A water soluble negatively charged fluorescent 1,4-benzo-1,5-naphtho-36-crown-10-based host has been devised and synthesized.As shown by proton NMR,ESI mass spectrometry and UV-vis spectroscopy,it binds paraquat with a 1:1 stoichiometry and an association constant of 4.50(±0.02) ×103 M-1 in water.Its complexation with paraquat in water was further investigated by fluorescence emission spectroscopy.The results revealed that when paraquat was added to the water solution of the host,the fluorescence emission of the host was quenched by the charge transfer between the crown ether host and paraquat guest.A similar bis-p-phenylene-34-crown-10-based host was synthesized as a contrasting host.Lacking the naphthalene unit,the second host binds paraquat with a 1:1 stoichiometry and a lower association constant,1.04(±0.04) ×103 M-1,in water.This demonstrated that the naphthalene unit could not only act as a strong fluorescence group but also improve the π-πstacking interactions between the host and guest.
Wu, Ling Liu, Ming Chen, XiaoPeng Li, ShiJun Huang, FeiHe
What is the most favorite and original chemistry developed in your research group?The establishment of two new types of host-guest recognition building blocks(21-crown-7/secondary ammonium salt and pillar[5]arene/alkyl chain)for supramolecular polymers.How do you get into this specific field?Could you please share some experiences with our readers?I got my introduction to supramolecular chemistry during the postgraduate period.There are many phenomena closely related to the weak non-covalent interactions in nature,such as the storage and transmission of genetic information through the DNA double helix structure.Inspired by these fascinating natural phenomena,scientists try to use non-covalent Interactions to prepare many very complex self-assembled systems including supramolecular polymers from natural and artificially designed structural units.In 1987,Lehn,Cram,and Pederson won the Nobel Prize for their contribution to supramolecular chemistry.At present,supramolecular chemistry has developed into an emerging discipline formed by the intersection of chemistry,physics,life sciences,materials science,and electronic engineering.
