Magneto-structural correlations in self-assembled spin-transition nano-architectures of the [][2×2]-grid-type

Abstract The magnetism of a series of tetranuclear complexes of the [ Fe II 4 L 4 ]( BF 4 ) 8 [2×2] -grid-type was investigated, revealing the occurrence of spin-transition (ST) behavior within this class of compounds. The phenomenon depends directly on the nature of the substituent R1 of the ligand L . All FeII ions in compounds with R1 substituents favoring strong ligand fields ( R 1 = H ; OH ) remain completely in the diamagnetic low-spin state. Only the complex bearing R1=Ph exhibits thermally induced ST behavior.

Supramolecular Spintronic Devices: Spin Transitions and Magnetostructural Correlations in[Fe4IIL4]8+[2×2]-Grid-Type Complexes

The magnetism of a series of tetranuclear complexes of the [Fe4IIL4]8+ [2x2]-grid-type was investigated, revealing the occurrence of spin transition behavior within this class of compounds. The phenomenon depends directly on the nature of the substituent R(1) in the 2-position on the central pyrimidine group of the ligand L. All Fe(II) ions in compounds with R(1) substituents favoring strong ligand fields (R(1)=H; OH) remain completely in the diamagnetic low-spin state. Only complexes bearing R(1) substituents attenuating the ligand field by steric (and to a lesser extent electronic) effects (R(1)=Me; Ph) exhibit spin transition behavior triggered by temperature. In general, gradual and inc…

Synthesis, structure and physical characterization of the dimer {[(bpy)2Co]2(TPOA)}4+ (bpy=2,2′-dipyridyl; H2TPOA=N,N′,N′′,N′′′-tetraphenyl oxalamidine)

Abstract The reaction between CoCl 2 , 2,2′-dipyridyl (bpy) and N , N ′, N ′′, N ′′′-tetraphenyl oxalamidine (H 2 TPOA) in a water/ethanol mixture yields the {[(bpy) 2 Co] 2 (TPOA)} 2+ dimer, that is immediately oxidized in aerobic conditions leading to the Co III species {[(bpy) 2 Co] 2 (TPOA)} 4+ . This cation was isolated as the {[(bpy) 2 Co] 2 (TPOA)}(PF6) 4 ( 1 ) salt, that was characterized by X-ray diffraction on single crystals. The dimer is formed by two Co III ions in octahedral coordination bridged by a deprotonated μ 2 -TPOA ligand. The Co III ions appear in its low spin configuration. Thus, the dimers are essentially diamagnetic, as shown by 1 H NMR and magnetic measurements.

Hierarchical Self-Assembly of Supramolecular Spintronic Modules into 1D- and 2D-Architectures with Emergence of Magnetic Properties

Hierarchical self-assembly of complex supramolecular architectures allows for the emergence of novel properties at each level of complexity. The reaction of the ligand components A and B with Fe II cations generates the (2 K 2) grid-type functional building modules 1 and 2, presenting spin-tran- sition properties and preorganizing an array of coordination sites that sets the stage for a second assembly step. Indeed, binding of La III ions to 1 and of Ag I ions to 2 leads to a 1D columnar superstructure 3 and to a wall-like 2D layer 4, respectively, with concomitant modulation of the magnetic properties of 1 and 2. Thus, to each of the two levels of structural complexity generat- ed by the t…

Durch Temperatur, Druck oder Licht induzierter Spinübergang in einer supramolekularen Fe‐[2×2]‐Gitterverbindung

Spin Crossover in a Supramolecular Fe4II [2×2] Grid Triggered by Temperature, Pressure, and Light

A multiplex electronic switch on the molecular level has been realized by using a tetranuclear FeII complex of the [2×2] grid type. The four metal ions can be switched stepwise between their high-spin and low-spin states by temperature, pressure, and light, thus representing a triple level, triple switch system as illustrated in the picture.