New 1:1:1 complex with N-phenyl pyrrole and nano-cavities

Interesting patterns of complexation of N-phenyl pyrrole (PPR) with α-cyclodextrin (α-CD) and β-cyclodextrin (β-CD) separately and also in binary mixture of both types of cyclodextrins in aqueous solution are reported. PPR forms only one type of 1:1 complex with α-CD with pyrrole group inside the cavity. In β-CD two types of 1:1 complexes with opposite orientations were found to occur and estimation of such complexes has been made by simple new method. A new 1:1:1 complex (α-CD · PPR · β-CD) was observed for the first time. Bigger cavity seems to play a role in binary and ternary complexation.