Study On Synthesis And Properties Of Cucurbituril And Suppamolecular Complexes

Cucurbituril is a macrocyclic cavitand compound with two portals. It has the shape of a cucurbit with oxygen atoms of the carbonyl lying in the bottom. The number of oxygen atoms is the same as that of monomer of glycoluril. It's potential as a "containter" for other molecules has generated interest in a variety of areas, for example, medicine, catalysis, and supramolecular chemistry where rotaxanes and catenanes can serve as large building blocks. In this dissertation, the synthesis of cucurbituril and some supramolecular complexes and some of their properties, including the structure, electrochemical and thermodynamic properties were studied. We hope the results of study can provide theory basis for application.This dissertation employed ultrasound in order to synthesize glycoluril as the raw material for cucurbituril synthesis. The effect of different reaction condition on yield of glycoluril, including relative amounts of reactions(urea and glyoxal),pH, reaction time and dropping rate of glyoxal, were studied. Comparing with the traditional synthesis method, ultrasound synthesis can increase the purity and yield of glycoluril at lower temperatures.Cucurbit[n]uril(n=5,6,8) was synthesized and the structures of the products were determined by proton-nuclear magnetic resonance (1H NMR ) with D2O/KCI replaced D2O/DC1 as solvent. The results show that the change in KC1 from 0.4mol/L to 1.5mol/L has minimal effect on the proton chemical shifts. The peak of crystal water is also little affected. A crystal of C36H36N24O12.7H2O was attained from a solution of sulfuric acid. X-ray diffraction (XRD) characterization reveal that the crystal belongs to six cubic system with R-3 space group symmetry. The crystallographic parameters were as follows: a =b = 3.2017(4) (nm), c = 1.2495(3) (nm),a=p= 90(°),r=120(°),V=11.092(4) (nm3),Z=9,Dc=1.513mg m-3,Mr=1123.00, F(000)= 5274,R=0.1075,Wr=0.2275,u=0.124mm-1. The size of portal diameter is from 0.37nm to 0.435nm. Thermodynamics stability of cucurbit[n]uril (n=5,6,8) was measured by DSC. The result shows that the decomposition temperatures of cucurbit[n]uril(n=5,6,8) are 515.8℃, 490.3℃ and 457.3℃ respectively, decreasing with increasing number of glycoluril units.The electrochemical properties of cucurbit[6]uril were investigated by bulk electrolysis with coulometry and cyclic voltammetry. The result indicats that cucurbit[6]uril has electrochemical activity. The mechanisms of electrode reactions were deduced on a glass carbon working electrode. Two reduction peaks of cucurbit[6]uril are obtained by cyclic voltammetry in 0.5mol/L KNO3 solution. The former is pseudo-reversible and is obtained by redox of nitrogen atom. The latter is completely irreversible peak, which is obtained by the reduction of carbonyl.The electrochemical properties of cucurbit[6]uril complexes with gallium, indium and iron were also investigated. Cucurbit[6]uril complexes with both gallium and indium involve a pseudo-reversible electrode transfer process on a glass carbon working electrode. In contrast, cucurbit[6] uril complex with iron involves a pseudo-reversible and an irreversible electron transfers, and the redox behaviour in the scan range occurs in cucurbit[6]uril and not iron.The properties of cucurbit[6]uril as a ligand coordinated with carmine was studied .The stability constant of complex is 1.38 ×103. The use of cucurbit[6] uril was investigated as a possible decoloring agent for treating wastewater. The results indicate that cucurbituril has a good decolorizing effect, but the overall chemical oxidation demand (COD) of the wasterwater is high.