Development of a Selective Synthesis Method and Evaluation of Luminescence Properties of A Heteronuclear Lanthanide-Thiacalixarene Complex

Selective synthesis of a heteronuclear complex based on lanthanide ion (Ln^III) and thiacalix[4]arene-p-tetrasulfonate (TCAS) was achieved by isolation of an intermediate complex (Ln₁TCAS₁) followed by addition of a heteronuclear species Ln'^III. For the Tb-Yb system, the yield of intended heteronuclear complex (Tb₁Yb₂TCAS₂ or Tb₂Yb₁TCAS₂) depended on the balance between the kinetic stability of Ln₁TCAS₁ and reaction rates of the self-assembly to the 3: 2 (Ln: TCAS) complex. As a result, isolation of Yb₁TCAS₁ followed by addition of Tb selectively provided Tb₁Yb₂TCAS₂, which showed diminished Tb luminescence and enhanced Yb^III luminescence as compared to the one for each homonuclear complex (Ln₃TCAS₂). This is suggestive of Tb^III →Yb^III energy transfer, the efficiency of which was estimated to be 26 % from the emission lifetimes of the Tb^III center.