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Comparative Crystal Structure Studies on Distortion of iso -Butyl(aqua)cobaloxime Induced by α-Cyclodextrin and β-Cyclodextrin Hosts

1998; American Chemical Society; Volume: 37; Issue: 24 Linguagem: Inglês

10.1021/ic980378m

1520-510X

Lai-bin Luo, Ying Chen, Hui-Lan Chen, Ze-Ying Zhang, Zhong-Yuan Zhou, Thomas C. W. Mak,

Heme Oxygenase-1 and Carbon Monoxide

The crystal and molecular structures of iso-butyl(aqua)cobaloxime (I) and its hydrated inclusion complexes with α-cyclodextrin (II) and β-cyclodextrin (III) were determined by X-ray diffraction analyses. Crystal data for I: P21/c, a = 30.450(1) Å; b = 9.659(2) Å; c = 19.200(2) Å; β = 107.23(3)°; Z = 12. Crystals of II·H2O and III·9H2O both crystallize in space group P212121 with Z = 4; a = 13.847(1) Å, b = 19.418(1) Å, c = 24.593(1) Å for II·8H2O, and a = 28.188(6) Å, b = 15.190(3) Å, c = 19.017(4) Å for III·9H2O. In the inclusion complexes, the Co(DH)2 unit is located near the wide opening of the cyclodextrin with its iso-butyl group inserted into the cyclodextrin cavity. The structure and conformation changes of the iso-butyl(aqua)cobaloxime are probably related to the noncovalent interaction between the iso-butyl group and cyclodextrin cavity, and steric interaction between cobaloxime and cyclodextrin rims. Our results also show that distortions of iso-butyl(aqua)cobaloxime/cyclodextrin induced by α-CD and β-CD occur in different extent, which assumedly is due to the different cavity diameters of the cyclodextrins.