title: Synthesis and Molecular Recognition of Water-Soluble S6-Corona[3]arene[3]pyridazines.
abstract: We report the efficient and scalable synthesis and molecular-recognition properties of novel and water-soluble S6-corona[3]arene[3]pyridazines. The synthesis comprises a one-pot nucleophilic aromatic substitution reaction between diesters of 2,5-dimercaptoterephthalate and 3,6-dichlorotetrazine followed by the inverse electron-demand Diels-Alder reaction of the tetrazine moieties with an enamine and exhaustive saponification of esters. The resulting S6-corona[3]arene[3]pyridazines, which adopt a 1,3,5-alternate conformation in the crystalline state, are able to selectively form stable 1:1 complexes with dicationic guest species in water with association constants ranging from (1.10±0.06)×10(3)  M(-1) to (1.18±0.06)×10(5)  M(-1). The easy availability, large cavity size, strong and selective binding power render the water-soluble S6-corona[3]arene[3]pyridazines useful macrocyclic hosts in various disciplines of supramolecular chemistry.
authors.affiliation: Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084 (China).
authors.forename: Qing-Hui
authors.initials: QH
authors.lastname: Guo
authors.affiliation: Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084 (China).
authors.forename: Liang
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084 (China). wangmx@mail.tsinghua.edu.cn.
authors.forename: Mei-Xiang
authors.initials: MX
authors.lastname: Wang
mesh_terms: D047250:Calixarenes / Q000138:chemical synthesis* / Q000737:chemistry; D061565:Cycloaddition Reaction; D008958:Models, Molecular; D008968:Molecular Conformation; D011724:Pyridazines / Q000138:chemical synthesis* / Q000737:chemistry; D012995:Solubility; D014867:Water / Q000737:chemistry
chemical_list: D011724:Pyridazines; D014867:Water; D047250:Calixarenes
keywords: corona-arenes; host-guest systems; macrocycles; molecular recognition; paraquat