From capped to three-dimensional cyclodextrins: the first example of a new class of receptors by trehalose capping of a beta-cyclodextrin

A new capped derivative of cyclomaltoheptaose (CDTHCM) was synthesized by the reaction of 6,6'-dideoxy-6,6' -di(S-cysteamine)-alpha,alpha'-trehalose with 6A,6D-dideoxy-6A,6D-diiodo-cyclomaltoheptaose. The CDTHCM obtained was characterized, together with its behaviour towards protonation. The CDTHCM/ACS (anthraquinone-2-sulfonic acid sodium salt) system was investigated by (HNMR)-H-1 spectroscopy and by i.c.d. (induced circular dichroism) at two different pHs. The deep inclusion of ACS within the CDTHCM cavity, with an association constant about six times larger compared to the beta-CD/ACS system was found at pH 6.