Complex formation of cyclomaltononaose delta-cyclodextrin (delta-CD) with macrocyclic compounds

The complex forming ability of delta-cyclodextrin delta-CD with 7 kinds of macrocyclic compounds (MCCs) with 8-15 carbon atoms in the ring as models of large guest molecules was studied in aqueous solution and compared with the complexation properties of alpha-, beta- and gamma-CD. Both alpha- and beta-CD formed relatively stable complexes with small MCCs, while gamma- and delta-CD were more efficient in binding larger MCCs. The solid MCC/delta-CD complexes were precipitated with the larger MCCs with 11-15 carbon atoms in the ring, while no such precipitates were obtained with smaller MCCs with only 8-10 carbon atoms in the ring. The formation of the solid complexes was confirmed by powder X-ray diffractometry and differential scanning calorimetry. The cell dimensions of cycloundecanone (11 carbon atoms in the ring)/delta-CD complex were determined by X-ray crystallography. The preliminary crystal data were: Monoclinic, P21, a=32.50 (2)A, b=19.02 (3)A, c=16.60 (1) A, beta3=98.37 (5)degrees, V=10148 (16) A3.