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Lipophilic Ligands Derived from 1,3,5‐Triamino‐1,3,5‐trideoxy‐ cis ‐inositol (Taci) for Trivalent Lanthanide Complexation in Aqueous and Organic Solutions
Author(s) -
Delagrange Samuel,
Gateau Christelle,
Chapon David,
Lebrun Colette,
Delangle Pascale,
Vottéro Philippe
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200211)2002:11<2991::aid-ejic2991>3.0.co;2-l
Subject(s) - chemistry , lanthanide , steric effects , tris , aqueous solution , ligand (biochemistry) , nuclear magnetic resonance spectroscopy , stereochemistry , inositol , conjugate , inorganic chemistry , medicinal chemistry , organic chemistry , receptor , ion , mathematical analysis , biochemistry , mathematics
New lipophilic ligands derived from 1,3,5‐triamino‐1,3,5‐trideoxy‐ cis ‐inositol (taci), namely 1,3,5‐trideoxy‐1,3,5‐tris(ethylamino)‐ cis ‐inositol (L 1 ), 1,3,5‐tris(butylamino)‐1,3,5‐trideoxy‐ cis ‐inositol (L 2 ), 1,3,5‐trideoxy‐1,3,5‐tris(hexylamino)‐ cis ‐inositol (L 3 ) have been synthesized by reductive amination of taci. Their complexing properties towards trivalent lanthanide cations, together with those of 1,3,5‐tris(benzylamino)‐1,3,5‐trideoxy‐ cis ‐inositol (L 4 ), have been investigated in solution using mass spectrometry, NMR spectroscopy and potentiometry. It has been shown that each ligand forms trinuclear complexes with the composition [Ln 3 (LH −3 ) 2 ] 3+ . The stability constants (log β 32−6 ) of these complexes have been calculated for Nd 3+ , Eu 3+ , and in some cases for Lu 3+ . The affinity for the lanthanide cations follows the sequence Lu 3+ > Eu 3+ > Nd 3+ , for all the ligands. This sequence follows the well‐known electrostatic trend. The stability of the complex depends on the conjugate effects of the steric hindrance of the substituents and the basicity of the ligands: L 1 ≈ L 2 < taci, in water, and L 3 < L 2 << L 4 , in water/methanol. Among the ligands studied in this work, L 4 appears to be the most effective complexing agent for the lanthanide cations in water/methanol under slightly acidic conditions. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)