Josephine Kanimozhi A, Alexander V
Department of Chemistry, Loyola College, Chennai-60003, India.
Dalton Trans. 2017 Jul 4;46(26):8562-8571. doi: 10.1039/c7dt01133d.
The luminescent ternary lanthanide(iii) complexes [Ln(DBM)(L1)] and [Ln(DBM)(L2)] (Ln = Eu and Tb) of dibenzoylmethane (DBM) and 2-(2-naphthyl)-1H-imidazo[4,5-f][1,10]phenanthroline (L1) and 2-(2-hydroxy-1-naphthyl)-1H-imidazo[4,5-f][1,10]phenanthroline (L2) are reported in this work. The naphthyl chromophore functionalized imidazophenanthroline ligands L1 and L2 are structurally characterized by using single crystal X-ray diffraction: (L1), a = 14.933(4) Å, b = 7.4965(13) Å, c = 15.999(4) Å, α = γ = 90°, β = 102.670(7)°, V = 1747.4(6) Å, Z = 4, monoclinic, P2/c and (L2), a = 7.8555(11) Å, b = 26.216(4) Å, c = 10.0748(17) Å, α = γ = 90°, β = 96.799(7)°, V = 2060.2(6) Å, Z = 4, monoclinic, P2/n. A photophysical study reveals that the ligands L1 and L2 sensitize europium(iii) emission. The complexes [Eu(DBM)(L1)] and [Eu(DBM)(L2)] exhibit the characteristic emission of the Eu(iii) ion at 298 and 77 K. The terbium(iii) complexes [Tb(DBM)(L1)] and [Tb(DBM)(L2)] exhibit only ligand centred fluorescence at room temperature, while metal centred emission is observed at 77 K. The non-luminescence of the Tb(iii) center at room temperature is due to the proximity of the triplet states of the ligands to the D level of the Tb(iii) ion. DC magnetic susceptibility studies have been conducted on the Tb(iii) complexes in a 1 T field over the temperature range 20-300 K. The complexes display room temperature (300 K) χT values of 9.69 and 10.21 cm mol K, respectively. A gradual decrease in the χT values is observed on reducing the temperature and reached the value of 7.80 and 6.60 cm mol K, respectively, at 20 K. The decrease in the χT values as the temperature is lowered could be attributed to the depopulation of the Zeeman split crystal field levels.
本文报道了二苯甲酰甲烷（DBM）与2-(2-萘基)-1H-咪唑并[4,5-f][1,10]菲啰啉（L1）以及2-(2-羟基-1-萘基)-1H-咪唑并[4,5-f][1,10]菲啰啉（L2）形成的发光三元镧系(iii)配合物[Ln(DBM)(L1)]和[Ln(DBM)(L2)]（Ln = Eu和Tb）。通过单晶X射线衍射对萘基发色团功能化的咪唑菲啰啉配体L1和L2进行了结构表征：（L1），a = 14.933(4) Å，b = 7.4965(13) Å，c = 15.999(4) Å，α = γ = 90°，β = 102.670(7)°，V = 1747.4(6) Å，Z = 4，单斜晶系，P2/c；（L2），a = 7.8555(11) Å，b = 26.216(4) Å，c = 10.0748(17) Å，α = γ = 90°，β = 96.799(7)°，V = 2060.2(6) Å，Z = 4，单斜晶系，P2/n。光物理研究表明，配体L1和L2能敏化铕(iii)的发光。配合物[Eu(DBM)(L1)]和[Eu(DBM)(L2)]在298 K和77 K时呈现铕(iii)离子的特征发射。铽(iii)配合物[Tb(DBM)(L1)]和[Tb(DBM)(L2)]在室温下仅表现出以配体为中心的荧光，而在77 K时观察到以金属为中心的发射。室温下Tb(iii)中心不发光是由于配体的三重态与Tb(iii)离子的D能级接近。在1 T磁场中，对20 - 300 K温度范围内的Tb(iii)配合物进行了直流磁化率研究。这些配合物在室温（300 K）下的χT值分别为9.69和10.21 cm³mol⁻¹K⁻¹。降低温度时，χT值逐渐降低，在20 K时分别达到7.80和6.60 cm³mol⁻¹K⁻¹。χT值随温度降低而减小可归因于塞曼分裂晶体场能级的去极化。
