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

The complex forming ability of delta -cyclodextrin delta -CD with 7 kinds o f 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- an d PCD 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 atom s in the ring, while no such precipitates were obtained with smaller MCCs w ith only 8-10 carbon atoms in the ring. The formation of the solid complexe s was confirmed by powder X-ray diffractometry and differential scanning ca lorimetry, The cell dimensions of cycloundecanone (11 carbon atoms in the r ing)/delta -CD complex were determined by X-ray crystallography. The prelim inary crystal data were: Monoclinic, P2(1), a=32.50 (2) Angstrom, b=19.02 ( 3) Angstrom, c=16.60 (1) Angstrom, beta =98.37 (5)degrees, V=10148 (16)Angs trom (3).