Probing the tolerance of cucurbit[7]uril inclusion complexes to small structural changes in the guest.

The binding properties of the cucurbit[7]uril host with three structurally related ferrocene-containing guests, ferrocenyltrimethylammonium, ferrocenylmethyltrimethylammonium and ferrocenylethyltrimethylammonium, have been investigated using (1)H NMR spectroscopy, mass spectrometry, voltammetry and computational methods. The experimental and computational data indicate that the stability of the cucurbit[7]uril inclusion complexes is relatively insensitive to the number of methylenes connecting the trimethylammonium and the ferrocenyl groups, although some of their properties are affected in significant ways.