Issue 23, 2002
From the journal:

Journal of the Chemical Society, Dalton Transactions

A p-tert-butylcalix[6]arene bearing phosphinoyl pendant arms for the complexation and sensitisation of lanthanide ions†

Flor de María Ramírez,ab   Sabi Varbanov,ac   Corine Cécile,a   Gilles Muller,a   Nicolas Fatin-Rouge,a   Rosario Scopellitia  and  Jean-Claude G. Bünzli*a  

* Corresponding authors

a Institute of Molecular and Biological Chemistry, BCH 1402, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland
E-mail: jean-claude.bunzli@epfl.ch

b Instituto Nacional de Investigaciones Nucleares, Departamento de Química, Km 36.5 Carretera México-Toluca, Salazar, Municipio de Ocoyoacac, C.P. 52045, Edo. de México, México

c Institute of Polymers, Bulgarian Academy of Sciences, BG-1113 Sofia, Bulgaria

Abstract

The new lower rim functionalised macrocycle 5,11,17,23,29,35-hexa-tert-butyl-37,38,39,40,41,42-hexakis(dimethylphosphinoylmethoxy)calix[6]arene (B6bL6) has been synthesised. Temperature dependent 1H and 31P NMR studies indicate a mixture of conformers with a time-averaged C6v symmetry at 405 K in dmso-d6; ΔG≠ values for conformational interconversion processes are equal to 68(1) and 75(2) kJ mol−1 and reveal a semi-flexible macrocycle with alternate in-out cone conformation, a fact confirmed by molecular mechanics and dynamics calculations. B6bL6 crystallises as a dimer where the two calixarenes are linked through hydrogen bonding and surrounded by water and toluene molecules in the lattice. UV-Vis spectrophotometric titration of B6bL6 with La(III) in acetonitrile yields stability constants log β1 = 9.8 and log β2 = 19.6 for the 1 ∶ 1 and 1 ∶ 2 (Ln ∶ B6bL6) species, respectively. The corresponding complexes with La, Eu, Gd and Tb have been isolated and characterised. Lifetime determinations of the Eu(III) and Tb(III) complexes in acetonitrile solution are consistent with no or little interaction of water molecules in the inner co-ordination sphere. The new ligand sensitises reasonably well the luminescence of the Tb(III) (Qabs = 4.8% , τf = 2.1 ms, 1 ∶ 1 complex) and Eu(III) (Qabs = 2.5%, τ = 2.0 ms, 1 ∶ 2 complex) ions.

Graphical abstract: A p-tert-butylcalix[6]arene bearing phosphinoyl pendant arms for the complexation and sensitisation of lanthanide ions

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Article information

DOI
https://doi.org/10.1039/B206238K
Article type
Paper
Submitted
27 Jun 2002
Accepted
24 Sep 2002
First published
28 Oct 2002

J. Chem. Soc., Dalton Trans., 2002, 4505-4513

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A p-tert-butylcalix[6]arene bearing phosphinoyl pendant arms for the complexation and sensitisation of lanthanide ions

F. D. M. Ramírez, S. Varbanov, C. Cécile, G. Muller, N. Fatin-Rouge, R. Scopelliti and J. G. Bünzli, J. Chem. Soc., Dalton Trans., 2002, 4505 DOI: 10.1039/B206238K

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