| Mechanical interlocked molecules,such as rotaxanes,catenanes,molecular knots,have become a hotspot in the last 20 years,not only beacuse of their fantastic supramolecular architectures,but also beacuse of their widely potential applications.Cucurbit[n]urils(CB[n]s)are a series of macrocyclic compounds bearing a rigid hydrophobic cavity and two identical carbonyl fringed portals that have a wide range of applications in molecular recognition.In this paper,different guest molecules have been synthesized.As these guest molecules have different functional groups,they can form different kinds of rotaxanes and pseudorotaxanes with cucurbit[n]urils through noncovalent bonds.We have investigated different forms of host-guest complexes in solid state and liquid state.In this paper,we studied the binding modes of three different forms of rotaxanes,which were the accumulation patterns of solid crystal states and the stimuli-response behavior of molecular necklaces in liquid state,which are listed as follows:1.Three cucurbit[n]uril-based rotaxanes have been synthesized through host-guest interaction.We have studied the rotaxanes formed through the vertical ?-? and the parallel?-? interactions among the bipyridine units in the solid state,in which the pseudorotaxane CB[6]·1 exhibits a very interesting structure that the vertical ?-? interaction between two 4,4'-bipyridine units in the molecule 1 leads to a square helical structure,similar to the conventional square staircase in life.More interestingly,each of the square helical structures is intertwined through ?-? interactions to form a Chinese-knot structure.Furthermore,the thermodynamic stability properties of the rotaxanes were examined by TG and XRD.2.We have synthesized a carbazole derivative with two arms of 4,4'-bipyridine units,and formed a square[5]molecular necklace with CB[8].NMR(1H,COSY,NOSEY,DOSY),UV-vis,DLS and SEM analysis were carried out for studying the property of the molecular necklace. |
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