Enhanced Luminescence properties of mononuclear lanthanide complexes with asymmetric seven-coordination structure are reported for the first time. The lanthanide complexes are composed of a lanthanide ion (Eu III or Tb III ), three tetramethyl heptanedionatos and one triphenyl phosphine oxide. The coordination geometries of the lanthanide complexes are evaluated using single crystal X-ray analyses and shape-measurement calculations. The complexes are categorized to be seven-coordinate monocapped octahedral structure (point group: C3v). The sevencoordinate lanthanide complexes show high intrinsic emission quantum yields, extra-large radiative rate constants and unexpected small non-radiative rate constants. The brilliant luminescence properties are elucidated in terms of the asymmetric coordination geometry and small vibrational quanta related to the thermal relaxation.

Luminescent mononuclear seven-coordinate Eu III complexes, with monocapped-octahedral (point group: C 3v ), monocapped-trigonal-prismatic (C 2v ), and pentagonal-bipyramidal (D 5h ) coordination structures, are reported. The complexes each consist of a Eu III ion, three tetramethylheptanedionates, and a phosphine oxide derivative. Controlling steric hindrance by means of introducing methyl groups into the phosphine oxide ligands resulted in the formation of three types of coordination polyhedral structures. The coordination geometrical struc- [a]

Temperature-dependent luminescence of a dinuclear Eu /Tb complex with a seven-coordinate structure is demonstrated. The dinuclear complex is composed of two lanthanide ions, six tetramethylheptanedionate ligands, and a bidentate phosphine oxide linker ligand. The dinuclear structure of the complex was characterized by single-crystal XRD. Intrinsic 4f-4f emission quantum yields of the dinuclear Eu and Tb complexes were 66 and 61 %, respectively. The luminescence color of the dinuclear Eu /Tb complex changed from red to green with increasing temperature. The thermosensing range based on the ratio of luminescence intensity (A /A ) was 100-450 K. The temperature-dependent luminescence is due to the presence of a ligand-to-metal charge-transfer state.

Magneto optical devices based on the Faraday effects of lanthanide ion have attracted much attention. Recently, large Faraday effects were found in nano-sized multinuclear lanthanide complexes. In this study, the Faraday rotation intensities were estimated for lanthanide nitrates [Ln(III) (NO3 )3 ⋅n H2 O: Ln=Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm) and Eu(III) complexes with β-diketone ligands, using magnetic circular dichroism. Eu ions exhibit the largest Faraday rotation intensity for (7) F0 →(5) D1 transitions, and high-symmetry fields around the Eu ions induce larger Faraday effects. The molecular design for the enhancement of Faraday effects in lanthanide complexes is discussed.

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Passivity of a dual-phase carbon steel with ferrite and martensite phases was investigated in pH 8.4 boric acid-borate buffer solution. The corrosion potential of the dual-phase steel was higher than that of pure martensitic steel and lower than that of pure ferritic steel. In dynamic polarization measurements, the passivity-maintaining current of the dual-phase steel was an intermediate value of those of pure ferritic and martensitic steels. EIS revealed that both the charge transfer resistance and capacitance of the oxide film formed on the dual-phase steel were intermediate between those of pure ferritic and martensitic steels. Although the donor density in the oxide film of the dual-phase steel was similar to that of pure ferritic steel, it was smaller than that of pure martensitic steel. SECM showed that the passive film formed on the martensite phase of the dual-phase steel had better electronic conductivity than that of the passive film formed on the ferrite phase. These differences in local passivity of the dual-phase steel suggested that the passive film formed on the ferrite phase has better passivity but larger scattering of the property than that of the passive film on the martensite phase. The local passivity of the dual-phase steel was strongly dependent on the texture of the substrate material.

Three types of red luminescent Eu(III) complexes with Schiff base and hfa ligands (hfa: hexafluoroacetylacetonate), mononuclear [Eu(hfa)(OAc)(salen)] (OAc: acetate anion, salen: N,N'-bis(salicylidene)ethylenediamine), brick-type [Eu(hfa)(OAc)(salbn)] (salbn: N,N'-bis(salicylidene)-1,4-butanediamine), and polynuclear [Eu(hfa)(OAc)(salhen)] (salhen: N,N'-bis(salicylidene)-1,6-hexanediamine) are reported for white light-emitting diode (LED) devices. Among these complexes, brick-type [Eu(hfa)(OAc)(salbn)] excited by blue light (460 nm) exhibits the photosensitized quantum yield (Φ = 47%) and remarkably high efficiency of sensitization (η = 96%). The efficiency of sensitization is caused by the excited state based on ligand-ligand interaction between the Schiff base and hfa ligands in Eu(III) complexes. To fabricate LED devices, the red luminescent [Eu(hfa)(OAc)(salbn)] was mounted on an InGaN blue LED chip.