In aqueous solutions, thiacalixarene (TCAS) and Ln III (= Nd III, Yb III) self-assembled over a long period of time (1 d) to form 3:2 complexes Ln III 3·TCAS 2 in which the Ln III 3 core is sandwiched between two TCAS ligands, which results in a high kinetic stability. This was not expected from the exo-coordination fashion of TCAS with the O,S,O donors found in the 1:1 complex Ln III·TCAS, and thus this feature was attributed to the multiple bonds between the Ln III 3 core and TCAS. Our observations open an exciting possibility of designing kinetically stable Ln III complexes by using exo-type ligands as scaffolds to sandwich a multi-Ln III core rather than endo-type ones to encapsulate a Ln III core. Lanthanides(III) (Ln = Nd, Yb) and thiacalixarene (TCAS) self-assembled in water to form Ln 3·TCAS 2, over a period of 1 d. The high kinetic stability of Ln 3·TCAS 2 revealed by HPLC was unexpected from the tridentate coordination fashion of TCAS in Ln·TCAS. This suggests a new way to design kinetically stable complexes through the formation of clusters.
ASJC Scopus subject areas
- Inorganic Chemistry