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The Design of Selective Chelating Agents: 1,3,5‐Trideoxy‐1,3,5‐tris‐(dimethylamino)‐ cis ‐inositol, a Powerful Ligand for Hard and Highly Charged Metal Ions
Author(s) -
Hegetschweiler Kaspar,
Kradolfer Thomas,
Gramlich Volker,
Hancock Robert D.
Publication year - 1995
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.19950010112
Subject(s) - chemistry , steric effects , aqueous solution , deprotonation , ligand (biochemistry) , chelation , metal ions in aqueous solution , potentiometric titration , protonation , metal , reactivity (psychology) , coordination sphere , cyclohexane , tris , molecule , crystallography , stereochemistry , inorganic chemistry , ion , organic chemistry , medicine , biochemistry , receptor , alternative medicine , pathology
A series of compounds containing the mononuclear complexes [M(tdci) 2 ] 3+ (tdci = 1,3,5‐trideoxy‐1,3,5‐tris(dimethylamino)‐ cis ‐inositol, M = Al, Fe, Ga, In) and [M(tdci) 2 ] 4+ (M = Ti, Ge, Sn) was prepared and characterized by elemental analysis, NMR spectroscopy, and FAB mass spectrometry. Characteristic fragmentation reactions in the mass spectra were elucidated. X‐ray analysis of the Al III , Fe III , Ga III , and In III complexes revealed that two neutral, zwitterionic tdci ligands coordinate to the metal cation exclusively through deprotonated alkoxo groups. The six coordinated oxygen donors and the six NH protons form a hydrophilic pocket, whereas the two cyclohexane rings and the twelve methyl groups form two hydrophobic shells. The hydrophilic pocket is filled with twelve water molecules, which are arranged as a second and a third coordination sphere around the metal cation. The reactivity in aqueous solution was investigated by potentiometric measurements. The bis complexes proved to be stable at pH 7. The evaluated formation constants show an increase of stability in the order Al III