TY - JOUR
T1 - Kinetic versus thermodynamic control during the formation of [2]rotaxanes by a dynamic template-directed clipping process
AU - Horn, Matthias
AU - Ihringer, Johannes
AU - Glink, Peter T.
AU - Stoddart, J. Fraser
PY - 2003/9/5
Y1 - 2003/9/5
N2 - A template-directed dynamic clipping procedure has generated a library of nine [2]rotaxanes that have been formed from three dialkylammonium salts - acting as the dumbbell-shaped components-and three dynamic, imino bond-containing, [24]crown-8-like macrocycles - acting as the ring-shaped components - which are themselves assembled from three dialdehydes and one diamine. The rates of formation of these [2]rotaxanes differ dramatically, from minutes to days depending on the choice of dialkylammonium ion and dialdehyde, as do their thermodynamic stabilities. Generally, [2]rotaxanes formed by using 2,6-diformylpyridine as the dialdehyde component, or bis(3,5-bis(trifluoromethyl)benzyl)ammonium hexafluorophosphate as the dumbbell-shaped component, assembled the most rapidly. Those rotaxanes containing this particular electron-deficient dumbbell-shaped unit, or 2,5-diformylfuran units in the macroring, were the most stable thermodynamically. The relative thermodynamic stabilities of all nine of the [2]rotaxanes were determined by competition experiments that were monitored by 1H NMR spectroscopy.
AB - A template-directed dynamic clipping procedure has generated a library of nine [2]rotaxanes that have been formed from three dialkylammonium salts - acting as the dumbbell-shaped components-and three dynamic, imino bond-containing, [24]crown-8-like macrocycles - acting as the ring-shaped components - which are themselves assembled from three dialdehydes and one diamine. The rates of formation of these [2]rotaxanes differ dramatically, from minutes to days depending on the choice of dialkylammonium ion and dialdehyde, as do their thermodynamic stabilities. Generally, [2]rotaxanes formed by using 2,6-diformylpyridine as the dialdehyde component, or bis(3,5-bis(trifluoromethyl)benzyl)ammonium hexafluorophosphate as the dumbbell-shaped component, assembled the most rapidly. Those rotaxanes containing this particular electron-deficient dumbbell-shaped unit, or 2,5-diformylfuran units in the macroring, were the most stable thermodynamically. The relative thermodynamic stabilities of all nine of the [2]rotaxanes were determined by competition experiments that were monitored by 1H NMR spectroscopy.
KW - Crown compounds
KW - Dynamic covalent chemistry
KW - Rotaxanes
KW - Self-assembly
KW - Supramolecular chemistry
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U2 - 10.1002/chem.200204479
DO - 10.1002/chem.200204479
M3 - Article
C2 - 12953190
AN - SCOPUS:0141761378
SN - 0947-6539
VL - 9
SP - 4046
EP - 4054
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 17
ER -