This review aims at reporting on very recent developments in syntheses, properties and (future) applications of polymer-layered silicate nanocomposites. This new type of materials, based on smectite clays usually rendered hydrophobic through ionic exchange of the sodium interlayer cation with an onium cation, may be prepared via various synthetic routes comprising exfoliation adsorption, in situ intercalative polymerization and melt intercalation. The whole range of polymer matrices is covered, i.e. thermoplastics, thermosets and elastomers. Two types of structure may be obtained, namely intercalated nanocomposites where the polymer chains are sandwiched in between silicate layers and exfoliated nanocomposites where the separated, individual silicate layers are more or less uniformly dispersed in the polymer matrix. This new family of materials exhibits enhanced properties at very low filler level, usually inferior to 5 wt.%, such as increased Young’s modulus and storage modulus, increase in thermal stability and gas barrier properties and good flame retardancy.

Polymer-layered silicate nanocomposites: preparation, properties and uses of a new class of materials

This critical review will be of interest to the experts in porous solids (including catalysis), but also solid state chemists and physicists. It presents the state-of-the-art on hybrid porous solids, their advantages, their new routes of synthesis, the structural concepts useful for their ‘design’, aiming at reaching very large pores. Their dynamic properties and the possibility of predicting their structure are described. The large tunability of the pore size leads to unprecedented properties and applications. They concern adsorption of species, storage and delivery and the physical properties of the dense phases. (323 references)

Hybrid porous solids: past, present, future

Potential applications of metal-organic frameworks

Transition metal carbides and nitrides (MXenes), a family of two-dimensional (2D) inorganic compounds, are materials composed of a few atomic layers of transition metal carbides, nitrides, or carbonitrides. Ti3C2, the first 2D layered MXene, was isolated in 2011. This material, which is a layered bulk material analogous to graphite, was derived from its 3D phase, Ti3AlC2 MAX. Since then, material scientists have either determined or predicted the stable phases of >200 different MXenes based on combinations of various transition metals such as Ti, Mo, V, Cr, and their alloys with C and N. Extensive experimental and theoretical studies have shown their exciting potential for energy conversion and electrochemical storage. To this end, we comprehensively summarize the current advances in MXene research. We begin by reviewing the structure types and morphologies and their fabrication routes. The review then discusses the mechanical, electrical, optical, and electrochemical properties of MXenes. The focus then turns to their exciting potential in energy storage and conversion. Energy storage applications include electrodes in rechargeable lithium- and sodium-ion batteries, lithium-sulfur batteries, and supercapacitors. In terms of energy conversion, photocatalytic fuel production, such as hydrogen evolution from water splitting, and carbon dioxide reduction are presented. The potential of MXenes for the photocatalytic degradation of organic pollutants in water, such as dye waste, is also addressed, along with their promise as catalysts for ammonium synthesis from nitrogen. Finally, their application potential is summarized.

Applications of 2D MXenes in energy conversion and storage systems

The magnetic properties of many magnetic materials can be controlled by external stimuli. The principal focus here is on the thermal, photochemical, electrochemical, and chemical control of phase transitions that involve changes in magnetization. The molecular compounds described herein range from metal complexes, through pure organic compounds to composite materials. Most of the Review is devoted to the properties of valence-tautomeric compounds, molecular magnets, and spin-crossover complexes, which could find future application in memory devices or optical switches.

Control of magnetic properties through external stimuli.

Preface. 1 Metallocenium Salts of Radical Anion Bis(Dichalcogenate) Metalates (Vasco Gama and Maria Teresa Duarte). 1.1 Introduction. 1.2 Basic Structural Motifs. 1.3 Solid-state Structures and Magnetic Behavior. 1.4 Summary and Conclusions. References. 2 Chiral Molecule-Based Magnets (Katsuya Inoue, Shin-ichi Ohkoshi, and Hiroyuki Imai). 2.1 Introduction. 2.2 Physical and Optical Properties of Chiral or Noncentrosymmetric Magnetic Materials. 2.3 Nitroxide-manganese Based Chiral Magnets. 2.4 Two- and Three-dimensional Cyanide Bridged Chiral Magnets. 2.5 SHG-active Prussian Blue Magnetic Films. 2.6 Conclusion. References. 3 Cooperative Magnetic Behavior in Metal-Dicyanamide Complexes (Jamie L. Manson). 3.1 Introduction. 3.2 "Binary" alpha-M(dca)2 Magnets. 3.3 beta-M(dca)2 Magnets. 3.4 Mixed-anion M(dca)(tcm). 3.5 Polymeric 2D (cat)M(dca)34As, Fe(bipy)3. 3.6 Heteroleptic M(dca)2L Magnets. 3.7 Dicyanophosphide: A Phosphorus-containing Analog of Dicyanamide. 3.8 Conclusions and Future Prospects. References. 4 Molecular Materials Combining Magnetic and Conducting Properties (Peter Day and Eugenio Coronado). 4.1 Introduction. 4.2 Interest of Conducting Molecular-based Magnets. 4.3 Magnetic Ions in Molecular Charge Transfer Salts. 4.4 Conclusions. References. 5 Lanthanide Ions in Molecular Exchange Coupled Systems (Jean-Pascal Sutter and Myrtil L. Kahn). 5.1 Introduction. 5.2 Molecular Compounds Involving Gd(III). 5.3 Superexchange Mediated by Ln(III) Ions. 5.4 Exchange Coupled Compounds Involving Ln(III) Ions with a First-order Orbital Momentum. 5.5 Concluding Remarks. References. 6 Monte Carlo Simulation: A Tool to Analyse Magnetic Properties (Joan Cano and Yves Journaux). 6.1 Introduction. 6.2 Monte Carlo Method. 6.3 Regular Infinite Networks. 6.4 Alternating Chains. 6.5 Finite Systems. 6.6 Exact Laws versus MC Simulations. 6.7 Some Complex Examples. 6.8 Conclusions and Future Prospects. References. 7 Metallocene-based Magnets (Gordon T. Yee and Joel S. Miller). 7.1 Introduction. 7.2 Electrochemical and Magnetic Properties of Neutral Decamethylmetallocenes and Decamethylmetallocenium Cations Paired with Diamagnetic Anions. 7.3 Preparation of Magnetic Electron Transfer Salts. 7.4 Crystal Structures of Magnetic ET Salts. 7.5 Tetracyanoethylene Salts (Scheme 7.2). 7.6 Dimethyl Dicyanofumarate and Diethyl Dicyanofumarate Salts. 7.7 2,3-Dichloro-5,6-dicyanoquinone Salts and Related Compounds. 7.8 2,3-Dicyano-1,4-naphthoquinone Salts. 7.9 7,7,8,8-Tetracyano-p-quinodimethane Salts. 7.10 2,5-Dimethyl-N,N'-dicyanoquinodiimine Salts. 7.11 1,4,9,10-Anthracenetetrone Salts. 7.12 Cyano and Perfluoromethyl Ethylenedithiolato Metalate Salts. 7.13 Benzenedithiolates and Ethylenedithiolates. 7.14 Additional Dithiolate Examples. 7.15 Bis(trifluoromethyl)ethylenediselenato Nickelate Salts. 7.16 Other Acceptors that Support Ferromagnetic Coupling, but not Long-range Order above ~2K. 7.17 Other Metallocenes and Related Species as Donors. 7.18 Muon Spin Relaxation Spectroscopy. 7.19 Mossbauer Spectroscopy. 7.20 Spin Density Distribution from Calculations and Neutron Diffraction Data. 7.21 Dimensionality of the Magnetic System and Additional Evidence for a Phase Transition. 7.22 The Controversy Around the Mechanism of Magnetic Coupling in ET Salts. 7.23 Trends. 7.24 Research Opportunities. References. 8 Magnetic Nanoporous Molecular Materials (Daniel Maspoch, Daniel Ruiz-Molina, and Jaume Veciana). 8.1 Introduction. 8.2 Inorganic and Molecular Hybrid Magnetic Nanoporous Materials. 8.3 Magnetic Nanoporous Coordination Polymers. 8.4 Summary and Perspectives. References. 9 Magnetic Prussian Blue Analogs (Michel Verdaguer and Gregory S. Girolami). 9.1 Introduction. 9.2 Prussian Blue Analogs (PBA), Brief History, Synthesis and Structure. 9.3 Magnetic Prussian Blues (MPB). 9.4 High TC Prussian Blues (the Experimental Race to High Curie Temperatures). 9.5 Prospects and New Trends. 9.6 Conclusion: a 300 Years Old "Inorganic Evergreen". References. 10 Scaling Theory Applied to Low Dimensional Magnetic Systems (Jean Souletie, Pierre Rabu, and Marc Drillon). 10.1 Introduction. 10.2 Non-critical-scaling: the Other Solutions of the Scaling Model. 10.3 Universality Classes and Lower Critical Dimensionality. 10.4 Phase Transition in Layered Compounds. 10.5 Description of Ferromagnetic Heisenberg Chains. 10.6 Application to the Spin-1 Haldane Chain. 10.7 Conclusion. References. Index.

Magnetism: Molecules to Materials IV

Octahedral Co2+ centers have been connected by mu(3)-OH and mu(2)-OH2 units forming [Co-4] clusters which are linked by pyrazine forming a two-dimensional network The two-dimensional layers are bridged by oxybisbenzoate (OBA) ligands giving rise to a three-dimensional structure The [Co-4] clusters bond with the pyrazine and the OBA results in a body-centered arrangement of the clusters, which has been observed for the first time Magnetic studies reveal a noncollinear frustrated spin structure of the bitriangular cluster, resulting in a net magnetic moment of 14 mu B per cluster For T > 32 K, the correlation length of the cluster moments shows a stretched-exponential temperature dependence typical of a Berezinskii-Kosterlitz-Thouless model, which points to a quasi-2D XY behavior At lower temperature and down to 14 K, the compound behaves as a soft ferromagnet and a slow relaxation is observed, with an energy barrier of ca 500 K Then, on further cooling, a hysteretic behavior takes place with a coercive field that reaches 5 Tat 4 K The slow relaxation is assigned to the creation/annihilation of vortex-antivortex pairs, which are the elementary excitations of a 2D XY spin system

Quasi-2D XY magnetic properties and slow relaxation in a body centered metal organic network of [Co4] clusters.

Copper(II) and cobalt(II) dicarboxylate-based layered magnets: influence of π electron ligands on the long range magnetic ordering

Recent advances on the organization and characterization of [Mn12] single molecule magnets (SMMs) on a surface or in 3D are reviewed. By using nonconventional techniques such as X-ray magnetic circular dichroism (XMCD) and scanning tunneling microscopy (STM), it is shown that [Mn12]-based SMMs deposited on a surface lose their SMM behavior, even though the molecules seem to be structurally undamaged. A new approach is reported to get high-density information-storage devices, based on the 3D assembling of SMMs in a liquid crystalline phase. The 3D nanostructure exhibits the anisotropic character of the SMMs, thus opening the way to address micrometric volumes by two photon absorption using the pump-probe technique. We present recent developments such as µ-SQUID, magneto-optical Kerr effect (MOKE), or magneto-optical circular dichroism (MOCD), which enable the characterization of SMM nanostructures with exceptional sensitivity. Further, the spin-polarized version of the STM under ultrahigh vacuum is shown to be the key tool for addressing not only single molecule magnets, but also magnetic nano-objects.

The Quest for Nanoscale Magnets: The example of [Mn12] Single Molecule Magnets.

Mise en evidence de deux sites differents pour les ions Ni(II) et formation de chaines infinies en zig zag. Les donnees magnetiques sont decrites a la fois par des modeles d'echange d'Heisenberg et d'Ising

Structural and magnetic study of tetraaqua(EDTA)dinickel dihydrate [Ni2(EDTA)(H2O)4.cntdot.2H2O]. Alternating Lande factors in a two-sublattice 1D system

Marc Drillon

Papers

Magnetism: Molecules to Materials IV

Quasi-2D XY magnetic properties and slow relaxation in a body centered metal organic network of [Co4] clusters.

Copper(II) and cobalt(II) dicarboxylate-based layered magnets: influence of π electron ligands on the long range magnetic ordering

The Quest for Nanoscale Magnets: The example of [Mn12] Single Molecule Magnets.

Structural and magnetic study of tetraaqua(EDTA)dinickel dihydrate [Ni2(EDTA)(H2O)4.cntdot.2H2O]. Alternating Lande factors in a two-sublattice 1D system