Search

Half‐metallic materials are theoretically predicted to be metallic and insulating, which have not been confirmed experimentally, and the predictions are still in doubt. We report the resistance‐chiral anisotropy (R‐ChA), i.e. chirality‐dependent electrical conductivity, in chiral mesostructured Fe3O4 films (CMFFs) grown on the substrates via a hydrothermal method using amino acids as symmetry‐breaking agents. Two levels of chirality exist in the CMFFs: primary distortion of the crystal lattice forms twisted nanoflakes, and secondary helical stacking of nanoflakes forms fan‐shaped nanoplates. At temperatures below 30 K, the CMFFs exhibited metallic conductivity and insulation for one handedness and the other, respectively. The chirality‐dependent effective magnetic fields were speculated to stabilize the opposite spin in the antipodal chiral frame, which led to the free transport of electrons in one handedness of the chiral structure and immobility for the other handedness. [ABSTRACT FROM AUTHOR]

Half‐metallic materials are theoretically predicted to be metallic and insulating, which have not been confirmed experimentally, and the predictions are still in doubt. We report the resistance‐chiral anisotropy (R‐ChA), i.e. chirality‐dependent electrical conductivity, in chiral mesostructured Fe3O4 films (CMFFs) grown on the substrates via a hydrothermal method using amino acids as symmetry‐breaking agents. Two levels of chirality exist in the CMFFs: primary distortion of the crystal lattice forms twisted nanoflakes, and secondary helical stacking of nanoflakes forms fan‐shaped nanoplates. At temperatures below 30 K, the CMFFs exhibited metallic conductivity and insulation for one handedness and the other, respectively. The chirality‐dependent effective magnetic fields were speculated to stabilize the opposite spin in the antipodal chiral frame, which led to the free transport of electrons in one handedness of the chiral structure and immobility for the other handedness. [ABSTRACT FROM AUTHOR]

In order to further optimize our triplesalen‐based single‐molecule magnets, we have synthesized the triplesalophen ligand H6baronMe, where the completely sp2‐hybridized ligand backbone should enable almost planar complexes. Here, we report the new complexes [(baronMe){FeIIICl}3], [(baronMe){FeIII(CN)2}3]3–, and [(baronMe){CrIII(CN)2}3]3–. As intended the local anisotropy axes, defined by the cyanide ligands, deviate only by ten degrees from the molecular C3‐axis. The exchange coupling in [(baronMe){FeIII(CN)2}3]3– is ferromagnetic with J = 2.2 cm–1 but antiferromagnetic in [(baronMe){CrIII(CN)2}3]3– with J = –1.76 cm–1. The ferromagnetic coupling in the FeIII low‐spin complex is rationalized by a good π overlap of the dyz magnetic orbital with the O(pz) orbitals of the central phloroglucinol unit. The three unpaired electrons of the CrIII ions in [(baronMe){CrIII(CN)2}3]3– provide competing spin‐delocalization and spin‐polarization pathways, which explains the overall antiferromagnetic coupling. These two complexes are the first l.s. FeIII and CrIII complexes of triplesalen‐like ligands and emphasize the strong impact of the specific electronic configuration on the spin‐polarization mechanism via the central phloroglucinol. The potential of [(baronMe){FeIII(CN)2}3]3– and [(baronMe){CrIII(CN)2}3]3– as molecular building blocks for nonanuclear complexes by coordination to the six cyanides is discussed. The first trinuclear molecular building blocks [(baronMe){Fe(CN)2}3]3–· and [(baronMe){Cr(CN)2}3]3– with six coordinated cyanide ligands are synthesized. The low spin FeIII complex is ferromagnetically while the CrIII complex is antiferromagnetically coupled which provides a better understanding of the spin‐polarization mechanism. [ABSTRACT FROM AUTHOR]