Chiral Metallic DM-EDT-TTF Radical Cation Salts: Anion Size-Dependent Structural and Electronic Transitions, Charge Ordering, and Chirality-Induced Spin Selectivity.

Both enantiomers () and () of the chiral mixed-valence radical cation salts (DM-EDT-TTF)XO (X = Cl or Re) have been prepared by electrocrystallization. Single-crystal high-quality synchrotron radiation data allowed for the very accurate determination of their 298 and 18 K structures. At room temperature, they crystallize in the enantiomorphic space groups 22 and 22 for the () and () enantiomers, respectively, while at 18 K, the structures have been solved in the and space groups, respectively.

A highly conducting tetrathiafulvalene-tetracarboxylate based dysprosium(iii) 2D metal-organic framework with single molecule magnet behaviour.

The synthesis and whole characterization by a multitechnique approach of an unprecedented dysprosium(iii) 2D metal organic framework (MOF), involving the redox-active tetrathiafulvalene (TTF)-based linker TTF-tetracarboxylate (TTF-TC), are herein reported. The single-crystal X-ray structure, formulated as [Dy(TTF-TC)(HO)]·21HO (1), reveals a complex 2D topology, with hexanuclear Dy clusters as secondary building units (SBUs) interconnected by five linkers, stacked almost parallel in each layer and eclipsed along the [111] direction, leading to the formation of 1D channels filled by water molecules. The mixed valence of the TTF units is confirmed by both bond distance analysis, Raman microscopy and diffuse reflectance spectroscopy, and further supported by band structure calculations, which also predict activated conductivity for this material.

Chiral Spiro-Tetrathiafulvalenes: Synthesis, Chiroptical Properties, Conformational Issues and Charge Transfer Complexes.

Within this work we have investigated spiro-based tetrathiafulvalenes (TTFs) obtained as mixtures of stereoisomers from racemic spiro[5.5]undeca-1,8-dien-3-one. Compared to previously described spiro-TTFs, enantiomeric and diastereoisomeric forms have been here separated by chiral HPLC and fully characterized both experimentally and theoretically.

A redox active rod coordination polymer from tetrakis(4-carboxylic acid biphenyl)tetrathiafulvalene.

An enlarged version of the ubiquitous tetrathiafulvalene-tetrabenzoic acid is described, with 4,4'-biphenyl moieties as spacers between the coordination moieties and the electroactive core. The obtained rectangular ligand has a 14 × 22 Å size and is combined with Zn(II) under solvothermal conditions to yield a coordination polymer endowed with large cavities of . 15 × 11 Å/10 × 10 Å.

Bis(Vinylenedithio)-Tetrathiafulvalene-Based Coordination Networks.

Novel coordination polymers embedding electroactive moieties present a high interest in the development of porous conducting materials. While tetrathiafulvalene (TTF) based metal-organic frameworks were reported to yield through-space conducting frameworks, the use of S-enriched scaffolds remains elusive in this field. Herein is reported the employment of bis(vinylenedithio)-tetrathiafulvalene (BVDT-TTF) functionalized with pyridine coordinating moieties in coordination polymers.

Chiral Bis(tetrathiafulvalene)-1,2-cyclohexane-diamides.

Chiral bis(TTF) diamides have been obtained in good yields (54-74%) from 1,2-cyclohexane-diamine and the corresponding TTF acyl chlorides. The (,)- and (,)- enantiomers have been characterized by circular dichroism and the racemic form by single-crystal X-ray diffraction. The neutral racemic bis(TTF)-diamide shows the formation of a pincer-like framework in the solid state, thanks to the intramolecular SS interactions.

Charge-Ordering and Structural Transition in the New Organic Conductor δ'-(BEDT-TTF)CFCFSO.

We report structural, transport, and optical properties and electronic structure calculations of the δ'-(BEDT-TTF)CFCFSO (BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene) organic conductor that has been synthesized by electrocrystallization. Electronic structure calculations demonstrate the quasi-one-dimensional Fermi surfaces of the compound, while the optical spectra are characteristic for a dimer-Mott insulator. The single-crystal X-ray diffraction measurements reveal the structural phase transition at 200 K from the ambient-temperature monoclinic 2/ phase to the low-temperature orthorhombic 2 phase, while the resistivity measurements clearly show the first order semiconductor-semiconductor transition at the same temperature.

Conservation of structural arrangements and 3 : 1 stoichiometry in a series of crystalline conductors of TMTTF, TMTSF, BEDT-TTF, and chiral DM-EDT-TTF with the oxo-bis[pentafluorotantalate(v)] dianion.

The occurrence of isostructural conducting radical cation salts of diversely substituted tetrathiafulvalene (TTF) precursors with the same anion is most often limited to very similar derivatives such as tetramethyl-tetrathiafulvalene (TMTTF) and tetramethyl-tetraselenafulvalene (TMTSF). Here we show that the use of the oxo-bis[pentafluorotantalate(v)] dianion [TaFO] affords upon electrocrystallization of TMTTF, TMTSF, bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF), racemic dimethyl-ethylenedithio-tetrathiafulvalene (()-DM-EDT-TTF), and enantiopure (,)-DM-EDT-TTF a series of mixed valence crystalline radical cation salts with the same 3 : 1 stoichiometry. The donor layers show similar features in the five materials, such as alternation of trimeric units within stacks which arrange in parallel columns of β-type.

In Search of Chiral Molecular Superconductors: κ-[(S,S)-DM-BEDT-TTF] ClO Revisited.

The relationship between chirality and superconductivity is an intriguing question. The two enantiomeric crystalline radical cation salts κ-[(S,S)-DM-BEDT-TTF] ClO and κ-[(R,R)-DM-BEDT-TTF] ClO , showing κ-type arrangement of the organic layers, are investigated in search for superconducting chiral molecular materials following a 1992 report indicating the occurrence of a superconducting transition in the former compound. While the initial interpretation is presently challenged through in-depth temperature and pressure dependent single crystal resistivity measurements combined with band structure calculations, the two chiral conductors show metal like behavior with room temperature conductivities of 10-30 S cm at ambient pressure and stabilization of the metallic state down to the lowest temperatures under moderate pressures.

Magnetic Molecular Conductors Based on Bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) and the Tris(chlorocyananilato)ferrate(III) Complex.

Electrocrystallization of the bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) organic donor in the presence of the [Fe(ClCNAn)] tris(chlorocyananilato)ferrate(III) paramagnetic anion in different stoichiometric ratios and solvent mixtures afforded two different hybrid systems formulated as [BEDT-TTF][Fe(ClCNAn)]·3HO () and [BEDT-TTF][Fe(ClCNAn)]·2CHCN () (An = anilato). Compounds and present unusual structures without the typical segregated organic and inorganic layers, where layers of are formed by Λ and Δ enantiomers of the anionic paramagnetic complex together with mixed-valence BEDT-TTF tetramers, while layers of are formed by Λ and Δ enantiomers of the paramagnetic complex together with dicationic BEDT-TTF dimers and monomers. Compounds and show semiconducting behaviors with room-temperature conductivities of ca.

Conducting Anilate-Based Mixed-Valence Fe(II)Fe(III) Coordination Polymer: Small-Polaron Hopping Model for Oxalate-Type Fe(II)Fe(III) 2D Networks.

The mixed-valence FeFe 2D coordination polymer formulated as [TAG][FeFe(ClCNAn)]·(solvate) 1 (TAG = tris(amino)-guanidinium, ClCNAn = chlorocyanoanilate dianionic ligand) crystallized in the polar trigonal space group P3. In the solid-state structure, determined both at 150 and at 10 K, anionic 2D honeycomb layers [FeFe(ClCNAn)] establish in the ab plane, with an intralayer metal-metal distance of 7.860 Å, alternating with cationic layers of TAG.

Direct Evidence of Lithium Ion Migration in Resistive Switching of Lithium Cobalt Oxide Nanobatteries.

Lithium cobalt oxide nanobatteries offer exciting prospects in the field of nonvolatile memories and neuromorphic circuits. However, the precise underlying resistive switching (RS) mechanism remains a matter of debate in two-terminal cells. Herein, intriguing results, obtained by secondary ion mass spectroscopy (SIMS) 3D imaging, clearly demonstrate that the RS mechanism corresponds to lithium migration toward the outside of the Li CoO layer.

Decoupling anion-ordering and spin-Peierls transitions in a strongly one-dimensional organic conductor with a chessboard structure, (-MeTTF)NO.

A mixed-valence conducting cation radical salt of the unsymmetrically substituted -MeTTF donor molecule (TTF is tetrathiafulvalene) was obtained upon electrocrystallization in the presence of the non-centrosymmetric NO anion. It crystallizes at room temperature in the monoclinic 2/ space group, with the anion disordered on an inversion centre. The donor molecules are stacked along the axis.

Neutral, closed-shell nickel bis(2-alkylthio-thiazole-4,5-dithiolate) complexes as single component molecular conductors.

Neutral nickel bis(dithiolene) complexes, because of their closed-shell character, are usually considered as insulating materials, unless they are formed out of highly delocalized tetrathiafulvalenedithiolate ligands. We describe here an original series of S-alkyl substituted neutral bis(thiazole-4,5-dithiolate) nickel complexes formulated as [Ni(RS-tzdt)2] (R = Me, Et), which organize in the solid state into uniform stacks and exhibit semiconducting behavior, with room temperature conductivities comparable to those reported in the prototypical [Ni(dmit)2] and [Ni(Et-thiazdt)2] neutral complexes. These findings provide new perspectives in the current search for single component molecular conductors.

Synthesis and Physical Properties of Purely Organic BEDT-TTF-Based Conductors Containing Hetero-/Homosubstituted Cl/CN-Anilate Derivatives.

Radical cation salts composed of a bis(ethylenedithio)tetrathiafulvalene (ET) donor with homo-/heterosubstituted Cl/CN anilic acids as purely organic molecular conducting materials formulated as [BEDT-TTF][HClCNAn] (1) and [BEDT-TTF][HClAn] (2) have been prepared by electrocrystallization. Compounds 1 and 2 crystallized in the monoclinic space group P2/c for 1 and I2/a for 2, showing segregated donor-anion layers arranged in a α'-type donor packing pattern (1) and twisted parallel columns (2), respectively. Single-crystal conductivity measurements show that 1 is a semiconductor with room-temperature conductivity of 10 S cm and an activation energy E of 1900 K.

Subtle Steric Differences Impact the Structural and Conducting Properties of Radical Gold Bis(dithiolene) Complexes.

Among single component molecular conductors, neutral radical gold dithiolene complexes [(R-thiazdt) Au] derived from the N-alkyl-1,3-thiazoline-2-thione-4,5-dithiolate (R-thiazdt) ligand provide an extensive series of conducting, non-dimerized, half-filled band systems. Analogues of the known R=isopropyl (iPr) derivative were investigated here with R=NMe , cyclopropyl (cPr) and n-propyl (nPr), aiming at rationalizing the different solid state structures adopted by these compounds despite very closely related substituents on the heterocyclic nitrogen atom. An original crisscross organization within dimerized chains is observed with R=NMe , differing however from the analogous iPr derivative by a 180° rotation of the heterocyclic nitrogen substituent.

Anion size control of the packing in the metallic versus semiconducting chiral radical cation salts (DM-EDT-TTF)XF (X = P, As, Sb).

Control of the structural type in metallic enantiopure and racemic radical cation salts is achieved through hydrogen bonding interactions between the chiral donor DM-EDT-TTF and the XF anions (X = P, As, Sb), determined by the anion size and the chiral information.

Single-Component Conductors: A Sturdy Electronic Structure Generated by Bulky Substituents.

While the introduction of large, bulky substituents such as tert-butyl, -SiMe3, or -Si(isopropyl)3 has been used recently to control the solid state structures and charge mobility of organic semiconductors, this crystal engineering strategy is usually avoided in molecular metals where a maximized overlap is sought. In order to investigate such steric effects in single component conductors, the ethyl group of the known [Au(Et-thiazdt)2] radical complex has been replaced by an isopropyl one to give a novel single component molecular conductor denoted [Au(iPr-thiazdt)2] (iPr-thiazdt: N-isopropyl-1,3-thiazoline-2-thione-4,5-dithiolate). It exhibits a very original stacked structure of crisscross molecules interacting laterally to give a truly three-dimensional network.

Localization versus Delocalization in Chiral Single Component Conductors of Gold Bis(dithiolene) Complexes.

The first examples of chiral single component conductors are reported. Both (S,S) and (R,R) enantiomers of 5,6-dimethyl-5,6-dihydro-1,4-dithiin-2,3-dithiolate (dm-dddt) ligand have been used to prepare anionic metal bis(dithiolene) complexes formulated as ([(n-Bu)4N][M(dm-dddt)2] (M = Au, Ni), which are isostructural according to single crystal X-ray analysis. Single crystal transport measurements indicate semiconducting behavior for the anionic radical Ni complexes, with low room temperature conductivity values and high activation energies.

Correlating conduction properties with the molecular symmetry: segregation of Z and E isomers in the charge-assisted, halogen-bonded cocrystal [(Z,E)-Me2I2TTF]2Br.

The Z and E isomers of the iodinated TTF derivative (Z,E)-Me2I2-TTF co-crystallize in a mixed-valence salt with Br(-) anions, and are segregated into Z and E stacks, each of them with a different charge localization pattern, which also revealed charge-assisted halogen bonding.

Gold dithiolene complexes: easy access to 2-alkylthio-thiazoledithiolate complexes.

In the presence of MeI or EtI, N-tert-butyl-1,3-thiazoline-2-thione derivatives undergo a transformation to 2-alkylthio-thiazoledithiolate pro-ligands with elimination of the tert-butyl substituent. The corresponding Au(III) dithiolene complexes [Au(RS-tzdt)2](-) (R = Me, Et) oxidize readily to the neutral radical species, such as the semi-conducting [Au(EtS-tzdt)2]˙, which organizes into dimers in the solid state.

Molecular Alloys of Neutral Gold/Nickel Dithiolene Complexes in Single-Component Semiconductors.

Control of band filling or doping of molecular (semi)conductors can be performed by substitutional insertion of molecules with a similar shape but a different electron count, with one more or one less electron. This strategy has been explored here within the semiconducting, single-component, radical gold dithiolene complex [AuOC4] bearing para-butoxyphenyl substituents. Alloying with the corresponding neutral nickel dithiolene complex [NiOC4] lacking one electron afforded a complete isostructural series [NiOC4]1-x[AuOC4]x, spanning the whole composition range from x = 0 to x = 1 by 0.

Approaching the limit of Cu(II)/Cu(I) mixed valency in a Cu(I)Br2-N-methylquinoxalinium hybrid compound.

A novel 1D hybrid salt (MQ)[CuBr2]∞ (MQ = N-methylquinoxalinium) is reported. Structural, spectroscopic and magnetic investigations reveal a minimal Cu(II) doping of less than 0.1%.