THE SELF-ASSEMBLY OF A [2]PSEUDOROTAXANE OF ALPHA-CYCLODEXTRIN BY THESLIPPAGE MECHANISM

The kinetics and thermodynamics of the self-assembly of a [2]pseudorot axane comprised of alpha-cyclodextrin and the 1,10-bis[1-(4-tert-butyl pyridinium)]decane dication, by means of a slippage procedure, have be en measured in aqueous solutions using H-1 NMR spectroscopy. The very slow threading of the alpha-cyclodextrin [k(1) = (4.2 +/- 0.3) x 10(-4 ) s(-1) at 25 degrees C] is preceded by a weak inclusion of the tert-b utylpyridinium end group (K-CD = 18 +/- 3 dm(3) mol(-1)). The dissocia tion of the [2]pseudorotaxane occurs with a rate constant of (4.2 +/- 0.2) x 10(-6) s(-1) at 25 degrees C, yielding a pseudorotaxane stabili ty constant of (1.8 +/- 0.2) x 10(3) dm(3) mol(-1).