Mesophase and magnetic behavior in cobalt(II) and iron(II) compounds

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• 作者：Shinya Hayami ; Yoshihiro Kojima ; Daisuke Urakami ; Kazuchika Ohta ; Katsuya Inoue
• 关键词：Metallomesogen ; Spin-crossover ; Liquid crystal
• 刊名：Polyhedron
• 出版年：2009
• 出版时间：22 June 2009
• 年：2009
• 卷：28
• 期：9-10
• 页码：2053-2057
• 全文大小：636 K

文摘

The metal complexes with long alkyl chains [Co(C16-terpy)₃](BF₄)₂ (1) and [Fe(C16-terpy)₂](BF₄)₂ (2) were synthesized and the physical properties of the complex were characterized by magnetic susceptibility, Mössbauer spectroscopy, polarizing optical microscopy, differential scanning calorimetry, and X-ray scattering, where C16-terpy is 4′-hexadecyloxy-2,2′:6′,2′′-terpyridine. Variable-temperature magnetic susceptibility measurements and/or Mössbauer studies revealed that the complex 1 exhibited unique spin transition (T_1/2↓ = 217 K and T_1/2↑ = 260 K) induced by structural phase transition, and the complex 2 was in the low-spin state in the temperature region of 5–400 K before the first mesophase transition. The cobalt(II) and iron(II) complexes exhibited liquid-crystal properties in the temperature range of 371–528 K and 466–556 K, respectively. After mesophase transition, the complex 1 exhibited only slight spin transition (T_1/2↓ = 266 K and T_1/2↑ = 279 K), and the complex 2 was in the low-spin state. The compounds with multifunction, i.e., magnetic property and liquid-crystal properties, are important in the development of molecular materials.