Study On The Synthesis And Properties Of A New Type Of Rotaxane With Citrulline As The Main Body

Supramolecular chemistry is a supramolecular assembly of aggregates formed by the interaction forces between non-covalent bonds.The Cucurbit[n]urils(Q[n])is an important host compound in the supramolecular chemical.Because of its unique structure,which has a hydrophobic cavity with two opening portals rimmed with identical carbonyl groups,it can selectively bind Organic,inorganic,and biomolecules in solution to form host-guest inclusion complexes or self-assembly supramolecular compound.Cucurbit[n]urils has been used as the basic building unit to band small molecule or other compound matching the structure of cucurbit[n]urils for constructing various cucurbit[n]urils-based supramolecules by using weak non-covalent bond interaction forces.Those compounds have potential application value in many fields,and have potential application prospects in different fields such as materials science,biological sciences,physics,and information science.In this thesis,a series of pyridyl ethylene derivatives,benzoxazole derivatives,bis-naphthol derivatives and capecitabine drug molecules were selected to study the properties of rotaxane formed by self-assembly of guest molecule and cucurbit[n]urils.The properties of self-assembly system were studied by NMR,isothermal calorimetry,ultraviolet absorption spectroscopy,fluorescence spectroscopy,mass spectrometry and other physical and chemical methods.The experimental contents and results are as follows:A series of pseudorotaxanes in water based on Q[7]and bispyridinium ethylene-decane-imidazole with different lengths of aliphatic chains as an axle was synthesized,and explored their properties using ~1H NMR,UV and fluorescence spectroscopies,mass spectrometry,and DLS.the mode of action of pseudorotaxanes could be controlled by changing the amount of Q[7],and the alkyl chain attached to the imidazole nitrogen could also influence the mode of pseudorotaxanes.For G1 and G2 systems,increasing the amount of Q[7]altered the host-guest interaction from a dumbbell-shaped structure([3]pseudorotaxanes)to a[4]pseudorotaxane structure.For the G3 system,increasing the amount of Q[7]changed the dumbbell-shaped structure into a[5]pseudorotaxane structure.This indicated that the alkyl chain attached to the imidazole nitrogen could also influence the mode of pseudorotaxanes.A pharmaceutical intermediate,3-pyridyl benzoxazole derivatives(DIHY),was designed and synthesized as the guest molecule.The self-assembly binding models of tetramethyl cucurbit[6]uril(TMeQ[6]),cucurbit[7]uril(Q[7])and cucurbit[8]uril(Q[8])with DIHY were investigated by ~1H NMR,MS,Isothermal Titration Calorimetry and UV-vis spectrum.The results showed that there are different modes of interaction between these three different cucurbit[n]uril and DIHY.For the TMeQ[6]-DIHY system,the guest molecule is located at the port of the TMeQ[6],while for the Q[7]-DIHY system,the 4,5-dihydro-2H-benzoxazole moiety of the guest molecule reside within the cavity of the Q[7]host,whereas the pyridyl group of DIHY guest remains outside of the portal to form the 1:1 inclusion complexes of pseudorotaxane structure.Nevertheless,the 4,5-dihydro-2H-benzoxazole moiety of two guest molecule is included in the cavity of the Q[8]host in a“face to face”stacking way,while the pyridine group of DIHY is located at the port of the Q[8]to form a 1:2supramolecular structure.The host-guest interaction between capecitabine and i Q[7]/Q[7]was studied by using UV-visible absorption spectroscopy,fluorescence spectroscopy,MALDI-TOF MS and ITC.and the experimental results reavled that iQ[7]/Q[7]was encapsulated into the alkyl chain part of the guest to form a 1:1 pseudorotaxanes structure.Using S/R bis-naphthol as the basic unit,a axle molecule with pH response was synthesized.The interaction mode of Q[7]-R-BNH/S-BNH was explored using UV-visible absorption spectroscopy,isothermal titration calorimetry,matrix-assisted in aqueous solution.MALDI-TOF mass spectra,nuclear magnetic resonance spectroscopy and circular dichroism techniques.The experimental results showed that when the external environment is neutral or acidic,the alkyl chain portion of the binaphthol derivative is included in the cavity of the Q[7]in a 2:1 portion.While pH>8,the pyridyl group of the binaphthol derivative is located in the cavity of the Q[7]in a 1:1 portion.It is possible to control the action site of the cucurbit[n]uril on the axis molecule by regulating the pH.