Redox-active proligands from the direct connection of 1,3-dithiol-2-one to tetrathiafulvalene (TTF): syntheses, characterizations and metal complexation

International audienceIn the search for novel tetrathiafulvalene-substituted dithiolene ligands, two tetrathiafulvalene (TTF) molecules directly connected to 1,3-dithiol-2-one fragments have been synthesized and characterized by single crystal X-ray diffraction, electrochemical and spectroscopic analyses. TTF1 was obtained, in moderate yield, by the cross-coupling of 4,5-bis(methylthio)-1,3-dithiole-2-one with 4,4′-bis(1,3-dithiole-2-one) in triethylphosphite, whereas for TTF2, the 1,3-dithiol-2-one fragment was introduced, in high yield, by an original reaction of the alkyne group of an ethynyl TTF (Me3TTF-C[triple bond, length as m-dash]CH) with xanthogen in the presence of a radical initiator. Opening of the 1,3-dithiol-2-one fragments with sodium methanolate leads to the formation of two new 1,2-dithiolate ligands functionalized with redox-active TTF moieties, which can efficiently coordinate metals. As an illustration, two original heteroleptic bis(cyclopentadienyl)dithiolene titanium complexes were isolated and characterized

Electroactive 1,5-benzodiazepines bearing either a tetrathiafulvalene or a ferrocene moiety

International audienceThe synthesis of a series of electroactive 1,5-benzodiazepines bearing either a ferrocene or tetrathiafulvalene core, acting as the electroactive moiety, is reported. The electron donating ability of these redox active 1,5-benzodiazepines is described together with their molecular structures, investigated by X-ray diffraction studies

C--I NC halogen bonding in two polymorphs of the mixed-valence 2:1 charge-transfer salt (EDTTTF- I2)2(TCNQF4), with segregated versus alternated stacks

International audienceOxidation of diiodoethylenedithiotetrathiafulvalene (EDT-TTF-I2), C8H4I2S6, with the strong oxidizer tetrafluorotetracyanoquinodimethane (TCNQF4), C12F4N4, affords, depending on the crystallization solvent, two polymorphs of the 2:1 charge-transfer salt (EDT-TTF-I2)2(TCNQF4), represented as D2A. In both salts, the TCNQF4 is reduced to the radical anion state, and is associated through short C-I...NC halogen bonds to two EDT-TTF-I2 molecules. The two polymorphs differ in the solid-state association of these trimeric D-A-D motifs. In polymorph (I) the trimeric motif is located on an inversion centre, and hence both EDT-TTF-I2 molecules have +0.5 charge. Together with segregation of the TTF and TCNQ derivatives into stacks, this leads to a charge-transfer salt with high conductivity. In polymorph (II) two crystallographically independent EDT-TTF-I2 molecules bear different charges, close to 0 and +1, as deduced from an established correlation between intramolecular bond lengths and charge. Overlap interactions between the halogen-bonded D0-A^{{-}{\bullet}}-D^{{+}{\bullet}} motifs give rise, in a perpendicular direction, to diamagnetic A22- and D0-D22+-D0 entities, where the radical species are paired into the bonding combination of respectively the acceptor LUMOs and donor HOMOs. The strikingly different solid-state organization of the halogen-bonded D-A-D motifs provides an illustrative example of two modes of face-to-face interaction between [pi]-type radicals, into either delocalized, uniform chains with partial charge transfer and conducting behaviour, or localized association of radicals into face-to-face A22- and D22+ dyads

Cis and trans-bis(tetrathiafulvalene-acetylide) platinum(II) complexes: syntheses, crystal structures, and influence of the ancillary ligands on their electronic properties.

International audienceA series of four platinum(II) complexes bearing two tetrathiafulvalene acetylide ligands coordinated either cis or trans to the metal center are reported: cis-Pt(bipy)(C≡CMe(3)TTF)(2), cis-Pt(tBu(2)bipy)(C≡CMe(3)TTF)(2), cis-Pt(dppe)(C≡CMe(3)TTF)(2) and trans-Pt(PPh(3))(2)(C≡CMe(3)TTF)(2). The X-ray diffraction studies of the four complexes are reported and discussed. The electrochemical investigations carried out by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) evidenced different redox behavior as a function of the ancillary ligand. Only for the cis-Pt(dppe)(C≡CMe(3)TTF)(2) complex is the first oxidation wave resolved (ΔE = 70 mV) into two one-electron processes. Spectroelectrochemical investigations performed on the four complexes did not evidence any electronic interactions between the two organic electrophores. The splitting of the first oxidation wave observed in cis-Pt(dppe)(C≡CMe(3)TTF)(2) is mainly explained by the non-equivalence of the two TTF moieties induced by the geometrical constraint imposed by the ancillary dppe ligand as found by density functional theory calculations

Chiral electron-rich bis(cyclopentadienyl) dithiolene molybdenum complexes

International audienceEnantiomerically pure electron rich Cp2Mo(dithiolene) complexes have been synthesized from the enantiopure dithiolene ligands, namely the (R)- and the (S)-3(1-phenylethyl)-1,3-thiazoline-2-thione-4,5-dithiolate ligands. These heteroleptic molybdenum complexes act as very good electron donors, as demonstrated through electrochemical investigations. Both isomers form charge transfer salts with TCNQ with a 1:1 stoechiometry which have been characterized by single crystal X-ray diffraction, EPR and UV–vis spectroscopic investigations. Circular dichroism (CD) experiments were also carried out on the neutral (R) and (S) enantiomers as well as on the mono oxidized species of these Cp2Mo dithiolene complexes

Mixed-valence gold bis (diselenolene) complex turning metallic under pressure.

While oxidation of d8 anionic gold bis(dithiolene) complexes most often affords the corresponding neutral radical single-component conductor, an original gold bis(diselenolene) complex isolated as a Ph4P+ salt affords upon electrocrystallization a mixed-valence 1 : 2 salt, [Ph4P][Au(Me-thiazds)2]2 (Me-thiazds: 2-methyl-1,3-thiazoline-2-thione-4,5-diselenolate). This salt exhibits a rare charge alternation associated with the simultaneous presence of both cis and trans isomers of the gold complex in the conducting layers. The salt is semiconducting (σRT = 3 × 10−2 S cm−1, Eact = 0.137 eV) but, in contrast with other 1 : 2 gold bis(dithiolene) salts, turns metallic under pressure (>10 GPa). [Ph4P][Au(Me-thiazds)2]2 is thus the first metallic, fully characterized, 1 : 2 mixed-valence gold complex, opening the door for the preparation of highly conducting solids of this type

New Trends in Beverage Packaging Systems: A Review

New trends in beverage packaging are focusing on the structure modification of packaging materials and the development of new active and/or intelligent systems, which can interact with the product or its environment, improving the conservation of beverages, such as wine, juice or beer, customer acceptability, and food security. In this paper, the main nutritional and organoleptic degradation processes of beverages, such as oxidative degradation or changes in the aromatic profiles, which influence their color and volatile composition are summarized. Finally, the description of the current situation of beverage packaging materials and new possible, emerging strategies to overcome some of the pending issues are discussed

Synthèses et étude de la coordination à des métaux de nouveaux ligand électroactifs (les tétrathiafulvalènythioalkylphosphines mono ou polydentates)

L objectif de ce travail est l étude de nouveaux tétrathiafulvalène-thioalkylphosphines et leur utilisation en tant que ligands électroactifs pour l élaboration de molécules hybride organique-inorganiques. Nous décrivons les synthèses de TTF mono, di et tétrasubstitués possédant des espaceurs alkylthio entre le cœur TTF et la fonction phosphine, ainsi que leur coordination à des complexes métalliques. Nous avons mis en évidence la versatilité du ligand TTF thioalkylmonophosphine qui peut agir comme un ligand mono (P) ou bidentate (P,S). Des TTF cyclophanes comportant un métal par cycle ont également été préparés à partir des TTF diphosphines. Des essais de formation de complexes par transfert de charge à partir de ces mêmes TTF cyclophanes sont décris. Nous présentons également la synthèse de TTF biscyclophanes dont il a été possible de contrôler la formation de chaque cycle soit latérale au cœur TTF soit à chaque extrémité des dithioles.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF