竞争包结法研究印楝素与β-环糊精及其衍生物的选择键合

Selective Binding Behaviors of β-Cyclodextrin and Its Derivatives with Azadirachtin Guests by Competitive Inclusion Method

以酚酞作为光谱探针,采用紫外-可见光谱滴定法测定了β-环糊精(β-CD),单(6-脱氧-乙二胺)-β-环糊精(en-β-CD),单(6-脱氧-二乙基三胺)-β-环糊精(dien-β-CD),七(2,3,6-三-O-甲基)-β-环糊精(TM-β-CD),七(2,6-二-O-甲基)-β-环糊精(DM-β-CD),2-羟丙基-β-环糊精(HP-β-CD)在25℃时,pH=10.5缓冲液中与两种印楝素客体分子所形成超分子配合物的稳定常数。结果表明,多种弱相互作用力协同作用于环糊精的配位过程,主-客体间的尺寸匹配决定所形成配合物的稳定性,环糊精衍生物的取代基影响主体配位能力。6种环糊精主体化合物对印楝素客体分子的包合能力的大小为:HP-β-CD>en-β-CD≈dien-β-CD>β-CD>DM-β-CD≈TM-β-CD。对印楝素A和B给出相似的键合能力。

Spectrophotometric titrations were performed in aqueous buffer solution（pH=10.5） at 25 ℃ to determine the binding constants of β-cyclodextrin（β-CD）,mono（6-ethylene-diamino-6-deoxy）-β-cyclodextrin（en-β-CD）,mono（6-diethylene-triamino-6-deoxy）-β-cyclodextrin（dien-β-CD）,heptakis-（2,6-tri-O-methyl）-β-cyclodextrin（DM-β-CD）,heptakis（2,3,6-tri-O-methyl）-β-Cyclodextrin（TM-β-CD）,and（2-hydroxypropy1）-β-cyclodextrin（HP-β-CD） with azadirachtin guest molecules using phenolphthalein as a spectral probe.The results indicate that several weak interactions cooperatively contribute to the inclusion complexation of the β-cyclodextrin hosts and the complex stability is dominated by the size/shape-matching between host and guest.For azadirachtin,the molecular inclusion ability is HP-β-CD〉en-β-CD≈dien-β-CD〉β-CD〉DM-β-CD≈TM-β-CD.The substituent on the cyclodextrin derivatives changes its original binding ability.Furthermore,the six β-cyclodextrin hosts can also serve as discrimination reagents toward azadirachtin,and have the similar binding constants between azadirachtin A and azadirachtin B.