Solid state NMR spectroscopy study of molecular motion in cyclomaltoheptaose (β-cyclodextrin) crosslinked with epichlorohydrin

Dry and hydrated insoluble cyclomatohepatose (beta-cyclodextrin, beta-CD) polymers have been investigated by solid state C-13 NMR spectroscopy techniques such as cross polarization/magic angle spinning with dipolar decoupling (CP/MAS), magic angle spinning both with (DD-MAS) and without (MAS) dipolar decoupling and CP/MAS dipolar dephasing (dd-CP/MAS) to allow the assignment of the main C-13 signals. In the solid state, the presence of water in the samples resulted in a better resolution reflecting increased mobility. Two distinct components (crosslinked beta-CD and polymerized epichlorohydrin) have been found. The molecular mobility of these two components has been analyzed in terms of relaxation parameters such as C-13 spin lattice relaxation (T-1) and H-1 spin lattice relaxation in the rotating frame (T-1 rho). The T-1 values of the polymers show that the beta-CD trapped inside the polymers does not seem to undergo changes in its mobility whatever the amount of epichlorohydrin. The addition of water to beta-CD significantly increases the T-1 values reflecting strong interaction between beta-CD and the solvent. The T-1 rho values obtained reflect the homogeneous nature of the materials. (C) 1998 Elsevier Science Ltd. All rights reserved.