Molecular Recognition Of Bile Salts By Tyrosine Modified Cyclodextrins And The Research Of Luminescent Hydrogel Controlled By Cyclodextrin

Molecular recognition based on cyclodextrins has received much attention in chemistry, biology, environmental science, and many other fields. To further reveal the molecular recognition mechanism of the amino acid modifiedβ-cyclodextrins, twoβ-cyclodextrin derivatives, i.e., L-and D-tyrosine-modifiedβ-cyclodextrin, were synthesized and fully characterized. The single crystal of D-tyrosine-modifiedβ-cyclodextrin was also prepared. Their inclusion modes, binding abilities, and molecular selectivities with four bile salts, i.e., cholic acid sodium salt (CA), deoxycholic acid sodium salt (DCA), glycochoic acid sodium salt (GCA), and taurocholic acid sodium salt (TCA), were investigated by the circular dichroism,2D NMR, and isothermal titration microcalorimetry (ITC). The special interest of this thesis is to reveal thermodynamics of the molecular recognition process. And at the same time, the assembly behavior of a trifurcate complex centered by Ru(II) complex withα,β, andγ-cyclodextrin were studied, respectively. The major contents of this thesis as follows:1.Twoβ-cyclodextrin derivatives, i.e.,L-and D-tyrosine-modifiedβ-cyclodextrin, were synthesized and the single crystal of D-tyrosine-modifiedβ-cyclodextrin was prepared. Its crystal structure was determined by X-ray crystallographic analysis and its assembly behavior in the solid state was studied. The selective binding and molecular recognition behavior between L/D-tyrosine-β-CD with bile salt were researched as key points. The molecular recognition mechanism was discussed from the size/shape fit concept, van der Waals, electrostatic, and hydrophobic interaction between hosts and guests. By compared with L-and D-tryptophan-modifiedβ-cyclodextrin, we got deeply understand the factors governing the molecular recognition of amino acid-modified CDs as well as their thermodynamic origin.2.A trifurcate complex centered by Ru(Ⅱ) complex was synthesized. When it was added to the saturated solution ofα,β, andγ-cyclodextrin, respectively, they could form assemblies with different configuration and the assemblies were carefully studied. Significantly, theα-cyclodextrin/Ru(Ⅱ) complex system formed hydrogel and could be controlled by the temperature, and at the same time, the Ru(Ⅱ) complex system showed the properties of condensation DNA.