title: Tribenzotriquinacene-Based Crown Ethers: Synthesis and Selective Complexation with Ammonium Salts.
abstract: Two tribenzotriquinacene-based crown ethers, TBTQ-dibenzo-24-crown-8 5 and TBTQ-benzo-21-crown-7 6, were prepared from the key TBTQ intermediate, 2,3-dihydroxy-4b,8b,12b,12d-tetramethyltribenzotriquinacene (13), which in turn was synthesized in six steps using two variants of our cyclodehydration method on a multigram scale. The host-guest complexation properties of the TBTQ-based crown ethers 5 and 6 with a paraquat derivative, 16, and two secondary ammonium salts, 17 and 18, were studied by1H NMR spectroscopy and mass spectrometry. It was found that host 5 binds to the paraquat derivative 16 as a 1:1 complex in CDCl3/CD3CN solution with an association constant of Ka= (9.2 ± 1.8) × 102M-1, whereas no complexation was found for 17 and 18. In contrast, the TBTQ-crown ether 6 assembles selectively with dibutylammonium hexafluorophosphate 18 as a 1:1 complex in CDCl3/CD3COCD3[Ka= (5.0 ± 1.4) × 102M-1], for which a threaded [2]pseudorotaxane structure is assumed.
authors.affiliation: State Key Laboratory of Applied Organic Chemistry & College of Chemistry and Chemical Engineering, Lanzhou University , Lanzhou 730000, P. R. China.
authors.forename: Yu-Fei
authors.initials: YF
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Applied Organic Chemistry & College of Chemistry and Chemical Engineering, Lanzhou University , Lanzhou 730000, P. R. China.
authors.forename: Xiao-Ping
authors.identifier: 0000-0001-8340-1122
authors.initials: XP
authors.lastname: Cao
authors.affiliation: Department of Chemistry, Center of Novel Functional Molecules and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong , Shatin, Hong Kong.
authors.forename: Hak-Fun
authors.initials: HF
authors.lastname: Chow
authors.affiliation: Department of Chemistry and Center for Molecular Materials (CM2), Bielefeld University , 33615 Bielefeld, Germany.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Kuck