title: Nondegenerate pi-donor/pi-acceptor [2]catenanes containing proton-ionizable 1H-1,2,4-triazole subunits: synthesis and spontaneous resolution.
abstract: Chirality can hold the key to inducing directionality of motion in components of molecular devices. With this idea in mind, we describe here 1) the template-directed synthesis of two [2]catenanes wherein cyclobis(paraquat-p-phenylene) is interlocked with polyether macrocycles containing, in addition to one 3,5-bis(oxymethylene)-1H-1,2,4-triazole unit, either one 1,4-dioxybenzene or one 1,5-dioxynaphthalene ring system. We also report 2) the full characterization of both [2]catenanes by fast atom bombardment mass spectrometry (FABMS), X-ray crystallography, and dynamic (1)H NMR spectroscopy. We reveal 3) the fact that the [2]catenanes not only exist, both in the solution-state and in the solid-state, as strictly one of the two possible translational isomers, but that they also exhibit spontaneous resolution on crystallization leading to formation of homochiral crystals, as indicated by X-ray crystallography and circular dichroism (CD) experiments. Finally, we comment 4) on the chances of switching these catenanes chemically.
authors.affiliation: Laboratori de Química Orgànica, Facultat de Farmàcia and Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, Avda. Joan XXIII s/n, 08028-Barcelona, Spain.
authors.forename: Ermitas
authors.initials: E
authors.lastname: Alcalde
authors.forename: Lluïsa
authors.initials: L
authors.lastname: Pérez-García
authors.forename: Susana
authors.initials: S
authors.lastname: Ramos
authors.forename: J Fraser
authors.initials: JF
authors.lastname: Stoddart
authors.forename: Andrew J P
authors.initials: AJ
authors.lastname: White
authors.forename: David J
authors.initials: DJ
authors.lastname: Williams
mesh_terms: D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011522:Protons; D021241:Spectrometry, Mass, Electrospray Ionization; D016339:Spectrometry, Mass, Fast Atom Bombardment; D014230:Triazoles / Q000737:chemistry*
chemical_list: D011522:Protons; D014230:Triazoles