The propensity for aggregation of some modified CDs can be problematic. However, for all the compounds reported here, we saw none of the peak-broadening of the 1 H-NMR spectrum that is typically associated with aggregation. The possibility of aggregation can be further examined with diffusion ordered spectroscopy (DOSY) NMR, a technique used to separate NMR signals based on molecular diffusion coefficients. In particular, a molecule that aggregates will yield a lower diffusion coefficient than one of similar molecular weight that remains monomeric. We carried out DOSY studies of β-CD analogues from each series created here, amic acid, amino acid, urea, and thiourea, in the presence of native β-CD as a control and compared these spectra with that of a covalent β-CD dimer (Compound 21, Figure ), which is larger than any of the derivatives. As shown in Figure , the diffusion coefficients of all derivatives studied in this manner fall between those of native β-CD and the covalent dimer, which is as expected if the derivatives remain monomeric in solution.