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A fluid nematic-like phase is induced in monodisperse iron oxide nanoparticles with a diameter of 3.3 nm. This supramolecular arrangement is governed by the covalent functionalization of the nanoparticle surface with cyanobiphenyl-based ligands as mesogenic promoters. The design and synthesis of these hybrid materials and the study of their mesogenic properties are reported. In addition, the modifications of the magnetic properties of the hybridized nanoparticles are investigated as a function of the different grafted ligands. Owing to the rather large interparticular distances (about 7 nm), the dipolar interaction between nanoparticles is shown to play only a minor role. Conversely, the surface magnetic anisotropy of the particles is significantly affected by the surface derivatization.

New liquid-crystalline protodendritic oligomers with dimesogenic side arms are reported. These “starlike” tetrapedes were obtained by modular synthesis involving the sequential association of different anisotropic promesogenic units within the molecular architecture. This synthetic methodology allowed to prepare tetrapedal oligomers with homolithic (all identical blocks) and conjugated heterolithic (different blocks) structures. The mesomorphism was largely influenced by the peripheral aliphatic chain substitution and to a lesser extent by the chemical nature of the primary constitutive building bricks (tolane and/or stilbene fragments). Indeed, depending on the number of terminal chains grafted onto the terminal mesogens, either columnar phases, resulting from the one-dimensional stacking of supramolecular disks of ∼3−6 supermolecules in fan conformation, or smectic phases, induced by the lateral two-dimensional registry of the supermolecules in cylindrical conformation, were induced. Some of the branche...

The design, synthesis, and some properties of magnetic nanocrystals of ferrite functionalized by luminescent prodendritic ligands are described. Multipotent hybrids resulting from the coupling of an inorganic nanocore (metallic, alloy, or oxide nanoparticle) embedded in an organic shell currently elicit sustained research activity in various areas of materials science and notably in the development of numerous, potential applications, for example, as relevant building blocks for self-assembled arrays of nanoparticles with magneto-luminescence properties, as magnetically movable luminescent probes, or as platforms for biomedical applications. In this study, we have essentially focused on the covalent functionalization of γ-Fe2O3 magnetic nanoparticles, with an average diameter of 40 nm by engineered luminescent, liquid-crystalline oligo(phenylene vinylene)-based prodendritic ligands. The grafting rate of the various ligands on the oxide surface and the thermal stability and behavior of the hybrids have bee...

In this manuscript, a complete and comprehensive study on main-chain liquid crystalline dendrimers is reported. In order to be able to finely tune, and thus control, the mesomorphism of such multicomponent supermolecules, various structural parameters were systematically modified, such as the core nature and connectivity, the degree and topology of branching, the molecular architecture, the generation, and the chain substitution pattern of the peripherally grafted pro-mesogenic groups. The increase of the molecular complexity and the effects of the structural manipulations proved to be very interesting for the design of multifunctional molecular materials, and provided new types of mesophases, enlarging as such the diversity of liquid crystalline supramolecular organizations.

The effect of surface inorganic−organic interactions on magnetic and structural properties of iron oxide magnetic nanoparticles functionalized by lipophilic stilbene molecules has been investigated. The molecules have been grafted through either phosphonate or carboxylate coupling agents. Mossbauer spectra recorded at 300 and 77K suggest a global composition of Fe2.82O4 for the two types of functionalization. Complementary in-field Mossbauer and SQUID measurements have demonstrated that the nanoparticles consist in a magnetite core surrounded by an oxidized layer. The oxidized shell exhibits a spin canting in the carboxylate case leading to a decrease of the net magnetization of the oxide nanoparticle. No canting occurs in the phosphonate case, and the magnetic properties are therefore preserved. The magnetic properties thus depend on the coupling agent, e.g., surface interactions. This result is of primary importance to tune the magnetic properties of functionalized nanoparticles for biomedical and high ...

The design and the functionalisation of nanoparticles is a promising way to elaborate new functional materials, with combined or coupled properties (magnetic, optical, optoelectronic …). In this context, the direct binding of functional organic conjugated molecules (stilbene derivative) onto the surface of monodisperse Fe 3 O 4 magnetic nanoparticles has been studied. Monodisperse Fe 3 O 4 nanoparticles have been synthesized by adjusting the conditions of precipitation and growth and then stilbene derivatives have been grafted onto the surface of these nanoparticles using either phosphonate or carboxylate groups as coupling agents. The functionalised nanoparticles have been characterized before and after grafting by several techniques (XRD, UV, TEM). Studies have demonstrated that the phosphonate coupling agent allows a higher grafting rate than with the carboxylate coupling agent. The nanoparticles functionalised via carboxylate groups are less stable than those functionalised with phosphonate groups mainly due to a strong P–O–Fe bonding. The coated magnetite nanoparticles retain their intrinsic magnetic properties.

A fluid nematic-like phase is induced in monodisperse iron oxide nanoparticles with a diameter of 3.3 nm. This supramolecular arrangement is governed by the covalent functionalization of the nanoparticle surface with cyanobiphenyl-based ligands as mesogenic promoters. The design and synthesis of these hybrid materials and the study of their mesogenic properties are reported. In addition, the modifications of the magnetic properties of the hybridized nanoparticles are investigated as a function of the different grafted ligands. Owing to the rather large interparticular distances (about 7 nm), the dipolar interaction between nanoparticles is shown to play only a minor role. Conversely, the surface magnetic anisotropy of the particles is significantly affected by the surface derivatization.

There is currently a great interest in the preparation of nanostructured magnetic films possessing well-defined structures and controlled properties. Recent progresses in colloidal nanocrystals synthesis and processing have led to new methods for producing films and superstructures made with these materials. Hybrid films have been prepared by organizing functionalized magnetite nanoparticles in large patterns using the Langmuir Blodgett technique. Magnetite nanoparticles with an average particle diameter of 39nm have been prepared and then coated with amphiphilic molecules. The resulting decorated particles, with a hydrophobic outer layer, have proven suitable for being processed by the LB technique. The microstructure and the compacity of the nanoparticle arrays appear to depend on the nature of the organic moiety used to decorate the nanoparticles (carboxylate or phosphonate end-capped stilbene derivatives).