Ie-Rang Jeon

Tristability in a Light-Actuated Single-Molecule Magnet

Molecules exhibiting bistability have been proposed as elementary binary units (bits) for information storage, potentially enabling fast and efficient computing. In particular, transition metal complexes can display magnetic bistability via either spin-crossover or single-molecule magnet behavior. We now show that the octahedral iron(II) complexes in the molecular salt [Fe(1-propyltetrazole)6](BF4)2, when placed in its high-symmetry form, can combine both types of behavior. Light irradiation under an applied magnetic field enables fully reversible switching between an S = 0 state and an S = 2 state with either up (M(S) = +2) or down (M(S) = -2) polarities. The resulting tristability suggests the possibility of using molecules for ternary information storage in direct analogy to current binary systems that employ magnetic switching and the magneto-optical Kerr effect as write and read mechanisms.

Metal-to-metal electron transfer in Co/Fe Prussian Blue molecular analogues: the ultimate miniaturization.

Co/Fe Prussian Blue analogues are known to display both thermally and light induced electron transfer attributed to the switching between diamagnetic {Fe(II)LS(μ-CN)Co(III)LS} and paramagnetic {Fe(III)LS(μ-CN)Co(II)HS} pairs (LS = low spin; HS = high spin). In this work, a dinuclear cyanido-bridged Co/Fe complex, the smallest {Fe(μ-CN)Co} moiety at the origin of the remarkable physical properties of these systems, has been designed by a rational building-block approach. Combined structural, spectroscopic, magnetic and photomagnetic studies reveal that a metal-to-metal electron transfer that can be triggered in solid state by light, temperature and solvent contents, is observed for the first time in a dinuclear complex.

Self-assembly of [CuIITbIII]3+ and [W(CN)8]3− tectons: a case study of a mixture containing two complexes showing slow-relaxation of the magnetization

The reaction of [Cu(valen)] with Tb(NO(3))(3) and (Bu(3)NH)(3)[W(CN)(8)] affords two types of crystals: [{W(CN)(8)}Cu(valen)Tb(OH(2))(5)]·2H(2)O (1, a discrete trinuclear complex) and [{W(CN)(8)}Cu(valen)Tb(OH(2))(4)]·CH(3)CN·H(2)O (2, an infinite zig-zag chain), both compounds showing slow relaxation of the magnetization (H(2)valen is the Schiff base resulting from the reaction of o-vanillin with 1,2-ethanediamine).

Spin crossover or intra-molecular electron transfer in a cyanido-bridged Fe/Co dinuclear dumbbell: a matter of state†

The design of molecule-based systems displaying tuneable optical and/or magnetic properties under external stimuli has received a great deal of attention in the past few years. This interest is driven by the potential applications in high-performance molecule-based electronics in the areas of recording media, switches, sensors, and displays. As an example, three-dimensional Fe/Co Prussian blue compounds exhibit a concomitant change in magnetic and optical properties due to a temperature- or light-induced metal-to-metal electron transfer. The foregoing remarkable properties in Prussian blues prompted us to design soluble molecular fragments of these coordination networks through a rational building-block approach in order to mimic their properties on a single molecule. With a judicious choice of the ligands for the iron and cobalt molecular precursors, we prepared a dinuclear cyanido-bridged Fe/Co complex that exhibits an unexpected temperature-dependent spin crossover in the solid state while an intramolecular electron transfer triggered by protonation is observed in solution.

Syntheses, Structures, and Magnetic Properties of a Novel mer-[(bbp)FeIII(CN)3]2– Building Block (bbp: bis(2-benzimidazolyl)pyridine dianion) and Its Related Heterobimetallic Fe(III)–Ni(II) Complexes

A new symmetrical tricyanide building block mer-[Fe(bbp)(CN)3](2-) [1; bbp = bis(2-benzimidazolyl)pyridine dianion] has been prepared and structurally and magnetically characterized. It forms a new low-spin meridionally capped {Fe(III)L(CN)3} fragment with the tridentate bbp ligand. The reaction of 1 with Ni(II) salts in the presence of various ancillary ligands affords several new cyanido-bridged complexes: a trinuclear complex {[Ni(ntb)(MeOH)]2[Fe(bbp)(CN)3][ClO4]2}·2MeOH (2), a tetranuclear compound {[Ni(tren)]2[Fe(bbp)(CN)3]2}·7MeOH (3), and a one-dimensional heterobimetallic system: {[Ni(dpd)2]2[Fe(bbp)(CN)3]2}·9MeOH·3H2O (4) [ntb = tris(2-benzimidazolylmethyl)amine, tren = tris(2-aminoethyl)amine, and dpd = 2,2-dimethyl-1,3-propanediamine]. The structural data shows that 2 is a linear complex in which a central Fe(III) ion links two adjacent Ni(II) ions via axial cyanides, while 3 is a molecular square that contains cyanido-bridged Ni(II) and Fe(III) ions at alternate corners. Complex 4 is a one-dimensional system that is composed of alternating cyanido-bridged Ni(II) and Fe(III) centers. Compounds 2-4 display extensive hydrogen bonding and moderately strong π-π stacking interactions in the solid state. Magnetic studies show that ferromagnetic exchange is operative within the Fe(III)LS(μ-CN)Ni(II) units of 2-4.

A Defect Supertetrahedron Naphthoxime-Based [MnIII9] Single-Molecule Magnet

A new [Mn(III)9] complex was synthesized from a naphthoxime-based ligand. It was structurally and magnetically characterized, revealing a rare defect supertetrahedral topology and promising SMM properties with a large energy barrier of 67 K.