns of cations and anions are connected through C—H...O hydrogen bonds, forming a system expanding in three directions; finally, the result is a three-dimensional network of O—H...O and C—H...O hydrogen bonds.
Electro-oxidation of tetra-methyl-tetra-thia-fulvalene (TMTTF) in the presence of the chiral anion (1S)-camphor-10-sulfonate (S-camphSO3 (-)) in tetra-hydro-furan/water medium afforded a 1/1 salt ...formulated as TMTTF·S-camphSO3·2H2O or 2-(4,5-dimethyl-1,3-di-thiol-2-yl-idene)-4,5-dimethyl-1,3-di-thiole radical ion (1+) (1S)-7,7-dimethyl-2-oxobi-cyclo-2.2.1heptan-1-ylmethane-sulfonate dihydrate, C10H12S4 (+)·C10H15O4S(-)·2H2O. In this salt, two independent TMTTF units are present but, in both cases, the observed bond lengths and especially the central C=C distance 1.392 (6) and 1.378 (6) Å are in agreement with a complete oxidation of TMTTF which is thus present as TMTTF (.) (+) radical cations. These cations form one-dimensional stacks in which they are associated two by two, forming dimers with short 3.472 (1) to 3.554 (2) Å S⋯S contacts. The two S-camphSO3 anions present also form stacks and are connected with each other via the water mol-ecules with many O-H⋯O hydrogen bonds ranging from 1.86 (3) to 2.15 (4) Å; the O-H⋯O hydrogen-bonding network can be described as being constituted of C 2 (2)(6) chains bearing R 3 (3)(11) lateral rings. On the other hand, the columns of cations and anions are connected through C-H⋯O hydrogen bonds, forming a system expanding in three directions; finally, the result is a three-dimensional network of O-H⋯O and C-H⋯O hydrogen bonds.
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‐TTF2O3S‐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.
Noncentrosymmetric electroconducting salts such as BEDT‐TTF2O3S‐C6H4‐CO2H BEDT‐TTF = bis(ethylenedithio)tetrathiafulvalene can be obtained by electro‐oxidation of tetrathiafulvalene derivatives in the presence of the dissymmetrical hydrogen‐bonding para‐carboxybenzenesulfonate anion.
The formation process of metallic Langmuir film on the water surface fabricated from BEDO-TTF (BO) and stearic acid (SA) is described. The in-situ observation by Brewster angle microscope revealed a ...creation of small islands after spreading the mixing solution on the water surface and then a formation of homogeneous Langmuir film by a coalescence of the islands with decreasing of the surface area. An appearance of mixed valence state of BO in both islands and Langmuir film was confirmed by polarization-modulated IR reflection absorption spectroscopy. A theoretical simulation of the spectra supports the bilayer model on the water surface, in which a metallic BO layer underlies between the SA layer and the water surface. An investigation on the Langmuir−Blodgett (LB) films transferred onto substrates by infrared spectroscopy implies the existence of hydrogen-bonded carboxylate groups of (R−COO···H···OOC−R)- in the SA layer. Finally, the optical conductivity in the LB films can be compared with those of the superconductor crystal (BO)2ReO4(H2O) through the Drude optical parameters obtained from the IR spectra fitting.
Umschalten: Alle Disulfideinheiten in den Kationen eines Iodoplumbatsalzes haben im Einkristall dieselbe chirale Konformation; doch bei einem Phasenübergang (75 °C) ändert die Hälfte der Moleküle ...ihre Konformation von der links‐ zur rechtsgängigen Helixform, und es entsteht ein echtes Racemat. Der Übergang ist reversibel, und die Verbindung kann als Frequenzverdopplungsschalter eingesetzt werden.
The title compounds are synthesized, using the oxidative coupling of TTF thiolates. The disulfide linkage induces approximate orthogonality between the two TTF units, while maintaining virtually ...unchanged their electrochemical properties.
The title compounds are synthesized, using the oxidative coupling of TTF thiolates. The disulfide linkage induces approximate orthogonality between the two TTF units, while maintaining virtually unchanged their electrochemical properties.
We have investigated the structural defects in poly (vinylene disulfide), -(S-CH=CH-S)
n
-, using optical, magnetic and surface spectroscopic techniques. This has been done by comparing the analysis ...results obtained on pristine samples with those on protic-acid-doped samples. In the undoped sample, the main type of defect is found on carbon broken bonds which gives rise to carbon-oxygen bonding due to oxidation of the sample. In doped samples, the sulfur sites are greatly affected by doping and appear as the main protonation sites. A careful analysis of all the results has enabled the role of the defects in the electrical conduction mechanism to be clarified.
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