title: Organogel formation by a cholesterol-stoppered bistable [2]rotaxane and its dumbbell precursor.
abstract: The switching properties, gelation behavior, and self-organization of a cholesterol-stoppered bistable [2]rotaxane containing a cyclobis(paraquat-p-phenylene) ring and tetrathiafulvalene/1,5-dioxynaphthalene recognition units situated in the rod portion of the dumbbell component have been investigated by electrochemical, spectroscopic, and microscopic means. The cyclobis(paraquat-p-phenylene) ring in the [2]rotaxane can be switched between the tetrathiafulvalene and 1,5-dioxynaphthalene recognition units by addressing the redox properties of the tetrathiafulvalene unit. The organogels can be prepared by dissolving the [2]rotaxane and its dumbbell precursor in a CH2Cl2/MeOH (3:2) mixed solvent and liquified by adding the oxidant Fe(ClO4)3. Direct evidence for the self-organization was obtained from AFM investigations which have shown that both of the [2]rotaxane and its dumbbell precursor form linear superstructures which we propose are helical in nature.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095, USA.
authors.forename: Yan-Li
authors.initials: YL
authors.lastname: Zhao
authors.forename: Ivan
authors.initials: I
authors.lastname: Aprahamian
authors.forename: Ali
authors.initials: A
authors.lastname: Trabolsi
authors.forename: Natalia
authors.initials: N
authors.lastname: Erina
authors.forename: J Fraser
authors.initials: JF
authors.lastname: Stoddart
mesh_terms: D002784:Cholesterol / Q000737:chemistry*; D002942:Circular Dichroism; D005782:Gels / Q000737:chemistry; D006571:Heterocyclic Compounds / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010269:Paraquat / Q000031:analogs & derivatives / Q000737:chemistry; D043862:Rotaxanes / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D005782:Gels; D006571:Heterocyclic Compounds; D043862:Rotaxanes; D002784:Cholesterol; C063887:tetrathiafulvalene; D010269:Paraquat