Lanthanoid complexation by a tris-tetrazole-functionalised calix[4]arene

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John Wiley & Sons, Inc
The synthesis and characterization of 5,11,17,23-tetra-tert-butyl-25-hydroxy-26,27,28-tris(tetrazol-5-ylmethoxy)calix[4]arene is reported. Purification of the macrocycle required the use of preparative HPLC techniques. The macrocycle was found to be a poorer ligand for complexation of lanthanoid cations than the bis(tetrazole) analogue, but somewhat more effective than the tetrakis(tetrazole)-substituted derivative. Two metal complexes of the tris(tetrazole)–calixarene were structurally characterised. A polymeric sodium salt of the tris(tetrazole)–calixarene was isolated from a solution containing yttrium and a sodium acetate buffer. A praseodymium complex was isolated in the presence of an ammonium acetate buffer, where the calixarene acts as a unidentate ligand, bound to the metal atom through one tetrazole N-atom. Increasing the amount of buffer resulted in the crystallisation of a metal-free ammonium salt of the calixarene. © 2016 John Wiley & Sons, Inc.
Rare earths, Complexes, Tetrazoles, Calixarenes, Purification, Ligands, Sodium, Ytterbium
D'Alessio, D., Skelton, B. W., Sobolev, A. N., Krause-Heuer, A. M., Fraser, B. H., Massi, M., & Ogden, M. I. (2016). Lanthanoid complexation by a tris-tetrazole-functionalised calix[4]arene. European Journal of Inorganic Chemistry, 2016(34), 5366-5372. doi:10.1002/ejic.201600938