Two-dimensional homonuclear (COSY, phase-sensitive double quantum filtered COSY) and heteronuclear shift correlated experiments were employed to characterize fully the cylindrical cage ligand 12-hexadecyl-7,17,22,27-tetraoxa-1,4,10,14-tetraazatricyclo[12.5.5.54,10] nonacosane (1) and its sodium, potassium and silver complexes. 13C NMR variable temperature experiments indicated that the free ligand 1 is a mobile molecule in a fast conformational equilibrium at room temperature, whereas its sodium complex is more rigid, some degrees of freedom being allowed in that part of the molecule featuring the longest bridge. The potassium derivative behaves similarly to its sodium counterpart. For the silver complex the differences observed have been attributed to a stronger interaction of the metal ion with nitrogen atoms.
NMR Investigation of Lipophilic Cage Ligands. Part 2. Structural Assignments and Conformational Properties of the Ligand 12-hexadecyl-7,17,22,27-tetraoxa-1,4,10,14-tetraazatricyclo (12.5.5.54,10) nonacosane and of its Sodium, Potassium & Silver Complexes
MOLINARI, Henriette;
1987-01-01
Abstract
Two-dimensional homonuclear (COSY, phase-sensitive double quantum filtered COSY) and heteronuclear shift correlated experiments were employed to characterize fully the cylindrical cage ligand 12-hexadecyl-7,17,22,27-tetraoxa-1,4,10,14-tetraazatricyclo[12.5.5.54,10] nonacosane (1) and its sodium, potassium and silver complexes. 13C NMR variable temperature experiments indicated that the free ligand 1 is a mobile molecule in a fast conformational equilibrium at room temperature, whereas its sodium complex is more rigid, some degrees of freedom being allowed in that part of the molecule featuring the longest bridge. The potassium derivative behaves similarly to its sodium counterpart. For the silver complex the differences observed have been attributed to a stronger interaction of the metal ion with nitrogen atoms.
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