Preparation Of Briged β-cyclodextrin And Their Inclusion Behavior With Diphenyl Compounds

β-Cyclodextrin(β-CD)has a special internal hydrophobic,external hydrophilic structure that can form inclusion complexes with guest molecules,which can improve the physical and chemical properties of guest molecules after inclusion.However,because of the low solubility ofβ-cyclodextrin in water,its use is limited.Therefore,in order to widen the application range ofβ-cyclodextrin,it can be modified.In recent years,the research on single-modifiedβ-cyclodextrin has become more and more mature,so researchers are paying more and more attention to the study of bridgingβ-cyclodextrin.The best feature ofβ-cyclodextrin derivatives is the use of twoβ-cyclodextrin cavity hydrophobic interactions to synthesize guest molecules in a more stable clathrate.Therefore,the main research content of this paper is to prepare novel single modifiedβ-cyclodextrin and bridgedβ-cyclodextrin,and to study their inclusion behaviors of diphenyl compounds.This article studies the following aspects:1.The structure and properties ofβ-cyclodextrin were summarized,the application ofβ-cyclodextrin and its derivatives and the methods for the synthesis of inclusion complexes were investigated,and the methods for the determination of inclusion ratio and inclusion stability constants were analyzed.2.Twoβ-cyclodextrin derivatives were prepared:sulfanilic acid-β-cyclodextrin(ABS-β-CD)and4,4’-diamino-diphenyl ether-bridgedβ-cyclodextrin(ODA-bis-β-CD)were analyzed by infrared spectroscopy,ultraviolet spectroscopy,nuclear magnetic resonance spectroscopy and elemental analysis.The experimental results show that the synthesis were successful and its can be used as the raw material for the synthesis of inclusion complexes in the next step.3.ODA-bis-β-CD/benzophenone and ABS-β-CD/benzophenone inclusion complexes were prepared by co-precipitation method.The structure were discussed and characterization by IR,UV,~1H NMR and XRD.The inclusion behavior ofβ-cyclodextrin derivatives on benzophenone was studied.The thermodynamic parametersΔG~0,ΔH~0,andΔS~0 were calculated by thermodynamics.The solubilizing effect of twoβ-cyclodextrin derivatives on benzophenone was studied by phase solubility method.Through a series of studies,it was shown that inclusion complexes with an inclusion ratio of 1:1 were formed by UV titration,and the inclusion stability constants K_s were 215.54 L/mol and326.04 L/mol calculated from the H-B equation.The thermodynamic parametersΔG~0<0,ΔH~0<0 andΔS~0<0 indicate that the inclusion process was a self-distributive thermal process,and the enthalpy change was the main driving force of the inclusion reaction.As the concentration ofβ-cyclodextrin derivatives increases,the water solubility of benzophenone increases significantly.At room temperature,when the concentration of ABS-β-CD,ODA-bis-β-CD andβ-CD was 1.2 mmol/L,the solubility of benzophenone in water was increased by 5.86,2.48 and1.75 times respectively.The solubilization coefficient K_c were 3744.64,1128.5,and 594.64,respectively.4.The co-precipitation method was used to prepare ODA-bis-β-CD/diphenyl thiourea and ABS-β-CD/diphenyl thiourea inclusioncomplexes,usinginfraredspectroscopy,UV-vis spectrophotometry,~1H NMR and XRD for characterization.The inclusion behavior ofβ-cyclodextrin derivatives on diphenyl thiourea was studied.The inclusion complexes ofβ-cyclodextrin derivatives with diphenyl thiourea formed an inclusion ratio of 1:1 by UV titration.According to H-B equation,the inclusion stability constants K_s were calculated as228.19 L/mol and 515.78 L/mol.The thermodynamic parametersΔG~0<0,ΔH~0<0,andΔS~0<0 can be calculated by the inclusion stability constants at different temperatures.It can be proved that the inclusion process of the two inclusion complexes was a self-distributive thermal process,and the transformation was the main driver of the inclusion response.The solubilization of diphenyl thiourea with twoβ-cyclodextrin derivatives was studied by phase solubility method.The results showed that with the increase of the concentration ofβ-cyclodextrin derivatives,the water solubility of diphenyl thiourea increased significantly.At room temperature,when the concentration of ABS-β-CD,ODA-bis-β-CD andβ-CD was 1.2 mmol/L,the solubility of diphenyl thiourea in water was increased by 6.36,2.66,and 1.21 times respectively.The solubilization coefficient K_c were 4567.8,1398.2 and 175.0,respectively.