Supramolecular Organization and Magnetic Properties of Mesogen-Hybridized Mixed-Valent Manganese Single Molecule Magnets (Mn8Mn4O12)-Mn-III-O-IV(L-x,L-y,L-z-CB)(16)(H2O)(4)

Single molecule magnets (SMM) may be considered for the construction of future integrated nano-devices, provided however that some degree of ordering is imparted to these molecules (surfaces nanostructuration). Combining such nanoobjects with liquid-crystalline orderings to control their assembly and to potentially address them individually therefore appears as one promising strategy. Four mesomorphic, mixed-valent [(Mn8Mn4O12)-Mn-III-O-IV(L-x,L-y,L-z-CB)(16)(H2O)(4)] SMM, differing in the number of liquid-crystalline promoters, (L-x,L-y,L-z-CB), were synthesized, and their self-organizing and magnetic properties were investigated. The influence of the peripheral modifications, and precisely how supramolecular ordering and magnetic properties may be affected by the evolution of the proto-mesogenic cyanobiphenyl-based ligands substitution pattern, was explored. Small-angle X-ray scattering studies revealed that all of the hybridized clusters self-organize into room-temperature bilayer smectic phases, mandated by the specific mesogenic functionalization and that the polymetallic cores are further organized according to a short-range pseudo-2D lattice with hexagonal and/or square symmetry. All mesomorphous hybridized dodecamanganese complexes still behave as SMM: they exhibit blocking of the magnetization at about 2.6 K as evidenced by the occurrence of frequency-dependent out-of-phase ac susceptibility signals as well as an opening of the hysteresis cycle with coercive fields varying between 0.13 and 0.6 T, depending on the surface ligands topology. Comparison of the magnetic properties within this series reveals intricate correlations between the structural features of the mesomorphous molecule magnet (i.e., symmetry of the ligands substitution patterns, molecular conformation, average intercluster distances, and respective inclination) with respect to the relative proportion of slow- and fast-relaxing species and the absolute values of the coercive fields

Stacking of Self-Assembled Surface Micelles in Ultrathin Films

Nonpolar fluorophilic/lipophilic tetrablock amphiphiles are investigated on the surface of water and on solid substrates using compression isotherms, Brewster angle microscopy, and atomic force microscopy. At low pressures, the tetrablocks form monolayers of closely packed surface hemimicelles. Further compression causes a 2D/3D transition. At the end of the plateau, half of the deposited material is expelled forming a second monolayer on top of the initially formed monolayer. Both layers of the films consist of surface micelles, thus providing the first example of spontaneous or compression-driven stacking of self-assembled nano-objects

Langmuir and Langmuir-Blodgett Films from Amphiphilic Pillar[5]arene-Containing [2]Rotaxanes

Amphiphilic pillar[5]arene-containing [2]rotaxanes have been prepared and fully characterized. In the particular case of the [2]rotaxane incorporating a 1,4-diethoxypillar[5]arene subunit, the structure of the compound was confirmed by X-ray crystal structure analysis. Owing to a good hydrophilic/hydrophobic balance, stable Langmuir films have been obtained for these rotaxanes and the size of the peripheral alkyl chains on the pillar[5]arene subunit has a dramatic influence on the reversibility during compression-decompression cycles. Indeed, when these are small enough, molecular reorganization of the rotaxane by gliding motions are capable of preventing strong - interactions between neighboring macrocycles in the thin film

Super-Elastic Air/Water Interfacial Films Self-Assembled from Soluble Surfactants

We show that water-soluble monosodic salts of F-alkyl phosphates CnF2n+1(CH2)(2)OP(O)(OH)(2), with n = 8 and 10 (F8H2Phos and F10H2Phos) form Gibbs films with exceptionally high dilational viscoelastic modules E that reach similar to 900 mN m(-1) in the condensed phases. These E values are up to one order of magnitude larger than those recorded for phospholipid, protein and polymer films commonly considered as highly viscoelastic. F8H2Phos.1Na undergoes a transition between a liquid-expanded and a liquid-condensed phase. In the case of F10H2Phos.1Na, a transition occurs between a gas phase of surface domains, in which the molecules are densely packed, and a liquid-condensed phase

Control of the transition temperatures of metallomesogens by specific interface design: application to Mn-12 single molecule magnets:

Reaction of the Single Molecule Magnet [Mn12O12(CH3-CO2)(16)(H2O)(4)] (Mn-12) with mesogenic dendritic ligands Li (i = 4, 5) quantitatively yields functional clusters [Mn12O12(Li-H)(16)(H2O)(4)] (i = 4, 5) that self-organize into a thermotropic SmA-type liquid crystalline phase. The perturbation of the molecular interface by methylation of the terminal mesogenic cyanobiphenyl groups induces a significant decrease of the clearing temperature without affecting the magnetic properties and the supramolecular organization of the Mn-12-based clusters

Orienting the Demixion of a Diblock-copolymer Using 193 nm Interferometric Lithography for the Controlled Deposition of Nanoparticles

DUV interferometric lithography and diblock copolymer self-organization have successfully been combined to provide a simple and highly collective nanopatterning technique enabling the organization of nanoparticles over several orders of magnitude, from nanometre to millimetre. The nanostructural changes at the surface of the polymer film after thermal annealing have been monitored by AFM and the process parameters optimized for obtaining a long-range organization of the lamellar domains. In particular, the impact of the annealing conditions and geometric parameters of the substrate patterns have been investigated. The nanopatterns resulting from the lamellar demixion of (PS-b-MMA) were used for a controlled deposition of nanoparticles. The affinity of the hydrophobic particles for the PS block was demonstrated, opening new doors towards the preparation of high-density arrays of nanoparticles with potential applications in data storage

Magnetic Properties of Gold Nanoparticles: A Room-Temperature Quantum Effect:

Persistent currents: The magnetism of Au nanoparticles might result from persistent currents. Limited portions of a given sample may even support self‐sustained currents, thus exhibiting remnant magnetization and hysteresis. Observing such a quantum effect at room temperature with user‐friendly samples opens unforeseen possibilities