H-1-NMR RESPONSE OF MONO[6-(1-PYRIDINIO)-6-DEOXY]-ALPHA-CYCLODEXTRIN TO INORGANIC ANIONS

The chemical shifts (delta) of some H-1 NMR signals given by mono[6-(1-pyridinio)-6-deoxyl-alpha-cyclodextrin (1) in D2O were significantly changed by the addition of alkali salts of chaotropic anions such as Br-, I-, SCN-, N3-, NO3-, and ClO4-. However, only small changes in delta were brought about by the addition of alkali salts of antichaotropic anions such as F-, Cl-, SO42-, H2PO4-, and HPO42-. The addition of the chaotropic anions caused a marked downfield shift in the signal of a C(5)-H located in the interior of the cavity of 1, and a marked upfield shift in the signal of one of the C(6)-H's involved in the unsubstituted glucopyranose rings of 1. These facts indicate that the anions are included within the cavity and attract the pyridinio group of 1 close to the C(6)-H. The signal of the alpha-H's in the pyridinio group showed a significant downfield shift with the addition of the alkali salts of Br-, I-, and SCN-, which form charge-transfer complexes with 1.