[Fe(sal2-trien)][Ni(dmit)2]: towards switchable spin crossover molecular conductors

A cooperative spin transition behaviour with a wide hysteresis loop (30 K) around 240 K has been observed, for the first time, in a salt based on the redox active [Ni(dmit)2]¯, anion and the [Fe(sal2-trien)]+ spin crossover cation.Real Cabezos, Jose Antonio, [email protected]

Adjusting the cation and anion nature in ionic liquids used for the growth control of nanoparticles of organic conductors

Ionic liquids are used for controlling the growth of organic conductors as nanoparticles. We review the conditions of preparation of nanoparticles of conductors derived from tetrathiafulvalene (TTF), tetramethyltetraselenafulvalene (TMTSF) and bis-ethylenedithiotetrathiafulvalene (BEDT-TTF). They are prepared by electrocrystallization using an ionic liquid supporting electrolyte in which the cation plays the role of growth controller and the anion enters the composition of the expected organic conductor. Stable suspensions of nanoparticles are obtained in one case, a valuable characteristic for potential applications in electronic devices

Spin density wave and superconducting properties of nanoparticle organic conductor assemblies

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).-- et al.The magnetic susceptibilities of nanoparticle assemblies of two Bechgaard salts (TMTSF)2PF6 and (TMTSF)2ClO4, have been studied vs temperature and magnetic field. In the bulk these materials exhibit a spin density wave formation (TSDW=12K) and superconductivity (Tc=1.2K), respectively. We show from inductive (susceptibility) measurements that the nanoparticle assemblies exhibit ground-state phase transitions similar to those of randomly oriented polycrystalline samples of the parent materials. Resistivity and diamagnetic shielding measurements yield additional information on the functional nanoparticle structure in terms of stoichiometric and nonstoichiometric composition.This work was supported by NSF-DMR Grants No. 1005293 and No. 1309146, and the NHMFL is supported by NSF Cooperative Agreement No. DMR-1157490, the State of Florida, and the U.S. Department of Energy. I.C. thanks the French Ministére de l’Enseignement Supérieur et de la Recherche (MESR) for a Ph.D. grant.Peer Reviewe

Facile synthesis of nanoparticles of the molecule-based superconductor κ-(BEDT-TTF)2Cu(NCS)2

Well-dispersed roughly spherical nano-objects of the molecule-based superconductor κ-(BEDT-TTF)2Cu(NCS)2 have been prepared in an organic solution by using an easy synthetic route. Long alkyl-chain aconitate esters have been used as growth controlling agents. Nano-objects exhibiting sizes in the 35–120 nm range are made of aggregated individual smaller nanoparticles ranging from 3 to 10 nm. Nanoparticle powders have been studied by X-ray diffraction, high resolution electron microscopy and atomic force microscopy in the conductivity mode. Résumé : Des nano-objets sphériques et bien dispersés du supraconducteur moléculaire κ-(BEDT-TTF)2Cu(NCS)2 ont été préparés en solution organique à l'aide d'une méthode de synthèse relativement aisée. Des aconitates à longue chaîne alkyle ont été utilisés comme régulateurs de croissance. Ces nano-objets de taille comprise entre 35 et 120 nm sont constitués de petites particules dont le diamètre individuel est de l'ordre de 3 à 10 nm. Les poudres nanoparticulaires ont été étudiées par diffraction des rayons X, par microscopie électronique à haute résolution et enfin par microscopie à force atomique en mode conducteur

Nanoparticles of tetrathiafulvalene chloride derivatives grown in the presence of amphiphilic molecules

The work described in this paper is directed towards the electrosynthesis of TTFCl0,77 as spherical nanoparticles by using amphiphilic molecules, behaving as growth-controlling agents. The morphology and the size distribution of the particles were analyzed using transmission electron microscopy and the resulting powders were characterized by infrared and Raman spectroscopy along with X-ray diffraction. In the presence of dodecylamine, electron micrographs evidenced spherical and relatively well-dispersed nanoparticles exhibiting a mean diameter of about 10 nm. However, in the presence of N-octylfurfurylimine, a mixture of nanoparticles and sticks were formed. The best results in terms of smallness of particles size and narrowness size distribution were obtained in the presence of 1-octanamine, N-(2-thienylmethylene). Spherical nanoparticles exhibiting sizes in the 4–12 nm range with an average size of about 8 nm were observed. The nanoparticles powder exhibited a room temperature conductivity of about 0.01 S.cm–1

Molecular conductors as nanoparticles in the presence of long-chain alkyl imidazolium salts or amphiphilic molecules

Nanoparticles of two molecule-based conductors, namely TTF·TCNQ and TTF[Ni(dmit)2]2, have been prepared in organic solution in the presence of ionic or nonionic species bearing a long-chain alkyl group, acting as growth-controlling agents. The size, morphology, and state of dispersion of the nanoparticles depended on the nature of the growth-controlling agent and the reaction temperature. In the presence of a long-chain alkyl-based ionic liquid at −50 °C, electron micrographs evidence that TTF·TCNQ nano-objects are frequently elongated, whereas TTF[Ni(dmit)2]2 nanoparticles are aggregated. In the presence of a neutral long-chain alkyl-based imine at room temperature, nanoparticles are spherical (mean diameter <20 nm) and well dispersed. Vibration spectra evidence that the amounts of charge transfer for TTF·TCNQ and TTF[Ni(dmit)2]2 as nano-objects are very similar to those for the same phases as bulk materials. According to the thermoanalytical investigations, the prepared nanoparticles are stable thermally up to approximately 200 °C, and their decomposition is generally a multi-step process. Their heat treatment results in various sulfur-containing volatiles (CS2, SO2, H2S); moreover, HCN is also detected in the case of nitrogen-containing molecules (TCNQ)

A chirality-induced alpha phase and a novel molecular magnetic metal in the BEDT-TTF/tris(croconate)ferrate(III) hybrid molecular system

The novel paramagnetic and chiral anion [Fe(C5O5)3]32 has been combined with the organic donor BEDT-TTF (= ET = bis(ethylenedithio)tetrathiafulvalene) to yield the first chirality- induced α phase and a paramagnetic metal.Gomez Garcia, Carlos, [email protected] ; Coronado Miralles, Eugenio, [email protected] ; Gimenez Saiz, Carlos, [email protected]

Spin density wave and superconducting properties of nanoparticle organic conductor assemblies

The magnetic susceptibilities of nanoparticle assemblies of two Bechgaard salts (TMTSF)2PF6 and (TMTSF)2ClO4, have been studied vs temperature and magnetic field. In the bulk these materials exhibit a spin density wave formation (TSDW=12K) and superconductivity (Tc=1.2K), respectively. We show from inductive (susceptibility) measurements that the nanoparticle assemblies exhibit ground-state phase transitions similar to those of randomly oriented polycrystalline samples of the parent materials. Resistivity and diamagnetic shielding measurements yield additional information on the functional nanoparticle structure in terms of stoichiometric and nonstoichiometric composition