Study On The Structure And Properties Of The Inclusion Complex Of Cyclodextrin With Tobacco Flavour

Cyclodextrins(CDs) are a family of macrocyclic oligosaccharides,linked by a -glycosidic bonds.They have a large intramolecular cavity with a cyclindrical shape.Cyclodextrins could form crystalline inclusion complexes with a variety of guest materials.Cyclodextrins have been widely used in the flavour field because of their ability to interact with many flavours through the formation of inclusion complex.The most common flavour application is to enhance the solubility,stability and usability of flavours.The study of supramolecular compounds can help us understand the nature and process of molecular interaction deeply and widely.The inclusion compounds of β-cyclodextrin with vanillin and Cinnamaldehyde were prepared,and the structure of the inclusion compounds were studied by modern analytical methods.The inclusion compounds of β-cyclodextrin with vanillin and Cinnamaldehyde were prepared,and the structural charcterization of the inclusion compounds were studied by UV,IR,X-ray,DSC and NMR.XRD. The mechanism of recognition of vanillin by P -cyclodextrin was investigated using molecular dynamics(MD) methods.The stability constants of inclusion compound of β-cyclodextrin with vanillin in aqueous solution were studied by ultraviolet spectrophotometry at 20 C ,30 C ,40 C and 50 C ,respectively.The apparent thermodynamic parameters were also obtained. The optimum qualitative ratio and stability constant of inclusion compound of hydroxypropye- P -cyclodextrin with vanillin in aqueous solution were studied by ultraviolet spectrophotometry and fluorescence spectrophotometry. The thermal decomposition kinetics of inclusion complex of P-cyclodextrin and Vanillin has been studied by using thermogravimetry.The results demonstrated that van der Waals force(H<0,S<0, governed by H) is the major driving force of inclusion system of vanillin with β-cyclodextrin,and the hydrogen bonding may also play a role. The inclusion complex of hydroxypropye- β-cyclodextrin with vanillin was more stable and this correponds to enclosed depth of vanillin molecule in cavity of host. The crystals of inclusion complexes are of obvious channel-type packing structure,and have specific peak at 1.2nm(about 7 degrees),which indicates formation and purity of inclusion complex. The MD simulations can reproduce the experimental results from structural analysis. And van der Waals force was the major factor of influencing the stability of inclusion complexes.The thermal decomposition was of the first order,and was controlled by Avrami-Erofeev random nucleation and subsequent growth mechanism(A1).The complex thermal stability were dominated by the size/shape-matching between host and guest and hydrogen band interaction,however,the quantitative ratio did not obviously influence the complex thermal stability.