Pseudorotaxanes Based On Grown Ether Derivatives

Host-guest chemistry based on crown ether and their derivatives is an important research field in supramolecular chemistry.Complexation ability of the host-guest system is a decisive aspect in preparation threaded structures.To develop the host-guest threaded structures,supramolecular chemist are designing new hosts and guests with their heart and sole.However,modification of known hosts and guests is also a practical way.The recognition of crown ethers to organic cations has gained extensive attention. Paraquat(N,N'dimethyl-4,4'-bipyridinium) and its derivatives have been widely used as guests in supramolecular chemistry to construct numerous host-guest complexes. Paraquat is not only well known to be aπ-electron acceptor but also to be an effective and nonselective herbicide used in more than 100 countries. Bis-p-phenylene[34]crown-10(BPP34C10) is a commonly used host for paraquat. Based on BPP34C 10,we devised a 1,4-benzo- 1,5-naphtho[36]crown- 10-based crown ether.By introducing two COO~- anionic groups into the host,we make the host water-soluable.What's more,by introducing a naphthalene group into the host,we make the host fluorescent.The fluorescence intensity was quenched when paraquat was added into the water solution of the host.The studies may provide a potential method for the fluorescence detection of paraquat in water.Anion-templation,with the strong ion-paring strength and ion-recognition,has assisted the preparation of pseudorotaxanes.The control of host-guest complexation strength by adding or removing anions provids a new way to design novel molecular machines.